RE: Wanna Be a CCIE? Try This One [7:6076]
Would Moving one of the AREA 1 Routers into (a new area) Area2 Fix this?
-Original Message-
From: Michael L. Williams [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, May 30, 2001 6:54 PM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Good call I was going moreso by the diagram...
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Read carefully - routerA and routerB both have interfaces in Area0 and
Area1, which makes them both ABRs
-e-
- Original Message -
From: Michael L. Williams
To:
Sent: Wednesday, May 30, 2001 9:01 AM
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Wait a second.. where are the ABRs?How can a router that
communicates routes from one OSPF area to another not be an ABR? Am I
missing something?
Mike W.
Kevin Schwantz wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the case
in
my
network because I realise that routerA prefers Intra-Area routes and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has
been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area
(even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE
list?
The following message came through today. I thought the bright
folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on
Virtual
Links in OSPF. It was posted some time ago but I can't seem to
find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic
needs
to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual
link
has
to
use R1 (To create the V.Link). Does the traffic flow passed R1
(in
Area
1)
to Area 0 and then back to area 1, or does the actual flow just
to
R1
from
R2.
I cant remember the conclusion, and I cant seem to find it on
the
archives.
Quite interesting issues.
End of original question
Chuck
One IOS to forward them all.
One IOS to find them.
One IOS to summarize them all
And in the routing table bind them.
-JRR Chambers-
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to
[EMAIL PROTECTED]
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Report misconduct and Nondisclosure violations to
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FAQ, list archive
Re: Wanna Be a CCIE? Try This One [7:6076]
Giles,
I don't think its a OSPF Cost problem. I tried it without avail. I am not
very sure but I believe OSPF will prefer Intra-Area routes despite having an
alternate path that seemingly has a lower cost. Please correct me if I am
wrong. Could this be an administrative distance thing?
As much as I would have liked to come up with an ingenius solution, I was
not able to.
I have since changed Area 1 into Area 0. It works fine now but I have this
nagging feeling that something more constructive could have been done. The
solution I adopted seems more like a cheap work around. But I guess it works
and that matters more.
By the way, the network is much bigger than what I have illustrated. It
consist of around 40 routers spanning over 16 countries. Its a private IP
network that runs on MPLS to provide VPN's. My next project would be to
implement traffic engineering.
Kevin
Essame, Giles wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
The SPF tree involves determining a least-cost path from the router the
path
will be originating from. Therefore you need to adjust your costs
accordingly.
As per example, Area0 is a low cost due to I presume Area0 would be over a
high speed backbone.
routerArouterB
AREA0 55 AREA0
10 10
| |
10 10
routerC routerD
AREA1 20-20 AREA1
From Router A via router B to reach router D is cost of 15.
From Router A via router C to reach router D is cost of 30.
Router B is now the preferred route. If it a test network, try playing
around with the costs to do asymmetrical routing.
-Original Message-
From: Hire, Ejay [mailto:[EMAIL PROTECTED]]
Sent: Thursday, May 31, 2001 2:02 PM
To:
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Would Moving one of the AREA 1 Routers into (a new area) Area2 Fix this?
-Original Message-
From: Michael L. Williams [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, May 30, 2001 6:54 PM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Good call I was going moreso by the diagram...
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Read carefully - routerA and routerB both have interfaces in Area0 and
Area1, which makes them both ABRs
-e-
- Original Message -
From: Michael L. Williams
To:
Sent: Wednesday, May 30, 2001 9:01 AM
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Wait a second.. where are the ABRs?How can a router that
communicates routes from one OSPF area to another not be an ABR? Am I
missing something?
Mike W.
Kevin Schwantz wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the
case
in
my
network because I realise that routerA prefers Intra-Area routes
and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA
to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has
been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in
3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Ye
Re: Wanna Be a CCIE? Try This One [7:6076]
As you are likely aware, running TE over area borders isn't an available option these days due to the loss of traffic engineering info at those borders. Hence, migrating to a single area might enhance your ability to engineer traffic in your network. I would just keep an eye on the utilization of your routers particularity if they are running multiple routing tables as your mpls vpn comment suggests. *** REPLY SEPARATOR *** On 5/31/2001 at 11:02 AM Kevin Schwantz wrote: Giles, I don't think its a OSPF Cost problem. I tried it without avail. I am not very sure but I believe OSPF will prefer Intra-Area routes despite having an alternate path that seemingly has a lower cost. Please correct me if I am wrong. Could this be an administrative distance thing? As much as I would have liked to come up with an ingenius solution, I was not able to. I have since changed Area 1 into Area 0. It works fine now but I have this nagging feeling that something more constructive could have been done. The solution I adopted seems more like a cheap work around. But I guess it works and that matters more. By the way, the network is much bigger than what I have illustrated. It consist of around 40 routers spanning over 16 countries. Its a private IP network that runs on MPLS to provide VPN's. My next project would be to implement traffic engineering. Kevin Essame, Giles wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... The SPF tree involves determining a least-cost path from the router the path will be originating from. Therefore you need to adjust your costs accordingly. As per example, Area0 is a low cost due to I presume Area0 would be over a high speed backbone. routerArouterB AREA0 55 AREA0 10 10 | | 10 10 routerC routerD AREA1 20-20 AREA1 From Router A via router B to reach router D is cost of 15. From Router A via router C to reach router D is cost of 30. Router B is now the preferred route. If it a test network, try playing around with the costs to do asymmetrical routing. -Original Message- From: Hire, Ejay [mailto:[EMAIL PROTECTED]] Sent: Thursday, May 31, 2001 2:02 PM To: Subject: RE: Wanna Be a CCIE? Try This One [7:6076] Would Moving one of the AREA 1 Routers into (a new area) Area2 Fix this? -Original Message- From: Michael L. Williams [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 30, 2001 6:54 PM To: [EMAIL PROTECTED] Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Good call I was going moreso by the diagram... EA Louie wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Read carefully - routerA and routerB both have interfaces in Area0 and Area1, which makes them both ABRs -e- - Original Message - From: Michael L. Williams To: Sent: Wednesday, May 30, 2001 9:01 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Wait a second.. where are the ABRs?How can a router that communicates routes from one OSPF area to another not be an ABR? Am I missing something? Mike W. Kevin Schwantz wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... routerArouterB AREA0AREA0 || routerC routerD AREA1-AREA1 Since we are on the topic of OSPF, could someone help me out on the scenario above? Routers A and B have interfaces in Area 0 and Area1. I want traffic from routerA destined for routerD to go via router B. This is not the case in my network because I realise that routerA prefers Intra-Area routes and thus would route traffic to routerD via routerC. What tweaks must I make in order to force the traffic from routerA to routerD to go via routerB ? Someone suggested building a GRE tunnel between routerA and routerB and then configure the tunnel to be in AREA1. Any suggestions? Kevin W. Alan Robertson wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Guys, The actual traffic will not be routed up to area 0... Area 0 has been extended down to R2, so R2 is now a backbone router. R2 has interfaces in 3 areas now: Area1, Area2, and Area0 by means of it's virtual link. Any traffic originating in Area2 destined for Area1 will be routed directly by R2. This satisfies the Interarea traffic must traverse the backbone rule, because R2 *is* a backbone router. This is not theor
Re: Wanna Be a CCIE? Try This One [7:6076]
I am not very sure but I believe OSPF will prefer Intra-Area routes despite having an alternate path that seemingly has a lower cost. Please correct me if I am wrong. Could this be an administrative distance thing? Kevin, just for clarification, what you are describing has nothing to do with administrative distance. Administrative distance is about comparing the relative trustworthyness of routes learned via different routing protocols. Your dilema relates to the route selection criteria wholly within OSPF, and you're right... OSPF prefers Intra-area routes to Inter-area routes, regardless of cost. Cost is used when all else is equal in the previous steps of the route selection process, and the real bottom line is that cost becomes signifgant only when talking about routes within a single area. As much as I would have liked to come up with an ingenius solution, I was not able to. I have since changed Area 1 into Area 0. It works fine now but I have this nagging feeling that something more constructive could have been done. The solution I adopted seems more like a cheap work around. But I guess it works and that matters more. Don't feel too bad... You have acheived your goal. There's always going to be a sexier solution, and if you haven't noticed, put together in a room (or a mailing list), quality engineers will often disagree on matters of implementation. By the way, the network is much bigger than what I have illustrated. It consist of around 40 routers spanning over 16 countries. Its a private IP network that runs on MPLS to provide VPN's. My next project would be to implement traffic engineering. See, everybody... Bigger network than was initially described... BGP FOREVER!! ;) Alan (Doing the dance... Feeling the flow...) Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6621t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Wanna Be a CCIE? Try This One [7:6076]
Kevin, I didn't read the whole thread!, It would be more of a cost issue if your where inter-area routing (as you know). Glancing at your thread, that's what I mentally thought even though it states several times that the problem was over intra-area routing. - I must read more slowly! From what you say changing the area looks the only solution, though as I hate giving up on a solution how about this. If your destination networks on router D are Type 1 or Type 2 and summarisation is good you could implement static routing (weight 16) on router A in the routing table thus overriding OSPF weights value. If the static routes point to a loopback address on router B, then if router B fails the static routes would disappear from the routing table allowing the OSPF to take over thus providing a resilient route to router D via router C. The reason why I say on using a loopback is due to if router B fails or it's interface for area 0 fails router A will still retain the static routes in it routing table due to it's local interface for Area 0 will be up still up. It's not elegant, but if you desperately need to off load bandwidth / CPU utilisation via route C or you don't want to increase the size of Area 0 then this may be worth considering. Personally I prefer what you have done but I don't know your situation. I hope this helps! Regards Giles -Original Message- From: Peter Van Oene [mailto:[EMAIL PROTECTED]] Sent: Thursday, May 31, 2001 4:36 PM To: [EMAIL PROTECTED] Subject: Re: Wanna Be a CCIE? Try This One [7:6076] As you are likely aware, running TE over area borders isn't an available option these days due to the loss of traffic engineering info at those borders. Hence, migrating to a single area might enhance your ability to engineer traffic in your network. I would just keep an eye on the utilization of your routers particularity if they are running multiple routing tables as your mpls vpn comment suggests. *** REPLY SEPARATOR *** On 5/31/2001 at 11:02 AM Kevin Schwantz wrote: Giles, I don't think its a OSPF Cost problem. I tried it without avail. I am not very sure but I believe OSPF will prefer Intra-Area routes despite having an alternate path that seemingly has a lower cost. Please correct me if I am wrong. Could this be an administrative distance thing? As much as I would have liked to come up with an ingenius solution, I was not able to. I have since changed Area 1 into Area 0. It works fine now but I have this nagging feeling that something more constructive could have been done. The solution I adopted seems more like a cheap work around. But I guess it works and that matters more. By the way, the network is much bigger than what I have illustrated. It consist of around 40 routers spanning over 16 countries. Its a private IP network that runs on MPLS to provide VPN's. My next project would be to implement traffic engineering. Kevin Essame, Giles wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... The SPF tree involves determining a least-cost path from the router the path will be originating from. Therefore you need to adjust your costs accordingly. As per example, Area0 is a low cost due to I presume Area0 would be over a high speed backbone. routerArouterB AREA0 55 AREA0 10 10 | | 10 10 routerC routerD AREA1 20-20 AREA1 From Router A via router B to reach router D is cost of 15. From Router A via router C to reach router D is cost of 30. Router B is now the preferred route. If it a test network, try playing around with the costs to do asymmetrical routing. -Original Message- From: Hire, Ejay [mailto:[EMAIL PROTECTED]] Sent: Thursday, May 31, 2001 2:02 PM To: Subject: RE: Wanna Be a CCIE? Try This One [7:6076] Would Moving one of the AREA 1 Routers into (a new area) Area2 Fix this? -Original Message- From: Michael L. Williams [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 30, 2001 6:54 PM To: [EMAIL PROTECTED] Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Good call I was going moreso by the diagram... EA Louie wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Read carefully - routerA and routerB both have interfaces in Area0 and Area1, which makes them both ABRs -e- - Original Message - From: Michael L. Williams To: Sent: Wednesday, May 30, 2001 9:01 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Wait a second.. where are the ABRs?How can a router that communicates routes from one OSPF area to another not be an ABR? Am I missing something? Mike W. Kevin Schwantz wrote in message [EMAIL PROTECT
Re: Wanna Be a CCIE? Try This One [7:6076]
