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.
>> routerA routerB
>> AREA0 5-------- 5 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]...
>> > > > routerA routerB
>> > > > AREA0--------AREA0
>> > > > | |
>> > > > 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]
>> > > > >
>> > > > >
>> > > > > > agreed....to 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:
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>> > > > Report misconduct and Nondisclosure violations to
>[EMAIL PROTECTED]
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>[EMAIL PROTECTED]
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>>
>> ***>
>>
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