I forgot to mention putting it all into area 0... But that isnt the purpose of this message the purpose of this message is to tell everyone that i am putting this scenario together in my lab at home, and everyone is invited to come help. NOT EVERYONE WILL HAVE ENABLE. but feel free to log on, and remember that the boxes are only running plus, so max is five people logged in. my name is humboldt.ws / ofa.sh. the public login is groupstudy / groupstudy there is a 3640, a 4000, and a crapload of 2500s all capable of doing BGP =) (AND OSPF) - Original Message - From: Peter Van Oene To: Sent: Tuesday, May 29, 2001 3:03 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] As Alan correctly points out, path cost is irrelevant in this case as intra area routers will be preferred over inter. We tend to think that a small network could not be better served by applying the same principles that we might use for a larger environment. Why is that? Instead of letting the number of devices determine the right solution (Or more properly, a good solution), let's form a solution based on the specific requirements. A network with a small number of devices, but consisting of multiple sites, and redundant links, presents a unique challenge. Forget the number of devices, and look at both the physical topology, and the problem that needs solving. BGPs powerful policy routing tools make it a good fit for this environment, when viewed from a requirements perspective. I think BGP is completely unecessary in this case.YES, splitting it into two ASes ans using eBGP would work (well), but i really think that modifying the path cost would be the right solution. remember that i never said eBGP wouldnt work. the initial discussion was about using BGP to do this in a SINGLE AS. ...don't get all in a tizzy, i recognize that you have a good idea. I just don't like it =P /me ducks It's not the only solution, but it is a valid solution, and in my opinion, it's a good solution. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: W. Alan Robertson ; Sent: Tuesday, May 29, 2001 1:02 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Absolutely, but he has traffic going from one router to another, it's not ever exiting the system. ...why would you want to break up an AS that small into two seperate private ASes? besides... the OSPF routes are going to take precedence, not that the admin dist. cant be changed, but ospf is 120, and BGP int routes are 200 (right?) - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 12:42 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, With all due respect, he doesn't have an IGP problem... He has a routing problem, and would like the ability to influence the flow of traffic under certain circumstances to provide for better network performance. After hearing a better explanation of the real issue, path selection for an International site, the use of BGP might go a long way toward solving the issue. He could very simply address his issues by breaking his OSPF into two seperate routing domains, and utilizing BGP as a means of interconnecting them. He could manipulate the traffic through the use of something as simple as AS-path prepending, or the other mechanisms Chuck mentioned (local preference, weight, or meds). Routing protocols are but tools, a simple means to an end. Like all tools, each has it's strengths and weaknesses. Most important is that you select the right one for a given situation. In the absence of more information, the use of BGP sounds like a pretty good solution to the given problem. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: Sent: Tuesday, May 29, 2001 11:29 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] next time you recomend using bgp to fix an IGP problem, im going to.., well, uh, just dont do it again. FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6456t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
Wait a second.. where are the ABRs?How can a router that communicates routes from one OSPF area to another not be an ABR? Am I missing something? Mike W. Kevin Schwantz wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... routerArouterB AREA0AREA0 || routerC routerD AREA1-AREA1 Since we are on the topic of OSPF, could someone help me out on the scenario above? Routers A and B have interfaces in Area 0 and Area1. I want traffic from routerA destined for routerD to go via router B. This is not the case in my network because I realise that routerA prefers Intra-Area routes and thus would route traffic to routerD via routerC. What tweaks must I make in order to force the traffic from routerA to routerD to go via routerB ? Someone suggested building a GRE tunnel between routerA and routerB and then configure the tunnel to be in AREA1. Any suggestions? Kevin W. Alan Robertson wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Guys, The actual traffic will not be routed up to area 0... Area 0 has been extended down to R2, so R2 is now a backbone router. R2 has interfaces in 3 areas now: Area1, Area2, and Area0 by means of it's virtual link. Any traffic originating in Area2 destined for Area1 will be routed directly by R2. This satisfies the Interarea traffic must traverse the backbone rule, because R2 *is* a backbone router. This is not theory... It is fact. Alan - Original Message - From: Andrew Larkins To: Sent: Monday, May 28, 2001 10:13 AM Subject: RE: Wanna Be a CCIE? Try This One [7:6076] agreedto area 0 then on to the intended area -Original Message- From: Circusnuts [mailto:[EMAIL PROTECTED]] Sent: 28 May 2001 15:50 To: [EMAIL PROTECTED] Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Chuck- my answer is Yes. The traffic from the Virtual Linked psuedo-ABR passes back to Area 0, before it's sent onto the intended Area (even if it's directly connected). Phil - Original Message - From: Chuck Larrieu To: Sent: Sunday, May 27, 2001 8:59 PM Subject: Wanna Be a CCIE? Try This One [7:6076] Ever wonder what the CCIE candidates talk about on the CCIE list? The following message came through today. I thought the bright folks on this list might be curious, and might want to venture an answer. Begin original question: Guys, I wonder if there is anybody who remembers the discussion on Virtual Links in OSPF. It was posted some time ago but I can't seem to find it. The scenario was something like this: ___ ___ |Area 0 | |Area1||Area2| |R0|--| R1 |--| R2 | |__| |_||_| There is a virtual link from area 2 to Area 0 via Area1. Traffic needs to get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link has to use R1 (To create the V.Link). Does the traffic flow passed R1 (in Area 1) to Area 0 and then back to area 1, or does the actual flow just to R1 from R2. I cant remember the conclusion, and I cant seem to find it on the archives. Quite interesting issues. End of original question Chuck One IOS to forward them all. One IOS to find them. One IOS to summarize them all And in the routing table bind them. -JRR Chambers- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6465t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
OR you could switch the 1 and the 0 in your diagram and have a properly
designed network!
-peter slow, CCNBlah
- Original Message -
From: Michael L. Williams
To:
Sent: Tuesday, May 29, 2001 10:59 PM
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Hey Chuck.. I just thought of something. you only need 2
routers to have 3 OSPF Areas in your diagram you show a router
inside
each OSPF area, however, OSPF routers (at least in my understanding and
most
Cisco Press book diagrams) are either totally inside an area (all
interfaces
inside a single Area, although they may connect elsewhere using other
routing protocols, we're only considering OSPF) or sit on the edge of
multiple areas (ABRs). Having said that, I would think the problem now
becomes one like this: (please excuse my ASCII drawing skills =)
| Area 0 | | Area 1 | | Area 2 |
| R1 R2 |
| ___| || |___|
The Virtual Link is now between R2 and R1. In this new scenario, there
is
no issue about where the traffic destined for Area 1 goes (it goes to R1).
Can you further explain the scenario you speak of with 3 OSPF Areas with a
router in each Area?That sounds more like a BGP thing where a router
is
inside an AS but can connect to routers in other ASes (via eBGP) without
being part of the other AS.
Mike W.
Chuck Larrieu wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Ever wonder what the CCIE candidates talk about on the CCIE list?
The following message came through today. I thought the bright folks on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on Virtual
Links in OSPF. It was posted some time ago but I can't seem to find it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic needs
to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link has
to
use R1 (To create the V.Link). Does the traffic flow passed R1 (in Area
1)
to Area 0 and then back to area 1, or does the actual flow just to R1
from
R2.
I cant remember the conclusion, and I cant seem to find it on the
archives.
Quite interesting issues.
End of original question
Chuck
One IOS to forward them all.
One IOS to find them.
One IOS to summarize them all
And in the routing table bind them.
-JRR Chambers-
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7i=6480t=6076
--
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Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
Read carefully - routerA and routerB both have interfaces in Area0 and
Area1, which makes them both ABRs
-e-
- Original Message -
From: Michael L. Williams
To:
Sent: Wednesday, May 30, 2001 9:01 AM
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Wait a second.. where are the ABRs?How can a router that
communicates routes from one OSPF area to another not be an ABR? Am I
missing something?
Mike W.
Kevin Schwantz wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the case in
my
network because I realise that routerA prefers Intra-Area routes and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area (even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE list?
The following message came through today. I thought the bright
folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on
Virtual
Links in OSPF. It was posted some time ago but I can't seem to
find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic
needs
to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual
link
has
to
use R1 (To create the V.Link). Does the traffic flow passed R1 (in
Area
1)
to Area 0 and then back to area 1, or does the actual flow just to
R1
from
R2.
I cant remember the conclusion, and I cant seem to find it on the
archives.
Quite interesting issues.
End of original question
Chuck
One IOS to forward them all.
One IOS to find them.
One IOS to summarize them all
And in the routing table bind them.
-JRR Chambers-
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to
[EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to
[EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to
[EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
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Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
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Report misconduct a
Re: Wanna Be a CCIE? Try This One [7:6076]
Good call I was going moreso by the diagram...
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Read carefully - routerA and routerB both have interfaces in Area0 and
Area1, which makes them both ABRs
-e-
- Original Message -
From: Michael L. Williams
To:
Sent: Wednesday, May 30, 2001 9:01 AM
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Wait a second.. where are the ABRs?How can a router that
communicates routes from one OSPF area to another not be an ABR? Am I
missing something?
Mike W.
Kevin Schwantz wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the case
in
my
network because I realise that routerA prefers Intra-Area routes and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has
been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area
(even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE
list?
The following message came through today. I thought the bright
folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on
Virtual
Links in OSPF. It was posted some time ago but I can't seem to
find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic
needs
to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual
link
has
to
use R1 (To create the V.Link). Does the traffic flow passed R1
(in
Area
1)
to Area 0 and then back to area 1, or does the actual flow just
to
R1
from
R2.
I cant remember the conclusion, and I cant seem to find it on
the
archives.
Quite interesting issues.
End of original question
Chuck
One IOS to forward them all.
One IOS to find them.
One IOS to summarize them all
And in the routing table bind them.
-JRR Chambers-
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to
[EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to
[EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to
[EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclos
Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic from
routerA destined for routerD to go via router B. This is not the case in my
network because I realise that routerA prefers Intra-Area routes and thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3 areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area (even if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE list?
The following message came through today. I thought the bright folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on Virtual
Links in OSPF. It was posted some time ago but I can't seem to find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic needs
to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link
has
to
use R1 (To create the V.Link). Does the traffic flow passed R1 (in
Area
1)
to Area 0 and then back to area 1, or does the actual flow just to R1
from
R2.
I cant remember the conclusion, and I cant seem to find it on the
archives.
Quite interesting issues.
End of original question
Chuck
One IOS to forward them all.
One IOS to find them.
One IOS to summarize them all
And in the routing table bind them.
-JRR Chambers-
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
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Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7i=6215t=6076
--
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Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Wanna Be a CCIE? Try This One [7:6076]
Place a summary route to null 0 for the networks on Router D on your OSPF
routers and set the metrics appropriately for the summary route
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 10:03 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic from
routerA destined for routerD to go via router B. This is not the case in my
network because I realise that routerA prefers Intra-Area routes and thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3 areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area (even if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE list?
The following message came through today. I thought the bright folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on Virtual
Links in OSPF. It was posted some time ago but I can't seem to find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic needs
to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link
has
to
use R1 (To create the V.Link). Does the traffic flow passed R1 (in
Area
1)
to Area 0 and then back to area 1, or does the actual flow just to R1
from
R2.
I cant remember the conclusion, and I cant seem to find it on the
archives.
Quite interesting issues.
End of original question
Chuck
One IOS to forward them all.
One IOS to find them.
One IOS to summarize them all
And in the routing table bind them.
-JRR Chambers-
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
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Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
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Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7i=6217t=6076
--
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Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Wanna Be a CCIE? Try This One [7:6076]
Run BGP on all routers and manipulate the path with local preference or
weights or meds?
Static routes?
Change to EIGRP?
Disconnect the link from A to C?
Put router B into area 1?
Sure - a tunnel will work also
Sorry, I've been reading too many things this weekend.
Chuck
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 7:03 AM
To: [EMAIL PROTECTED]
Subject:Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic from
routerA destined for routerD to go via router B. This is not the case in my
network because I realise that routerA prefers Intra-Area routes and thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3 areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject:Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area (even if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject:Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE list?
The following message came through today. I thought the bright folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on Virtual
Links in OSPF. It was posted some time ago but I can't seem to find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic needs
to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link
has
to
use R1 (To create the V.Link). Does the traffic flow passed R1 (in
Area
1)
to Area 0 and then back to area 1, or does the actual flow just to R1
from
R2.
I cant remember the conclusion, and I cant seem to find it on the
archives.
Quite interesting issues.
End of original question
Chuck
One IOS to forward them all.
One IOS to find them.
One IOS to summarize them all
And in the routing table bind them.
-JRR Chambers-
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
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Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
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Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7i=6225t=6076
--
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Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
well, since C and D are in the same area they have the tame topology DB. they KNOW the best route to each other and are going to use it. the tunnel idea is kinda stupid. first let me ask why you would want traffic between two directly connected routers to NOT use that link? ...But anyway, i would suggest policy routing in this case, or if there is a large traffic volume (too much for routers C and D to process switch, make static routes. other options include putting C and D in their own areas, and making each a stub, and get rid of that link between C and D. that would be the best idea... play with plath costs, and you might try a virtual link as well between C and D, but break glass only in case of emergency, if you know what i mean =P -Peter - Original Message - From: Kevin Schwantz To: Sent: Tuesday, May 29, 2001 10:03 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] routerArouterB AREA0AREA0 || routerC routerD AREA1-AREA1 Since we are on the topic of OSPF, could someone help me out on the scenario above? Routers A and B have interfaces in Area 0 and Area1. I want traffic from routerA destined for routerD to go via router B. This is not the case in my network because I realise that routerA prefers Intra-Area routes and thus would route traffic to routerD via routerC. What tweaks must I make in order to force the traffic from routerA to routerD to go via routerB ? Someone suggested building a GRE tunnel between routerA and routerB and then configure the tunnel to be in AREA1. Any suggestions? Kevin W. Alan Robertson wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Guys, The actual traffic will not be routed up to area 0... Area 0 has been extended down to R2, so R2 is now a backbone router. R2 has interfaces in 3 areas now: Area1, Area2, and Area0 by means of it's virtual link. Any traffic originating in Area2 destined for Area1 will be routed directly by R2. This satisfies the Interarea traffic must traverse the backbone rule, because R2 *is* a backbone router. This is not theory... It is fact. Alan - Original Message - From: Andrew Larkins To: Sent: Monday, May 28, 2001 10:13 AM Subject: RE: Wanna Be a CCIE? Try This One [7:6076] agreedto area 0 then on to the intended area -Original Message- From: Circusnuts [mailto:[EMAIL PROTECTED]] Sent: 28 May 2001 15:50 To: [EMAIL PROTECTED] Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Chuck- my answer is Yes. The traffic from the Virtual Linked psuedo-ABR passes back to Area 0, before it's sent onto the intended Area (even if it's directly connected). Phil - Original Message - From: Chuck Larrieu To: Sent: Sunday, May 27, 2001 8:59 PM Subject: Wanna Be a CCIE? Try This One [7:6076] Ever wonder what the CCIE candidates talk about on the CCIE list? The following message came through today. I thought the bright folks on this list might be curious, and might want to venture an answer. Begin original question: Guys, I wonder if there is anybody who remembers the discussion on Virtual Links in OSPF. It was posted some time ago but I can't seem to find it. The scenario was something like this: ___ ___ |Area 0 | |Area1||Area2| |R0|--| R1 |--| R2 | |__| |_||_| There is a virtual link from area 2 to Area 0 via Area1. Traffic needs to get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link has to use R1 (To create the V.Link). Does the traffic flow passed R1 (in Area 1) to Area 0 and then back to area 1, or does the actual flow just to R1 from R2. I cant remember the conclusion, and I cant seem to find it on the archives. Quite interesting issues. End of original question Chuck One IOS to forward them all. One IOS to find them. One IOS to summarize them all And in the routing table bind them. -JRR Chambers- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subs
Re: Wanna Be a CCIE? Try This One [7:6076]
... or route-map the router D network(s) to go through Router B at Router A - Original Message - From: Chris Larson To: Sent: Tuesday, May 29, 2001 7:24 AM Subject: RE: Wanna Be a CCIE? Try This One [7:6076] Place a summary route to null 0 for the networks on Router D on your OSPF routers and set the metrics appropriately for the summary route -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Kevin Schwantz Sent: Tuesday, May 29, 2001 10:03 AM To: [EMAIL PROTECTED] Subject: Re: Wanna Be a CCIE? Try This One [7:6076] routerArouterB AREA0AREA0 || routerC routerD AREA1-AREA1 Since we are on the topic of OSPF, could someone help me out on the scenario above? Routers A and B have interfaces in Area 0 and Area1. I want traffic from routerA destined for routerD to go via router B. This is not the case in my network because I realise that routerA prefers Intra-Area routes and thus would route traffic to routerD via routerC. What tweaks must I make in order to force the traffic from routerA to routerD to go via routerB ? Someone suggested building a GRE tunnel between routerA and routerB and then configure the tunnel to be in AREA1. Any suggestions? Kevin W. Alan Robertson wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Guys, The actual traffic will not be routed up to area 0... Area 0 has been extended down to R2, so R2 is now a backbone router. R2 has interfaces in 3 areas now: Area1, Area2, and Area0 by means of it's virtual link. Any traffic originating in Area2 destined for Area1 will be routed directly by R2. This satisfies the Interarea traffic must traverse the backbone rule, because R2 *is* a backbone router. This is not theory... It is fact. Alan - Original Message - From: Andrew Larkins To: Sent: Monday, May 28, 2001 10:13 AM Subject: RE: Wanna Be a CCIE? Try This One [7:6076] agreedto area 0 then on to the intended area -Original Message- From: Circusnuts [mailto:[EMAIL PROTECTED]] Sent: 28 May 2001 15:50 To: [EMAIL PROTECTED] Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Chuck- my answer is Yes. The traffic from the Virtual Linked psuedo-ABR passes back to Area 0, before it's sent onto the intended Area (even if it's directly connected). Phil - Original Message - From: Chuck Larrieu To: Sent: Sunday, May 27, 2001 8:59 PM Subject: Wanna Be a CCIE? Try This One [7:6076] Ever wonder what the CCIE candidates talk about on the CCIE list? The following message came through today. I thought the bright folks on this list might be curious, and might want to venture an answer. Begin original question: Guys, I wonder if there is anybody who remembers the discussion on Virtual Links in OSPF. It was posted some time ago but I can't seem to find it. The scenario was something like this: ___ ___ |Area 0 | |Area1||Area2| |R0|--| R1 |--| R2 | |__| |_||_| There is a virtual link from area 2 to Area 0 via Area1. Traffic needs to get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link has to use R1 (To create the V.Link). Does the traffic flow passed R1 (in Area 1) to Area 0 and then back to area 1, or does the actual flow just to R1 from R2. I cant remember the conclusion, and I cant seem to find it on the archives. Quite interesting issues. End of original question Chuck One IOS to forward them all. One IOS to find them. One IOS to summarize them all And in the routing table bind them. -JRR Chambers- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted
Re: Wanna Be a CCIE? Try This One [7:6076]
next time you recomend using bgp to fix an IGP problem, im going to.., well, uh, just dont do it again. - Original Message - From: Chuck Larrieu To: Sent: Tuesday, May 29, 2001 10:38 AM Subject: RE: Wanna Be a CCIE? Try This One [7:6076] Run BGP on all routers and manipulate the path with local preference or weights or meds? Static routes? Change to EIGRP? Disconnect the link from A to C? Put router B into area 1? Sure - a tunnel will work also Sorry, I've been reading too many things this weekend. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Kevin Schwantz Sent: Tuesday, May 29, 2001 7:03 AM To: [EMAIL PROTECTED] Subject: Re: Wanna Be a CCIE? Try This One [7:6076] routerArouterB AREA0AREA0 || routerC routerD AREA1-AREA1 Since we are on the topic of OSPF, could someone help me out on the scenario above? Routers A and B have interfaces in Area 0 and Area1. I want traffic from routerA destined for routerD to go via router B. This is not the case in my network because I realise that routerA prefers Intra-Area routes and thus would route traffic to routerD via routerC. What tweaks must I make in order to force the traffic from routerA to routerD to go via routerB ? Someone suggested building a GRE tunnel between routerA and routerB and then configure the tunnel to be in AREA1. Any suggestions? Kevin W. Alan Robertson wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Guys, The actual traffic will not be routed up to area 0... Area 0 has been extended down to R2, so R2 is now a backbone router. R2 has interfaces in 3 areas now: Area1, Area2, and Area0 by means of it's virtual link. Any traffic originating in Area2 destined for Area1 will be routed directly by R2. This satisfies the Interarea traffic must traverse the backbone rule, because R2 *is* a backbone router. This is not theory... It is fact. Alan - Original Message - From: Andrew Larkins To: Sent: Monday, May 28, 2001 10:13 AM Subject: RE: Wanna Be a CCIE? Try This One [7:6076] agreedto area 0 then on to the intended area -Original Message- From: Circusnuts [mailto:[EMAIL PROTECTED]] Sent: 28 May 2001 15:50 To: [EMAIL PROTECTED] Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Chuck- my answer is Yes. The traffic from the Virtual Linked psuedo-ABR passes back to Area 0, before it's sent onto the intended Area (even if it's directly connected). Phil - Original Message - From: Chuck Larrieu To: Sent: Sunday, May 27, 2001 8:59 PM Subject: Wanna Be a CCIE? Try This One [7:6076] Ever wonder what the CCIE candidates talk about on the CCIE list? The following message came through today. I thought the bright folks on this list might be curious, and might want to venture an answer. Begin original question: Guys, I wonder if there is anybody who remembers the discussion on Virtual Links in OSPF. It was posted some time ago but I can't seem to find it. The scenario was something like this: ___ ___ |Area 0 | |Area1||Area2| |R0|--| R1 |--| R2 | |__| |_||_| There is a virtual link from area 2 to Area 0 via Area1. Traffic needs to get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link has to use R1 (To create the V.Link). Does the traffic flow passed R1 (in Area 1) to Area 0 and then back to area 1, or does the actual flow just to R1 from R2. I cant remember the conclusion, and I cant seem to find it on the archives. Quite interesting issues. End of original question Chuck One IOS to forward them all. One IOS to find them. One IOS to summarize them all And in the routing table bind them. -JRR Chambers- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groups
Re: Wanna Be a CCIE? Try This One [7:6076]
Thanks for the recommendations. Firstly, let me explain why I need the
routing to behave in such a way. The reasons are purely geographical and I
want to reduce latency. Routers A and B are in London and connected back to
back via FastEth. Routers C and D are in and SanJose and NewYork
respectively(Connected to both London routers via FR).
I certaintly won't want traffic originating from RouterA ( London ) destined
for RouterD (NewYork) to have to go to SanJose first. It would be much
better if the hop is A-B-D instead of A-C-D.
Schwantz
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
... or route-map the router D network(s) to go through Router B at Router
A
- Original Message -
From: Chris Larson
To:
Sent: Tuesday, May 29, 2001 7:24 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Place a summary route to null 0 for the networks on Router D on your
OSPF
routers and set the metrics appropriately for the summary route
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 10:03 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the case in
my
network because I realise that routerA prefers Intra-Area routes and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area (even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE list?
The following message came through today. I thought the bright
folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on
Virtual
Links in OSPF. It was posted some time ago but I can't seem to
find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic
needs
to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual
link
has
to
use R1 (To create the V.Link). Does the traffic flow passed R1 (in
Area
1)
to Area 0 and then back to area 1, or does the actual flow just to
R1
from
R2.
I cant remember the conclusion, and I cant seem to find it on the
archives.
Quite interesting issues.
End of original question
Chuck
One IOS to forward them all.
One IOS to find them.
One IOS to summarize them all
And in the routing table bind them.
-JRR Chambers-
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to
[EMAIL PROTECTED]
FAQ, list archives, and subscriptio
Re: Wanna Be a CCIE? Try This One [7:6076]
Peter,
Thanks for your input. I hope my description of the geographical topology in
another post should point out why I want my traffic to route in the manner I
have described. Taking down the link between C and D is not an option. You
mentioned Virtual links. I always thought they were used to link an area to
area 0. I don't see how it can be applied to my case. I can take the easy
way out and place all the routers in area 0 but want to use that action as
my last resort.
kevin
Peter I. Slow, CCNP Voice Specialist wrote in
message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
well, since C and D are in the same area they have the tame topology DB.
they KNOW the best route to each other and are going to use it.
the tunnel idea is kinda stupid.
first let me ask why you would want traffic between two directly connected
routers to NOT use that link?
...But anyway, i would suggest policy routing in this case, or if there is
a
large traffic volume (too much for routers C and D to process switch,
make
static routes.
other options include putting C and D in their own areas, and making each
a
stub, and get rid of that link between C and D. that would be the best
idea...
play with plath costs,
and you might try a virtual link as well between C and D,
but break glass only in case of emergency, if you know what i mean =P
-Peter
- Original Message -
From: Kevin Schwantz
To:
Sent: Tuesday, May 29, 2001 10:03 AM
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the case in
my
network because I realise that routerA prefers Intra-Area routes and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area (even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE list?
The following message came through today. I thought the bright
folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on
Virtual
Links in OSPF. It was posted some time ago but I can't seem to
find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic
needs
to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual
link
has
to
use R1 (To create the V.Link). Does the traffic flow passed R1 (in
Area
1)
to Area 0 and then back to area 1, or does the actual flow just to
R1
from
R2.
I cant remember the conclusion, and I cant seem to find it on the
archives.
Quite interesting issues.
End of original question
Chuck
One IOS to forward them all.
One IOS to find them.
One IOS to su
Re: Wanna Be a CCIE? Try This One [7:6076]
Have you tried an inboud distribution list on Router A's area 1
interfaces. If router A doesn't learn the Router D routes thru those
interfaces it should then use Area 0.
Worth a try.
DaveC
Kevin Schwantz wrote:
Thanks for the recommendations. Firstly, let me explain why I need the
routing to behave in such a way. The reasons are purely geographical and I
want to reduce latency. Routers A and B are in London and connected back to
back via FastEth. Routers C and D are in and SanJose and NewYork
respectively(Connected to both London routers via FR).
I certaintly won't want traffic originating from RouterA ( London )
destined
for RouterD (NewYork) to have to go to SanJose first. It would be much
better if the hop is A-B-D instead of A-C-D.
Schwantz
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
... or route-map the router D network(s) to go through Router B at Router
A
- Original Message -
From: Chris Larson
To:
Sent: Tuesday, May 29, 2001 7:24 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Place a summary route to null 0 for the networks on Router D on your
OSPF
routers and set the metrics appropriately for the summary route
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 10:03 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the case
in
my
network because I realise that routerA prefers Intra-Area routes and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has
been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area
(even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE list?
The following message came through today. I thought the bright
folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on
Virtual
Links in OSPF. It was posted some time ago but I can't seem to
find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic
needs
to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual
link
has
to
use R1 (To create the V.Link). Does the traffic flow passed R1
(in
Area
1)
to Area 0 and then back to area 1, or does the actual flow just
to
R1
from
R2.
I cant remember the conclusion, and I cant seem to find it on the
archives.
Quite interesting issues.
End of original question
Chuck
Re: Wanna Be a CCIE? Try This One [7:6076]
Wouldn't you still like the route to D to be available through C if the link
between B and D goes down, or if router B goes down? A distribution list
would stop that.
--
James Haynes
Network Architect
Cendant IT
A+,MCSE,CCNA,CCDA,CCNP,CCDP
David Chandler wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Have you tried an inboud distribution list on Router A's area 1
interfaces. If router A doesn't learn the Router D routes thru those
interfaces it should then use Area 0.
Worth a try.
DaveC
Kevin Schwantz wrote:
Thanks for the recommendations. Firstly, let me explain why I need the
routing to behave in such a way. The reasons are purely geographical and
I
want to reduce latency. Routers A and B are in London and connected back
to
back via FastEth. Routers C and D are in and SanJose and NewYork
respectively(Connected to both London routers via FR).
I certaintly won't want traffic originating from RouterA ( London )
destined
for RouterD (NewYork) to have to go to SanJose first. It would be much
better if the hop is A-B-D instead of A-C-D.
Schwantz
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
... or route-map the router D network(s) to go through Router B at
Router
A
- Original Message -
From: Chris Larson
To:
Sent: Tuesday, May 29, 2001 7:24 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Place a summary route to null 0 for the networks on Router D on your
OSPF
routers and set the metrics appropriately for the summary route
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf
Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 10:03 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the
case
in
my
network because I realise that routerA prefers Intra-Area routes
and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA
to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has
been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in
3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area
(even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE
list?
The following message came through today. I thought the bright
folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on
Virtual
Links in OSPF. It was posted some time ago but I can't seem to
find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via
Re: Wanna Be a CCIE? Try This One [7:6076]
Thats a good point James. Distribution lists are too restrictive and not
very scalable in this situation. I think my first course of action would be
to tweak the OSPF cost between A and C so that traffic from A to D will go
via B instead of C. My only concern is that I might create the situation
where traffic from A destined for C goes via B !! This would just be
creating a new problem.
Kevin
James Haynes wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Wouldn't you still like the route to D to be available through C if the
link
between B and D goes down, or if router B goes down? A distribution list
would stop that.
--
James Haynes
Network Architect
Cendant IT
A+,MCSE,CCNA,CCDA,CCNP,CCDP
David Chandler wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Have you tried an inboud distribution list on Router A's area 1
interfaces. If router A doesn't learn the Router D routes thru those
interfaces it should then use Area 0.
Worth a try.
DaveC
Kevin Schwantz wrote:
Thanks for the recommendations. Firstly, let me explain why I need the
routing to behave in such a way. The reasons are purely geographical
and
I
want to reduce latency. Routers A and B are in London and connected
back
to
back via FastEth. Routers C and D are in and SanJose and NewYork
respectively(Connected to both London routers via FR).
I certaintly won't want traffic originating from RouterA ( London )
destined
for RouterD (NewYork) to have to go to SanJose first. It would be much
better if the hop is A-B-D instead of A-C-D.
Schwantz
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
... or route-map the router D network(s) to go through Router B at
Router
A
- Original Message -
From: Chris Larson
To:
Sent: Tuesday, May 29, 2001 7:24 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Place a summary route to null 0 for the networks on Router D on
your
OSPF
routers and set the metrics appropriately for the summary route
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On
Behalf
Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 10:03 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on
the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want
traffic
from
routerA destined for routerD to go via router B. This is not the
case
in
my
network because I realise that routerA prefers Intra-Area routes
and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA
to
routerD to go via routerB ? Someone suggested building a GRE
tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0
has
been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces
in
3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be
routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area
(even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE
list?
The following messa
RE: Wanna Be a CCIE? Try This One [7:6076]
Okay, based on all of the information, we can come up with a solution.
Scenario:
4 routers connected in a ring by various speed links
Objectives:
Router A's traffic for Router C should be sent directly to C
Router B's traffic for Router D should be sent directly to D
Router A's Traffic for B or D should be sent to RouterB
Router B's Traffic for C or A should be sent to RouterB
OSPF should be configured in such a way as to allow the network to maintain
reachability in the event of any single link failure.
Do as little configuration as possible
Scenario Solution:
See Drawing 1
http://www.miscenterprises.com/schwantz.gif
Meets all of the requirements except for the Do as little work as possible
because you have to manually configure the cost of every link...
Anyway, you give the FastEthernet Link a low cost, and give the San
Jose-NewYork link a high cost, but not so high that it causes traffic from D
to C to go D-B-A-C.
If I missed any of the objectives, let me know and I'll wiggle the numbers
around to make it work.
-Ejay
-Original Message-
From: Kevin Schwantz [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, May 29, 2001 11:38 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Thanks for the recommendations. Firstly, let me explain why I need the
routing to behave in such a way. The reasons are purely geographical and I
want to reduce latency. Routers A and B are in London and connected back to
back via FastEth. Routers C and D are in and SanJose and NewYork
respectively(Connected to both London routers via FR).
I certaintly won't want traffic originating from RouterA ( London ) destined
for RouterD (NewYork) to have to go to SanJose first. It would be much
better if the hop is A-B-D instead of A-C-D.
Schwantz
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
... or route-map the router D network(s) to go through Router B at Router
A
- Original Message -
From: Chris Larson
To:
Sent: Tuesday, May 29, 2001 7:24 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Place a summary route to null 0 for the networks on Router D on your
OSPF
routers and set the metrics appropriately for the summary route
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 10:03 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the case in
my
network because I realise that routerA prefers Intra-Area routes and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area (even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE list?
The following message came through today. I thought the bright
folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if ther
Re: Wanna Be a CCIE? Try This One [7:6076]
Peter, With all due respect, he doesn't have an IGP problem... He has a routing problem, and would like the ability to influence the flow of traffic under certain circumstances to provide for better network performance. After hearing a better explanation of the real issue, path selection for an International site, the use of BGP might go a long way toward solving the issue. He could very simply address his issues by breaking his OSPF into two seperate routing domains, and utilizing BGP as a means of interconnecting them. He could manipulate the traffic through the use of something as simple as AS-path prepending, or the other mechanisms Chuck mentioned (local preference, weight, or meds). Routing protocols are but tools, a simple means to an end. Like all tools, each has it's strengths and weaknesses. Most important is that you select the right one for a given situation. In the absence of more information, the use of BGP sounds like a pretty good solution to the given problem. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: Sent: Tuesday, May 29, 2001 11:29 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] next time you recomend using bgp to fix an IGP problem, im going to.., well, uh, just dont do it again. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6250t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
Absolutely, but he has traffic going from one router to another, it's not ever exiting the system. ...why would you want to break up an AS that small into two seperate private ASes? besides... the OSPF routes are going to take precedence, not that the admin dist. cant be changed, but ospf is 120, and BGP int routes are 200 (right?) - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 12:42 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, With all due respect, he doesn't have an IGP problem... He has a routing problem, and would like the ability to influence the flow of traffic under certain circumstances to provide for better network performance. After hearing a better explanation of the real issue, path selection for an International site, the use of BGP might go a long way toward solving the issue. He could very simply address his issues by breaking his OSPF into two seperate routing domains, and utilizing BGP as a means of interconnecting them. He could manipulate the traffic through the use of something as simple as AS-path prepending, or the other mechanisms Chuck mentioned (local preference, weight, or meds). Routing protocols are but tools, a simple means to an end. Like all tools, each has it's strengths and weaknesses. Most important is that you select the right one for a given situation. In the absence of more information, the use of BGP sounds like a pretty good solution to the given problem. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: Sent: Tuesday, May 29, 2001 11:29 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] next time you recomend using bgp to fix an IGP problem, im going to.., well, uh, just dont do it again. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6252t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
Or use a route-map to increase the path cost...
Otherwise you lose that filtered path as a backup route...
Peter Slow, CCNP Voice Specialist
Network Engineer
Planetary Networks
535 West 34th Street
New York, NY
10001
Cell:(516) 782.1535
Desk: (646) 792.2395
Mail: [EMAIL PROTECTED]
Fax:(646) 792.2396
- Original Message -
From: David Chandler
To:
Sent: Tuesday, May 29, 2001 12:00 PM
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Have you tried an inboud distribution list on Router A's area 1
interfaces. If router A doesn't learn the Router D routes thru those
interfaces it should then use Area 0.
Worth a try.
DaveC
Kevin Schwantz wrote:
Thanks for the recommendations. Firstly, let me explain why I need the
routing to behave in such a way. The reasons are purely geographical and
I
want to reduce latency. Routers A and B are in London and connected back
to
back via FastEth. Routers C and D are in and SanJose and NewYork
respectively(Connected to both London routers via FR).
I certaintly won't want traffic originating from RouterA ( London )
destined
for RouterD (NewYork) to have to go to SanJose first. It would be much
better if the hop is A-B-D instead of A-C-D.
Schwantz
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
... or route-map the router D network(s) to go through Router B at
Router
A
- Original Message -
From: Chris Larson
To:
Sent: Tuesday, May 29, 2001 7:24 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Place a summary route to null 0 for the networks on Router D on your
OSPF
routers and set the metrics appropriately for the summary route
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf
Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 10:03 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the
case
in
my
network because I realise that routerA prefers Intra-Area routes
and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA
to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has
been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in
3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area
(even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE
list?
The following message came through today. I thought the bright
folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on
Virtual
Links in OSPF. It was posted some time ago but I can't seem to
find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--
Re: Wanna Be a CCIE? Try This One [7:6076]
Hey he could use MPLS to do traffic engineering, actually. What kind of routers are these? =P Peter Slow, CCNP Voice Specialist Network Engineer Planetary Networks 535 West 34th Street New York, NY 10001 Cell:(516) 782.1535 Desk: (646) 792.2395 Mail: [EMAIL PROTECTED] Fax:(646) 792.2396 - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 12:42 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, With all due respect, he doesn't have an IGP problem... He has a routing problem, and would like the ability to influence the flow of traffic under certain circumstances to provide for better network performance. After hearing a better explanation of the real issue, path selection for an International site, the use of BGP might go a long way toward solving the issue. He could very simply address his issues by breaking his OSPF into two seperate routing domains, and utilizing BGP as a means of interconnecting them. He could manipulate the traffic through the use of something as simple as AS-path prepending, or the other mechanisms Chuck mentioned (local preference, weight, or meds). Routing protocols are but tools, a simple means to an end. Like all tools, each has it's strengths and weaknesses. Most important is that you select the right one for a given situation. In the absence of more information, the use of BGP sounds like a pretty good solution to the given problem. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: Sent: Tuesday, May 29, 2001 11:29 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] next time you recomend using bgp to fix an IGP problem, im going to.., well, uh, just dont do it again. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6255t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
Im thinking that route maps which increase the path cost might be your best
bet.
Peter Slow, CCNP Voice Specialist
Network Engineer
Planetary Networks
535 West 34th Street
New York, NY
10001
Cell:(516) 782.1535
Desk: (646) 792.2395
Mail: [EMAIL PROTECTED]
Fax:(646) 792.2396
- Original Message -
From: Kevin Schwantz
To:
Sent: Tuesday, May 29, 2001 11:50 AM
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Peter,
Thanks for your input. I hope my description of the geographical topology
in
another post should point out why I want my traffic to route in the manner
I
have described. Taking down the link between C and D is not an option. You
mentioned Virtual links. I always thought they were used to link an area
to
area 0. I don't see how it can be applied to my case. I can take the easy
way out and place all the routers in area 0 but want to use that action as
my last resort.
kevin
Peter I. Slow, CCNP Voice Specialist wrote in
message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
well, since C and D are in the same area they have the tame topology DB.
they KNOW the best route to each other and are going to use it.
the tunnel idea is kinda stupid.
first let me ask why you would want traffic between two directly
connected
routers to NOT use that link?
...But anyway, i would suggest policy routing in this case, or if there
is
a
large traffic volume (too much for routers C and D to process switch,
make
static routes.
other options include putting C and D in their own areas, and making
each
a
stub, and get rid of that link between C and D. that would be the best
idea...
play with plath costs,
and you might try a virtual link as well between C and D,
but break glass only in case of emergency, if you know what i mean =P
-Peter
- Original Message -
From: Kevin Schwantz
To:
Sent: Tuesday, May 29, 2001 10:03 AM
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the case
in
my
network because I realise that routerA prefers Intra-Area routes and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has
been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area
(even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE
list?
The following message came through today. I thought the bright
folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on
Virtual
Links in OSPF. It was posted some time ago but I can't seem to
find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area
Re: Wanna Be a CCIE? Try This One [7:6076]
WOOPS. Due to me being a jackass. I have been looking at your diagram
incorrectly.
I would think that if OSPF is configured properly, this will already be the
case.
Can i see your routing tables, please?
preferably from all four routers.
Peter Slow, CCNP Voice Specialist
Network Engineer
Planetary Networks
535 West 34th Street
New York, NY
10001
Cell:(516) 782.1535
Desk: (646) 792.2395
Mail: [EMAIL PROTECTED]
Fax:(646) 792.2396
- Original Message -
From: Kevin Schwantz
To:
Sent: Tuesday, May 29, 2001 11:38 AM
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Thanks for the recommendations. Firstly, let me explain why I need the
routing to behave in such a way. The reasons are purely geographical and I
want to reduce latency. Routers A and B are in London and connected back
to
back via FastEth. Routers C and D are in and SanJose and NewYork
respectively(Connected to both London routers via FR).
I certaintly won't want traffic originating from RouterA ( London )
destined
for RouterD (NewYork) to have to go to SanJose first. It would be much
better if the hop is A-B-D instead of A-C-D.
Schwantz
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
... or route-map the router D network(s) to go through Router B at
Router
A
- Original Message -
From: Chris Larson
To:
Sent: Tuesday, May 29, 2001 7:24 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Place a summary route to null 0 for the networks on Router D on your
OSPF
routers and set the metrics appropriately for the summary route
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 10:03 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the case
in
my
network because I realise that routerA prefers Intra-Area routes and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has
been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area
(even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE
list?
The following message came through today. I thought the bright
folks
on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on
Virtual
Links in OSPF. It was posted some time ago but I can't seem to
find
it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic
needs
to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual
link
has
to
u
Re: Wanna Be a CCIE? Try This One [7:6076]
Peter, OSPF has a distance of 110, and yes, iBGP has a distance of 200. By having seperate routing domains for North America and Europe, he could use eBGP (Distance - 20) between his two networks. Distance wouldn't really do anything in this case, though, because European routes would not be learned via OSPF (Remember, we have theoretically split OSPF into two seperate routing domains, never the two shall meet). Instead, eBGP would be bridging the gap between the two OSPF networks. This would afford the opportunity to really take control of what routes were advertised between the two, and excercise strict control of the routing metrics, manipulating them in such a way as to ensure that the best path across the pond were utilized under all normal circumstances, but providing the redundant less preferred path in the event of some kind of outage. Can the same be accomplished via OSPF? Yes, but because we're dealing with Intra-area, and Inter-area routes, it may be more complex than by simply manipulating the link costs. Remember that OSPF chooses an Intra-area route with a Cost of 4,000,000 over an Inter-area route with a cost of 100. That's just one of the quirks of the protocol. As for Why would you want to break up an AS that small into two seperate private ASes?, it's called thinking outside the box. We tend to think that a small network could not be better served by applying the same principles that we might use for a larger environment. Why is that? Instead of letting the number of devices determine the right solution (Or more properly, a good solution), let's form a solution based on the specific requirements. A network with a small number of devices, but consisting of multiple sites, and redundant links, presents a unique challenge. Forget the number of devices, and look at both the physical topology, and the problem that needs solving. BGPs powerful policy routing tools make it a good fit for this environment, when viewed from a requirements perspective. It's not the only solution, but it is a valid solution, and in my opinion, it's a good solution. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: W. Alan Robertson ; Sent: Tuesday, May 29, 2001 1:02 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Absolutely, but he has traffic going from one router to another, it's not ever exiting the system. ...why would you want to break up an AS that small into two seperate private ASes? besides... the OSPF routes are going to take precedence, not that the admin dist. cant be changed, but ospf is 120, and BGP int routes are 200 (right?) - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 12:42 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, With all due respect, he doesn't have an IGP problem... He has a routing problem, and would like the ability to influence the flow of traffic under certain circumstances to provide for better network performance. After hearing a better explanation of the real issue, path selection for an International site, the use of BGP might go a long way toward solving the issue. He could very simply address his issues by breaking his OSPF into two seperate routing domains, and utilizing BGP as a means of interconnecting them. He could manipulate the traffic through the use of something as simple as AS-path prepending, or the other mechanisms Chuck mentioned (local preference, weight, or meds). Routing protocols are but tools, a simple means to an end. Like all tools, each has it's strengths and weaknesses. Most important is that you select the right one for a given situation. In the absence of more information, the use of BGP sounds like a pretty good solution to the given problem. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: Sent: Tuesday, May 29, 2001 11:29 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] next time you recomend using bgp to fix an IGP problem, im going to.., well, uh, just dont do it again. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6261t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
What about the fact that OSPF will install an Intra-area route over
and Inter-area route regardless of cost?
:)
- Original Message -
From: Hire, Ejay
To:
Sent: Tuesday, May 29, 2001 12:46 PM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Okay, based on all of the information, we can come up with a
solution.
Scenario:
4 routers connected in a ring by various speed links
Objectives:
Router A's traffic for Router C should be sent directly to C
Router B's traffic for Router D should be sent directly to D
Router A's Traffic for B or D should be sent to RouterB
Router B's Traffic for C or A should be sent to RouterB
OSPF should be configured in such a way as to allow the network to
maintain
reachability in the event of any single link failure.
Do as little configuration as possible
Scenario Solution:
See Drawing 1
http://www.miscenterprises.com/schwantz.gif
Meets all of the requirements except for the Do as little work as
possible
because you have to manually configure the cost of every link...
Anyway, you give the FastEthernet Link a low cost, and give the San
Jose-NewYork link a high cost, but not so high that it causes
traffic from D
to C to go D-B-A-C.
If I missed any of the objectives, let me know and I'll wiggle the
numbers
around to make it work.
-Ejay
-Original Message-
From: Kevin Schwantz [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, May 29, 2001 11:38 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Thanks for the recommendations. Firstly, let me explain why I need
the
routing to behave in such a way. The reasons are purely geographical
and I
want to reduce latency. Routers A and B are in London and connected
back to
back via FastEth. Routers C and D are in and SanJose and NewYork
respectively(Connected to both London routers via FR).
I certaintly won't want traffic originating from RouterA ( London )
destined
for RouterD (NewYork) to have to go to SanJose first. It would be
much
better if the hop is A-B-D instead of A-C-D.
Schwantz
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
... or route-map the router D network(s) to go through Router B at
Router
A
- Original Message -
From: Chris Larson
To:
Sent: Tuesday, May 29, 2001 7:24 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Place a summary route to null 0 for the networks on Router D on
your
OSPF
routers and set the metrics appropriately for the summary route
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On
Behalf Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 10:03 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on
the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want
traffic
from
routerA destined for routerD to go via router B. This is not the
case in
my
network because I realise that routerA prefers Intra-Area
routes and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from
routerA to
routerD to go via routerB ? Someone suggested building a GRE
tunnel
between
routerA and routerB and then configure the tunnel to be in
AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0
has been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces
in 3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be
routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual
Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended
Area (even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday
Re: Wanna Be a CCIE? Try This One [7:6076]
I've been looking at the route-maps as well.
Question:
How can the route-map matches tell the difference between the routes
arriving via area 0 and those from area 1. To set the cost of just
those learned from area 1 it would have to be able to tell the
difference.
If you match the RD routes to change the metric wouldn't it change the
metric for both Area 0 and Area 1 RD routes.
Matching the routes then setting the next-hop to RB would give the same
result as the distribute list. (wouldn't it?)
Considering what he wants to do; I would agree that policy routing is
the way to go but do you manipulate the route-map commands?
So far there hasn't been a bullet proof suggestion..
DaveC
Peter I. Slow, CCNP Voice Specialist wrote:
Or use a route-map to increase the path cost...
Otherwise you lose that filtered path as a backup route...
Peter Slow, CCNP Voice Specialist
Network Engineer
Planetary Networks
535 West 34th Street
New York, NY
10001
Cell:(516) 782.1535
Desk: (646) 792.2395
Mail: [EMAIL PROTECTED]
Fax:(646) 792.2396
- Original Message -
From: David Chandler
To:
Sent: Tuesday, May 29, 2001 12:00 PM
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Have you tried an inboud distribution list on Router A's area 1
interfaces. If router A doesn't learn the Router D routes thru those
interfaces it should then use Area 0.
Worth a try.
DaveC
Kevin Schwantz wrote:
Thanks for the recommendations. Firstly, let me explain why I need the
routing to behave in such a way. The reasons are purely geographical
and
I
want to reduce latency. Routers A and B are in London and connected
back
to
back via FastEth. Routers C and D are in and SanJose and NewYork
respectively(Connected to both London routers via FR).
I certaintly won't want traffic originating from RouterA ( London )
destined
for RouterD (NewYork) to have to go to SanJose first. It would be much
better if the hop is A-B-D instead of A-C-D.
Schwantz
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
... or route-map the router D network(s) to go through Router B at
Router
A
- Original Message -
From: Chris Larson
To:
Sent: Tuesday, May 29, 2001 7:24 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Place a summary route to null 0 for the networks on Router D on
your
OSPF
routers and set the metrics appropriately for the summary route
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf
Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 10:03 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want
traffic
from
routerA destined for routerD to go via router B. This is not the
case
in
my
network because I realise that routerA prefers Intra-Area routes
and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA
to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has
been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in
3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be
routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto t
RE: Wanna Be a CCIE? Try This One [7:6076]
No, OSPF is 110. And BGP has 2 ADs. One for IBGP (200) and one for EBGP (20) Christopher A. Kane, CCNP Senior Network Control Tech Router Ops Center/Hilliard NOC UUNET (614)723-7877 -Original Message- From: Peter I. Slow, CCNP Voice Specialist [mailto:[EMAIL PROTECTED]] Sent: Tuesday, May 29, 2001 1:17 PM To: [EMAIL PROTECTED] Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Absolutely, but he has traffic going from one router to another, it's not ever exiting the system. ...why would you want to break up an AS that small into two seperate private ASes? besides... the OSPF routes are going to take precedence, not that the admin dist. cant be changed, but ospf is 120, and BGP int routes are 200 (right?) - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 12:42 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, With all due respect, he doesn't have an IGP problem... He has a routing problem, and would like the ability to influence the flow of traffic under certain circumstances to provide for better network performance. After hearing a better explanation of the real issue, path selection for an International site, the use of BGP might go a long way toward solving the issue. He could very simply address his issues by breaking his OSPF into two seperate routing domains, and utilizing BGP as a means of interconnecting them. He could manipulate the traffic through the use of something as simple as AS-path prepending, or the other mechanisms Chuck mentioned (local preference, weight, or meds). Routing protocols are but tools, a simple means to an end. Like all tools, each has it's strengths and weaknesses. Most important is that you select the right one for a given situation. In the absence of more information, the use of BGP sounds like a pretty good solution to the given problem. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: Sent: Tuesday, May 29, 2001 11:29 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] next time you recomend using bgp to fix an IGP problem, im going to.., well, uh, just dont do it again. FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6264t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
I don`t mean to be the dunce... here but .
why not (and don`t flame me please...)
if you use the ip ospf cost command on the interface you ARE going to
manipulate all traffic
this is going to cause you probs with A-C
IT`s a Doozy kev..i very much wish to find out how your going to get
around this ...
steve
From: Kevin Schwantz
Reply-To: Kevin Schwantz
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Date: Tue, 29 May 2001 12:18:33 -0400
Thats a good point James. Distribution lists are too restrictive and not
very scalable in this situation. I think my first course of action would be
to tweak the OSPF cost between A and C so that traffic from A to D will go
via B instead of C. My only concern is that I might create the situation
where traffic from A destined for C goes via B !! This would just be
creating a new problem.
Kevin
James Haynes wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Wouldn't you still like the route to D to be available through C if the
link
between B and D goes down, or if router B goes down? A distribution list
would stop that.
--
James Haynes
Network Architect
Cendant IT
A+,MCSE,CCNA,CCDA,CCNP,CCDP
David Chandler wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Have you tried an inboud distribution list on Router A's area 1
interfaces. If router A doesn't learn the Router D routes thru those
interfaces it should then use Area 0.
Worth a try.
DaveC
Kevin Schwantz wrote:
Thanks for the recommendations. Firstly, let me explain why I need
the
routing to behave in such a way. The reasons are purely geographical
and
I
want to reduce latency. Routers A and B are in London and connected
back
to
back via FastEth. Routers C and D are in and SanJose and NewYork
respectively(Connected to both London routers via FR).
I certaintly won't want traffic originating from RouterA ( London )
destined
for RouterD (NewYork) to have to go to SanJose first. It would be
much
better if the hop is A-B-D instead of A-C-D.
Schwantz
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
... or route-map the router D network(s) to go through Router B at
Router
A
- Original Message -
From: Chris Larson
To:
Sent: Tuesday, May 29, 2001 7:24 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Place a summary route to null 0 for the networks on Router D on
your
OSPF
routers and set the metrics appropriately for the summary route
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On
Behalf
Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 10:03 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on
the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want
traffic
from
routerA destined for routerD to go via router B. This is not the
case
in
my
network because I realise that routerA prefers Intra-Area
routes
and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from
routerA
to
routerD to go via routerB ? Someone suggested building a GRE
tunnel
between
routerA and routerB and then configure the tunnel to be in
AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0
has
been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces
in
3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be
routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [
Re: Wanna Be a CCIE? Try This One [7:6076]
Peter Slow, CCNP Voice Specialist Network Engineer Planetary Networks 535 West 34th Street New York, NY 10001 Cell:(516) 782.1535 Desk: (646) 792.2395 Mail: [EMAIL PROTECTED] Fax:(646) 792.2396 - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 1:39 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, OSPF has a distance of 110, and yes, iBGP has a distance of 200. By having seperate routing domains for North America and Europe, he could use eBGP (Distance - 20) between his two networks. Distance wouldn't really do anything in this case, though, because European routes would not be learned via OSPF (Remember, we have theoretically split OSPF into two seperate routing domains, never the two shall meet). Instead, eBGP would be bridging the gap between the two OSPF networks. This would afford the opportunity to really take control of what routes were advertised between the two, and excercise strict control of the routing metrics, manipulating them in such a way as to ensure that the best path across the pond were utilized under all normal circumstances, but providing the redundant less preferred path in the event of some kind of outage. Can the same be accomplished via OSPF? Yes, but because we're dealing with Intra-area, and Inter-area routes, it may be more complex than by simply manipulating the link costs. Remember that OSPF chooses an Intra-area route with a Cost of 4,000,000 over an Inter-area route with a cost of 100. That's just one of the quirks of the protocol. As for Why would you want to break up an AS that small into two seperate private ASes?, it's called thinking outside the box. ...Watch it, spanky. We tend to think that a small network could not be better served by applying the same principles that we might use for a larger environment. Why is that? Instead of letting the number of devices determine the right solution (Or more properly, a good solution), let's form a solution based on the specific requirements. A network with a small number of devices, but consisting of multiple sites, and redundant links, presents a unique challenge. Forget the number of devices, and look at both the physical topology, and the problem that needs solving. BGPs powerful policy routing tools make it a good fit for this environment, when viewed from a requirements perspective. I think BGP is completely unecessary in this case.YES, splitting it into two ASes ans using eBGP would work (well), but i really think that modifying the path cost would be the right solution. remember that i never said eBGP wouldnt work. the initial discussion was about using BGP to do this in a SINGLE AS. ...don't get all in a tizzy, i recognize that you have a good idea. I just don't like it =P /me ducks It's not the only solution, but it is a valid solution, and in my opinion, it's a good solution. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: W. Alan Robertson ; Sent: Tuesday, May 29, 2001 1:02 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Absolutely, but he has traffic going from one router to another, it's not ever exiting the system. ...why would you want to break up an AS that small into two seperate private ASes? besides... the OSPF routes are going to take precedence, not that the admin dist. cant be changed, but ospf is 120, and BGP int routes are 200 (right?) - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 12:42 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, With all due respect, he doesn't have an IGP problem... He has a routing problem, and would like the ability to influence the flow of traffic under certain circumstances to provide for better network performance. After hearing a better explanation of the real issue, path selection for an International site, the use of BGP might go a long way toward solving the issue. He could very simply address his issues by breaking his OSPF into two seperate routing domains, and utilizing BGP as a means of interconnecting them. He could manipulate the traffic through the use of something as simple as AS-path prepending, or the other mechanisms Chuck mentioned (local preference, weight, or meds). Routing protocols are but tools, a simple means to an end. Like all tools, each has it's strengths and weaknesses. Most important is that you select the right one for a given situation. In the absence of more information, the use of BGP sounds like a pretty good solution to the given problem. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: Sent: Tuesday, May 29, 2001 11:29 AM Subject: Re: Wanna Be a CCIE? Try This One [7
Re: Wanna Be a CCIE? Try This One [7:6076]
ALL RIGHT, LOOK! The OSPF domain probably isn't big enough to demand multiple areas anyway, so just put ALL 4 of the routers in AREA 0, make the matching costs of the common interfaces on RTR A and RTR B lower, and be done with it! ;-) To: Sent: Tuesday, May 29, 2001 10:52 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, OSPF has a distance of 110, and yes, iBGP has a distance of 200. By having seperate routing domains for North America and Europe, he could use eBGP (Distance - 20) between his two networks. Distance wouldn't really do anything in this case, though, because European routes would not be learned via OSPF (Remember, we have theoretically split OSPF into two seperate routing domains, never the two shall meet). Instead, eBGP would be bridging the gap between the two OSPF networks. This would afford the opportunity to really take control of what routes were advertised between the two, and excercise strict control of the routing metrics, manipulating them in such a way as to ensure that the best path across the pond were utilized under all normal circumstances, but providing the redundant less preferred path in the event of some kind of outage. Can the same be accomplished via OSPF? Yes, but because we're dealing with Intra-area, and Inter-area routes, it may be more complex than by simply manipulating the link costs. Remember that OSPF chooses an Intra-area route with a Cost of 4,000,000 over an Inter-area route with a cost of 100. That's just one of the quirks of the protocol. As for Why would you want to break up an AS that small into two seperate private ASes?, it's called thinking outside the box. We tend to think that a small network could not be better served by applying the same principles that we might use for a larger environment. Why is that? Instead of letting the number of devices determine the right solution (Or more properly, a good solution), let's form a solution based on the specific requirements. A network with a small number of devices, but consisting of multiple sites, and redundant links, presents a unique challenge. Forget the number of devices, and look at both the physical topology, and the problem that needs solving. BGPs powerful policy routing tools make it a good fit for this environment, when viewed from a requirements perspective. It's not the only solution, but it is a valid solution, and in my opinion, it's a good solution. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: W. Alan Robertson ; Sent: Tuesday, May 29, 2001 1:02 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Absolutely, but he has traffic going from one router to another, it's not ever exiting the system. ...why would you want to break up an AS that small into two seperate private ASes? besides... the OSPF routes are going to take precedence, not that the admin dist. cant be changed, but ospf is 120, and BGP int routes are 200 (right?) - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 12:42 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, With all due respect, he doesn't have an IGP problem... He has a routing problem, and would like the ability to influence the flow of traffic under certain circumstances to provide for better network performance. After hearing a better explanation of the real issue, path selection for an International site, the use of BGP might go a long way toward solving the issue. He could very simply address his issues by breaking his OSPF into two seperate routing domains, and utilizing BGP as a means of interconnecting them. He could manipulate the traffic through the use of something as simple as AS-path prepending, or the other mechanisms Chuck mentioned (local preference, weight, or meds). Routing protocols are but tools, a simple means to an end. Like all tools, each has it's strengths and weaknesses. Most important is that you select the right one for a given situation. In the absence of more information, the use of BGP sounds like a pretty good solution to the given problem. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: Sent: Tuesday, May 29, 2001 11:29 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] next time you recomend using bgp to fix an IGP problem, im going to.., well, uh, just dont do it again. FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6268t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Re: Wanna Be a CCIE? Try This One [7:6076]
I have not yet begun to tizzy! ;) - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: W. Alan Robertson ; Sent: Tuesday, May 29, 2001 2:16 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] ...don't get all in a tizzy, i recognize that you have a good idea. I just don't like it =P /me ducks Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6272t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
Couple thoughts on this. Cisco's OSPF should prefer intra area routes over
inter unless the administrative distances are modified. By default, as many
have mentioned, they are all set to 110. However, internally, I believe
path cost is the 2nd tie break, with intra beating inter as the first. If
this is the case (which it should be), modifying path costs whether directly
or through other means will not influence the correct behavior. If this
wasn't the case, the default metric calculation would already have traffic
following the correct path as ABD is a lower cost path then ACD. Where they
all in the same area, traffic would flow properly.
Hence, the question is obviously what do you do? In my opinion, the design
does not optimally reflect the constraints of the physical topology. I
assume we are looking at a subset of a larger network inclusive of more
routers? I would suggest a modification in the OSPF configuration or
possible the routing strategy itself may be in order. What is the reasoning
behind not running in a single area? In cases like these, I find we often
spend more time looking for the complex technical kludge instead of stepping
back and asking the now famous question What problem are we(you) trying to
solve?
Pete
*** REPLY SEPARATOR ***
On 5/29/2001 at 11:38 AM Kevin Schwantz wrote:
Thanks for the recommendations. Firstly, let me explain why I need the
routing to behave in such a way. The reasons are purely geographical and I
want to reduce latency. Routers A and B are in London and connected back to
back via FastEth. Routers C and D are in and SanJose and NewYork
respectively(Connected to both London routers via FR).
I certaintly won't want traffic originating from RouterA ( London )
destined
for RouterD (NewYork) to have to go to SanJose first. It would be much
better if the hop is A-B-D instead of A-C-D.
Schwantz
EA Louie wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
... or route-map the router D network(s) to go through Router B at Router
A
- Original Message -
From: Chris Larson
To:
Sent: Tuesday, May 29, 2001 7:24 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
Place a summary route to null 0 for the networks on Router D on your
OSPF
routers and set the metrics appropriately for the summary route
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Kevin Schwantz
Sent: Tuesday, May 29, 2001 10:03 AM
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
routerArouterB
AREA0AREA0
||
routerC routerD
AREA1-AREA1
Since we are on the topic of OSPF, could someone help me out on the
scenario
above?
Routers A and B have interfaces in Area 0 and Area1. I want traffic
from
routerA destined for routerD to go via router B. This is not the case
in
my
network because I realise that routerA prefers Intra-Area routes and
thus
would route traffic to routerD via routerC.
What tweaks must I make in order to force the traffic from routerA to
routerD to go via routerB ? Someone suggested building a GRE tunnel
between
routerA and routerB and then configure the tunnel to be in AREA1.
Any suggestions?
Kevin
W. Alan Robertson wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Guys,
The actual traffic will not be routed up to area 0... Area 0 has
been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3
areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed
directly
by
R2. This satisfies the Interarea traffic must traverse the
backbone
rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked
psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area
(even
if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE list?
The following message came through today. I thought the bright
folks
on
this
list might be curious
Re: Wanna Be a CCIE? Try This One [7:6076]
As Alan correctly points out, path cost is irrelevant in this case as intra area routers will be preferred over inter. We tend to think that a small network could not be better served by applying the same principles that we might use for a larger environment. Why is that? Instead of letting the number of devices determine the right solution (Or more properly, a good solution), let's form a solution based on the specific requirements. A network with a small number of devices, but consisting of multiple sites, and redundant links, presents a unique challenge. Forget the number of devices, and look at both the physical topology, and the problem that needs solving. BGPs powerful policy routing tools make it a good fit for this environment, when viewed from a requirements perspective. I think BGP is completely unecessary in this case.YES, splitting it into two ASes ans using eBGP would work (well), but i really think that modifying the path cost would be the right solution. remember that i never said eBGP wouldnt work. the initial discussion was about using BGP to do this in a SINGLE AS. ...don't get all in a tizzy, i recognize that you have a good idea. I just don't like it =P /me ducks It's not the only solution, but it is a valid solution, and in my opinion, it's a good solution. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: W. Alan Robertson ; Sent: Tuesday, May 29, 2001 1:02 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Absolutely, but he has traffic going from one router to another, it's not ever exiting the system. ...why would you want to break up an AS that small into two seperate private ASes? besides... the OSPF routes are going to take precedence, not that the admin dist. cant be changed, but ospf is 120, and BGP int routes are 200 (right?) - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 12:42 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, With all due respect, he doesn't have an IGP problem... He has a routing problem, and would like the ability to influence the flow of traffic under certain circumstances to provide for better network performance. After hearing a better explanation of the real issue, path selection for an International site, the use of BGP might go a long way toward solving the issue. He could very simply address his issues by breaking his OSPF into two seperate routing domains, and utilizing BGP as a means of interconnecting them. He could manipulate the traffic through the use of something as simple as AS-path prepending, or the other mechanisms Chuck mentioned (local preference, weight, or meds). Routing protocols are but tools, a simple means to an end. Like all tools, each has it's strengths and weaknesses. Most important is that you select the right one for a given situation. In the absence of more information, the use of BGP sounds like a pretty good solution to the given problem. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: Sent: Tuesday, May 29, 2001 11:29 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] next time you recomend using bgp to fix an IGP problem, im going to.., well, uh, just dont do it again. FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6275t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
ALL RIGHT, LOOK! The OSPF domain probably isn't big enough to demand multiple areas anyway, so just put ALL 4 of the routers in AREA 0, make the matching costs of the common interfaces on RTR A and RTR B lower, and be done with it! Please! Nothing wrong with having a single-area OSPF network, but number it ANYTHING except 0.0.0.0. Otherwise, if you ever need a second area, you have to change all your network statements so you can connect to the true backbone. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6294t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
Heh. this is crazy enough it just might work! =^ Mike W. EA Louie wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... ALL RIGHT, LOOK! The OSPF domain probably isn't big enough to demand multiple areas anyway, so just put ALL 4 of the routers in AREA 0, make the matching costs of the common interfaces on RTR A and RTR B lower, and be done with it! ;-) To: Sent: Tuesday, May 29, 2001 10:52 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, OSPF has a distance of 110, and yes, iBGP has a distance of 200. By having seperate routing domains for North America and Europe, he could use eBGP (Distance - 20) between his two networks. Distance wouldn't really do anything in this case, though, because European routes would not be learned via OSPF (Remember, we have theoretically split OSPF into two seperate routing domains, never the two shall meet). Instead, eBGP would be bridging the gap between the two OSPF networks. This would afford the opportunity to really take control of what routes were advertised between the two, and excercise strict control of the routing metrics, manipulating them in such a way as to ensure that the best path across the pond were utilized under all normal circumstances, but providing the redundant less preferred path in the event of some kind of outage. Can the same be accomplished via OSPF? Yes, but because we're dealing with Intra-area, and Inter-area routes, it may be more complex than by simply manipulating the link costs. Remember that OSPF chooses an Intra-area route with a Cost of 4,000,000 over an Inter-area route with a cost of 100. That's just one of the quirks of the protocol. As for Why would you want to break up an AS that small into two seperate private ASes?, it's called thinking outside the box. We tend to think that a small network could not be better served by applying the same principles that we might use for a larger environment. Why is that? Instead of letting the number of devices determine the right solution (Or more properly, a good solution), let's form a solution based on the specific requirements. A network with a small number of devices, but consisting of multiple sites, and redundant links, presents a unique challenge. Forget the number of devices, and look at both the physical topology, and the problem that needs solving. BGPs powerful policy routing tools make it a good fit for this environment, when viewed from a requirements perspective. It's not the only solution, but it is a valid solution, and in my opinion, it's a good solution. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: W. Alan Robertson ; Sent: Tuesday, May 29, 2001 1:02 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Absolutely, but he has traffic going from one router to another, it's not ever exiting the system. ...why would you want to break up an AS that small into two seperate private ASes? besides... the OSPF routes are going to take precedence, not that the admin dist. cant be changed, but ospf is 120, and BGP int routes are 200 (right?) - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 12:42 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, With all due respect, he doesn't have an IGP problem... He has a routing problem, and would like the ability to influence the flow of traffic under certain circumstances to provide for better network performance. After hearing a better explanation of the real issue, path selection for an International site, the use of BGP might go a long way toward solving the issue. He could very simply address his issues by breaking his OSPF into two seperate routing domains, and utilizing BGP as a means of interconnecting them. He could manipulate the traffic through the use of something as simple as AS-path prepending, or the other mechanisms Chuck mentioned (local preference, weight, or meds). Routing protocols are but tools, a simple means to an end. Like all tools, each has it's strengths and weaknesses. Most important is that you select the right one for a given situation. In the absence of more information, the use of BGP sounds like a pretty good solution to the given problem. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: Sent: Tuesday, May 29, 2001 11:29 AM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] next time you recomend using bgp to fix an IGP problem, im going to.., well, uh, just dont do it again. FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report mi
Re: Wanna Be a CCIE? Try This One [7:6076]
I would have to agree...Given that there are 2 European sites and 2 US sites, I think the overhead of BGP would be negligible, while at the same time providing a graceful solution to a sticky problem. I think you stated your point very well that, even tho the network may seem small, the fact there are multiple sites with redundant links makes the network more complex like a large network, no matter how many actual routers, end PCs, etc. Using BGP (eBGP treating the 2 networks on each continent as a different BGP AS) would definitely make things simpiler to manage while giving more control using routing policies and prefix lists. CCNP BSCN Question #1: When to use BGP? (two of the possible answers) 1) When the flow of traffic entering and leaving an AS must be manipulated. 2) When the AS has multiple connections to another AS. Breaking the 2 London routers into an AS and the two US routers into an AS, it seems to me being able to maniuplate the routes between the 2 continents' ASes would be convenient and fits the purpose of BGP very nicely. But also consider: CCNP BSCN Question #2: When NOT to use BGP? (three of the possible answers) 1) Low bandwidth between ASes. 2) Lack of memory/CPU power on those routers 3) A limited understanding of BGP route filtering and selection. Kevin: What are the speed of the links between New York/London and San Jose/London? Can the routers at each site handle running BGP? Do you understand BGP and route filtering? If the links aren't too tiny, the routers can handle it, and you understand how to implement BGP route filtering, this BGP solution doesn't sound bad to me My 2 cents. Mike W. W. Alan Robertson wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Peter, OSPF has a distance of 110, and yes, iBGP has a distance of 200. By having seperate routing domains for North America and Europe, he could use eBGP (Distance - 20) between his two networks. Distance wouldn't really do anything in this case, though, because European routes would not be learned via OSPF (Remember, we have theoretically split OSPF into two seperate routing domains, never the two shall meet). Instead, eBGP would be bridging the gap between the two OSPF networks. This would afford the opportunity to really take control of what routes were advertised between the two, and excercise strict control of the routing metrics, manipulating them in such a way as to ensure that the best path across the pond were utilized under all normal circumstances, but providing the redundant less preferred path in the event of some kind of outage. Can the same be accomplished via OSPF? Yes, but because we're dealing with Intra-area, and Inter-area routes, it may be more complex than by simply manipulating the link costs. Remember that OSPF chooses an Intra-area route with a Cost of 4,000,000 over an Inter-area route with a cost of 100. That's just one of the quirks of the protocol. As for Why would you want to break up an AS that small into two seperate private ASes?, it's called thinking outside the box. We tend to think that a small network could not be better served by applying the same principles that we might use for a larger environment. Why is that? Instead of letting the number of devices determine the right solution (Or more properly, a good solution), let's form a solution based on the specific requirements. A network with a small number of devices, but consisting of multiple sites, and redundant links, presents a unique challenge. Forget the number of devices, and look at both the physical topology, and the problem that needs solving. BGPs powerful policy routing tools make it a good fit for this environment, when viewed from a requirements perspective. It's not the only solution, but it is a valid solution, and in my opinion, it's a good solution. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: W. Alan Robertson ; Sent: Tuesday, May 29, 2001 1:02 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Absolutely, but he has traffic going from one router to another, it's not ever exiting the system. ...why would you want to break up an AS that small into two seperate private ASes? besides... the OSPF routes are going to take precedence, not that the admin dist. cant be changed, but ospf is 120, and BGP int routes are 200 (right?) - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 12:42 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, With all due respect, he doesn't have an IGP problem... He has a routing problem, and would like the ability to influence the flow of traffic under certain circumstances to provide for better network performance. After hearing a better explanation of the real issue, path s
Re: Wanna Be a CCIE? Try This One [7:6076]
/me swallows his pride and seconds the motion. -Peter Slow, CCNBlah - Original Message - From: Michael L. Williams To: Sent: Tuesday, May 29, 2001 7:52 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] I would have to agree...Given that there are 2 European sites and 2 US sites, I think the overhead of BGP would be negligible, while at the same time providing a graceful solution to a sticky problem. I think you stated your point very well that, even tho the network may seem small, the fact there are multiple sites with redundant links makes the network more complex like a large network, no matter how many actual routers, end PCs, etc. Using BGP (eBGP treating the 2 networks on each continent as a different BGP AS) would definitely make things simpiler to manage while giving more control using routing policies and prefix lists. CCNP BSCN Question #1: When to use BGP? (two of the possible answers) 1) When the flow of traffic entering and leaving an AS must be manipulated. 2) When the AS has multiple connections to another AS. Breaking the 2 London routers into an AS and the two US routers into an AS, it seems to me being able to maniuplate the routes between the 2 continents' ASes would be convenient and fits the purpose of BGP very nicely. But also consider: CCNP BSCN Question #2: When NOT to use BGP? (three of the possible answers) 1) Low bandwidth between ASes. 2) Lack of memory/CPU power on those routers 3) A limited understanding of BGP route filtering and selection. Kevin: What are the speed of the links between New York/London and San Jose/London? Can the routers at each site handle running BGP? Do you understand BGP and route filtering? If the links aren't too tiny, the routers can handle it, and you understand how to implement BGP route filtering, this BGP solution doesn't sound bad to me My 2 cents. Mike W. W. Alan Robertson wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Peter, OSPF has a distance of 110, and yes, iBGP has a distance of 200. By having seperate routing domains for North America and Europe, he could use eBGP (Distance - 20) between his two networks. Distance wouldn't really do anything in this case, though, because European routes would not be learned via OSPF (Remember, we have theoretically split OSPF into two seperate routing domains, never the two shall meet). Instead, eBGP would be bridging the gap between the two OSPF networks. This would afford the opportunity to really take control of what routes were advertised between the two, and excercise strict control of the routing metrics, manipulating them in such a way as to ensure that the best path across the pond were utilized under all normal circumstances, but providing the redundant less preferred path in the event of some kind of outage. Can the same be accomplished via OSPF? Yes, but because we're dealing with Intra-area, and Inter-area routes, it may be more complex than by simply manipulating the link costs. Remember that OSPF chooses an Intra-area route with a Cost of 4,000,000 over an Inter-area route with a cost of 100. That's just one of the quirks of the protocol. As for Why would you want to break up an AS that small into two seperate private ASes?, it's called thinking outside the box. We tend to think that a small network could not be better served by applying the same principles that we might use for a larger environment. Why is that? Instead of letting the number of devices determine the right solution (Or more properly, a good solution), let's form a solution based on the specific requirements. A network with a small number of devices, but consisting of multiple sites, and redundant links, presents a unique challenge. Forget the number of devices, and look at both the physical topology, and the problem that needs solving. BGPs powerful policy routing tools make it a good fit for this environment, when viewed from a requirements perspective. It's not the only solution, but it is a valid solution, and in my opinion, it's a good solution. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: W. Alan Robertson ; Sent: Tuesday, May 29, 2001 1:02 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Absolutely, but he has traffic going from one router to another, it's not ever exiting the system. ...why would you want to break up an AS that small into two seperate private ASes? besides... the OSPF routes are going to take precedence, not that the admin dist. cant be changed, but ospf is 120, and BGP int routes are 200 (right?) - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 12:42 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Re: Wanna Be a CCIE? Try This One [7:6076]
I would have to agree...Given that there are 2 European sites and 2 US sites, I think the overhead of BGP would be negligible, while at the same time providing a graceful solution to a sticky problem. I think you stated your point very well that, even tho the network may seem small, the fact there are multiple sites with redundant links makes the network more complex like a large network, no matter how many actual routers, end PCs, etc. Using BGP (eBGP treating the 2 networks on each continent as a different BGP AS) would definitely make things simpiler to manage while giving more control using routing policies and prefix lists. CCNP BSCN Question #1: When to use BGP? (two of the possible answers) 1) When the flow of traffic entering and leaving an AS must be manipulated. 2) When the AS has multiple connections to another AS. Breaking the 2 London routers into an AS and the two US routers into an AS, it seems to me being able to maniuplate the routes between the 2 continents' ASes would be convenient and fits the purpose of BGP very nicely. But also consider: CCNP BSCN Question #2: When NOT to use BGP? (three of the possible answers) 1) Low bandwidth between ASes. 2) Lack of memory/CPU power on those routers 3) A limited understanding of BGP route filtering and selection. This question confuses running BGP, I think, with running BGP with full routes. For a relatively small number of routes, OSPF is more CPU intensive than BGP. OSPF hellos and such also consume more bandwidth. #3 is valid. Kevin: What are the speed of the links between New York/London and San Jose/London? Can the routers at each site handle running BGP? Do you understand BGP and route filtering? If the links aren't too tiny, the routers can handle it, and you understand how to implement BGP route filtering, this BGP solution doesn't sound bad to me My 2 cents. Mike W. W. Alan Robertson wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Peter, OSPF has a distance of 110, and yes, iBGP has a distance of 200. By having seperate routing domains for North America and Europe, he could use eBGP (Distance - 20) between his two networks. Distance wouldn't really do anything in this case, though, because European routes would not be learned via OSPF (Remember, we have theoretically split OSPF into two seperate routing domains, never the two shall meet). Instead, eBGP would be bridging the gap between the two OSPF networks. This would afford the opportunity to really take control of what routes were advertised between the two, and excercise strict control of the routing metrics, manipulating them in such a way as to ensure that the best path across the pond were utilized under all normal circumstances, but providing the redundant less preferred path in the event of some kind of outage. Can the same be accomplished via OSPF? Yes, but because we're dealing with Intra-area, and Inter-area routes, it may be more complex than by simply manipulating the link costs. Remember that OSPF chooses an Intra-area route with a Cost of 4,000,000 over an Inter-area route with a cost of 100. That's just one of the quirks of the protocol. As for Why would you want to break up an AS that small into two seperate private ASes?, it's called thinking outside the box. We tend to think that a small network could not be better served by applying the same principles that we might use for a larger environment. Why is that? Instead of letting the number of devices determine the right solution (Or more properly, a good solution), let's form a solution based on the specific requirements. A network with a small number of devices, but consisting of multiple sites, and redundant links, presents a unique challenge. Forget the number of devices, and look at both the physical topology, and the problem that needs solving. BGPs powerful policy routing tools make it a good fit for this environment, when viewed from a requirements perspective. It's not the only solution, but it is a valid solution, and in my opinion, it's a good solution. Alan - Original Message - From: Peter I. Slow, CCNP Voice Specialist To: W. Alan Robertson ; Sent: Tuesday, May 29, 2001 1:02 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Absolutely, but he has traffic going from one router to another, it's not ever exiting the system. ...why would you want to break up an AS that small into two seperate private ASes? besides... the OSPF routes are going to take precedence, not that the admin dist. cant be changed, but ospf is 120, and BGP int routes are 200 (right?) - Original Message - From: W. Alan Robertson To: Peter I. Slow, CCNP Voice Specialist ; Sent: Tuesday, May 29, 2001 12:42 PM Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Peter, With all due res
Re: Wanna Be a CCIE? Try This One [7:6076]
Hey Chuck.. I just thought of something. you only need 2
routers to have 3 OSPF Areas in your diagram you show a router inside
each OSPF area, however, OSPF routers (at least in my understanding and most
Cisco Press book diagrams) are either totally inside an area (all interfaces
inside a single Area, although they may connect elsewhere using other
routing protocols, we're only considering OSPF) or sit on the edge of
multiple areas (ABRs). Having said that, I would think the problem now
becomes one like this: (please excuse my ASCII drawing skills =)
| Area 0 | | Area 1 | | Area 2 |
| R1 R2 |
| ___| || |___|
The Virtual Link is now between R2 and R1. In this new scenario, there is
no issue about where the traffic destined for Area 1 goes (it goes to R1).
Can you further explain the scenario you speak of with 3 OSPF Areas with a
router in each Area?That sounds more like a BGP thing where a router is
inside an AS but can connect to routers in other ASes (via eBGP) without
being part of the other AS.
Mike W.
Chuck Larrieu wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Ever wonder what the CCIE candidates talk about on the CCIE list?
The following message came through today. I thought the bright folks on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on Virtual
Links in OSPF. It was posted some time ago but I can't seem to find it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic needs to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link has to
use R1 (To create the V.Link). Does the traffic flow passed R1 (in Area 1)
to Area 0 and then back to area 1, or does the actual flow just to R1 from
R2.
I cant remember the conclusion, and I cant seem to find it on the
archives.
Quite interesting issues.
End of original question
Chuck
One IOS to forward them all.
One IOS to find them.
One IOS to summarize them all
And in the routing table bind them.
-JRR Chambers-
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Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked psuedo-ABR passes back to Area 0, before it's sent onto the intended Area (even if it's directly connected). Phil - Original Message - From: Chuck Larrieu To: Sent: Sunday, May 27, 2001 8:59 PM Subject: Wanna Be a CCIE? Try This One [7:6076] Ever wonder what the CCIE candidates talk about on the CCIE list? The following message came through today. I thought the bright folks on this list might be curious, and might want to venture an answer. Begin original question: Guys, I wonder if there is anybody who remembers the discussion on Virtual Links in OSPF. It was posted some time ago but I can't seem to find it. The scenario was something like this: ___ ___ |Area 0 | |Area1||Area2| |R0|--| R1 |--| R2 | |__| |_||_| There is a virtual link from area 2 to Area 0 via Area1. Traffic needs to get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link has to use R1 (To create the V.Link). Does the traffic flow passed R1 (in Area 1) to Area 0 and then back to area 1, or does the actual flow just to R1 from R2. I cant remember the conclusion, and I cant seem to find it on the archives. Quite interesting issues. End of original question Chuck One IOS to forward them all. One IOS to find them. One IOS to summarize them all And in the routing table bind them. -JRR Chambers- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6108t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area -Original Message- From: Circusnuts [mailto:[EMAIL PROTECTED]] Sent: 28 May 2001 15:50 To: [EMAIL PROTECTED] Subject: Re: Wanna Be a CCIE? Try This One [7:6076] Chuck- my answer is Yes. The traffic from the Virtual Linked psuedo-ABR passes back to Area 0, before it's sent onto the intended Area (even if it's directly connected). Phil - Original Message - From: Chuck Larrieu To: Sent: Sunday, May 27, 2001 8:59 PM Subject: Wanna Be a CCIE? Try This One [7:6076] Ever wonder what the CCIE candidates talk about on the CCIE list? The following message came through today. I thought the bright folks on this list might be curious, and might want to venture an answer. Begin original question: Guys, I wonder if there is anybody who remembers the discussion on Virtual Links in OSPF. It was posted some time ago but I can't seem to find it. The scenario was something like this: ___ ___ |Area 0 | |Area1||Area2| |R0|--| R1 |--| R2 | |__| |_||_| There is a virtual link from area 2 to Area 0 via Area1. Traffic needs to get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link has to use R1 (To create the V.Link). Does the traffic flow passed R1 (in Area 1) to Area 0 and then back to area 1, or does the actual flow just to R1 from R2. I cant remember the conclusion, and I cant seem to find it on the archives. Quite interesting issues. End of original question Chuck One IOS to forward them all. One IOS to find them. One IOS to summarize them all And in the routing table bind them. -JRR Chambers- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6110t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wanna Be a CCIE? Try This One [7:6076]
Guys,
The actual traffic will not be routed up to area 0... Area 0 has been
extended
down to R2, so R2 is now a backbone router. R2 has interfaces in 3 areas
now:
Area1, Area2, and Area0 by means of it's virtual link.
Any traffic originating in Area2 destined for Area1 will be routed directly
by
R2. This satisfies the Interarea traffic must traverse the backbone rule,
because R2 *is* a backbone router.
This is not theory... It is fact.
Alan
- Original Message -
From: Andrew Larkins
To:
Sent: Monday, May 28, 2001 10:13 AM
Subject: RE: Wanna Be a CCIE? Try This One [7:6076]
agreedto area 0 then on to the intended area
-Original Message-
From: Circusnuts [mailto:[EMAIL PROTECTED]]
Sent: 28 May 2001 15:50
To: [EMAIL PROTECTED]
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck- my answer is Yes. The traffic from the Virtual Linked psuedo-ABR
passes back to Area 0, before it's sent onto the intended Area (even if
it's
directly connected).
Phil
- Original Message -
From: Chuck Larrieu
To:
Sent: Sunday, May 27, 2001 8:59 PM
Subject: Wanna Be a CCIE? Try This One [7:6076]
Ever wonder what the CCIE candidates talk about on the CCIE list?
The following message came through today. I thought the bright folks on
this
list might be curious, and might want to venture an answer.
Begin original question:
Guys,
I wonder if there is anybody who remembers the discussion on Virtual
Links in OSPF. It was posted some time ago but I can't seem to find it.
The scenario was something like this:
___ ___
|Area 0 | |Area1||Area2|
|R0|--| R1 |--| R2 |
|__| |_||_|
There is a virtual link from area 2 to Area 0 via Area1. Traffic needs to
get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link has
to
use R1 (To create the V.Link). Does the traffic flow passed R1 (in Area
1)
to Area 0 and then back to area 1, or does the actual flow just to R1
from
R2.
I cant remember the conclusion, and I cant seem to find it on the
archives.
Quite interesting issues.
End of original question
Chuck
One IOS to forward them all.
One IOS to find them.
One IOS to summarize them all
And in the routing table bind them.
-JRR Chambers-
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
FAQ, list archives, and subscription info:
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Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7i=6117t=6076
--
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Re: Wanna Be a CCIE? Try This One [7:6076]
Chuck, Is that what set off the great Virtual link thread, which I might add, has become quite heated? I was just skimming the list for the past couple of days, so I didn't really catch the beginning. I'm not sure it's been resolved yet, but I know the answer to the question if that's of any interest. It's kind of a trick question... In OSPF, traffic between two non-zero areas (such as area1 and area2 in the diagram below) must traverse the backbone, area0. This is a special circumstance though, because router2 is virtually linked to area0, since it doesn't have a direct connection. The end result is that traffic between areas 1 and 2 does pass through area0, but not in the way most people think. R2 is a backbone router, by virtue of it's virtual link, so it may pass traffic between areas1 and 2 directly. This does not break any rules, and is in fact a desired behavior. Alan - Original Message - From: Chuck Larrieu To: Sent: Sunday, May 27, 2001 8:59 PM Subject: Wanna Be a CCIE? Try This One [7:6076] Ever wonder what the CCIE candidates talk about on the CCIE list? The following message came through today. I thought the bright folks on this list might be curious, and might want to venture an answer. Begin original question: Guys, I wonder if there is anybody who remembers the discussion on Virtual Links in OSPF. It was posted some time ago but I can't seem to find it. The scenario was something like this: ___ ___ |Area 0 | |Area1||Area2| |R0|--| R1 |--| R2 | |__| |_||_| There is a virtual link from area 2 to Area 0 via Area1. Traffic needs to get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link has to use R1 (To create the V.Link). Does the traffic flow passed R1 (in Area 1) to Area 0 and then back to area 1, or does the actual flow just to R1 from R2. I cant remember the conclusion, and I cant seem to find it on the archives. Quite interesting issues. End of original question Chuck One IOS to forward them all. One IOS to find them. One IOS to summarize them all And in the routing table bind them. -JRR Chambers- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=6085t=6076 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
