Re: OSPF Stub area [7:52781]
Your stub router will take the shortest path to the destinations in area 0. In this case, it will sum the cost from the ABR to the destination (assuming area 0 destination) with the cost of itself to the ABR(s) and take the lower cost of the candidate paths. In your case, simply increase the metric on the link toward the vpn and you should see the proper primary/secondary paths. Pete At 11:00 AM 9/6/2002 +, Lee Messenger wrote: >Hi, > >I have a network (Area 3) that has 2 connections to my OSPF area 0. One via >2mb ATM the other via VPN. I would like to configure this as a stub area, >however, with multiple exit points, will my traffic go via the ATM or VPN or >both. I would prefer the route via ATM, and only use VPN if ATM goes down. >What do I need to do to achive this ? > >Regards > >LM Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=52799&t=52781 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF Stub area [7:52781]
Might also want to consider changing the cost at the ABR using 'ip ospf cost'. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Casey, Paul (6822) Sent: Friday, September 06, 2002 10:03 PM To: [EMAIL PROTECTED] Subject: Re: OSPF Stub area [7:52781] Use the area 3 default command on the abr router you want the traffic to go over, this will get injected into the stub area Both Abr's will inject 0.0.0.0 in to the stub, buf you can influence using this command.. Which will be the prefered route out, + u could also use the summary command on the other router for certain traffic to go through this one Kind regards. Paul. -- Sent from my BlackBerry Wireless Handheld -Original Message- From: Lee Messenger To: [EMAIL PROTECTED] Sent: Fri Sep 06 12:00:36 2002 Subject: OSPF Stub area [7:52781] Hi, I have a network (Area 3) that has 2 connections to my OSPF area 0. One via 2mb ATM the other via VPN. I would like to configure this as a stub area, however, with multiple exit points, will my traffic go via the ATM or VPN or both. I would prefer the route via ATM, and only use VPN if ATM goes down. What do I need to do to achive this ? Regards LM This E-mail is from O2. The E-mail and any files transmitted with it are confidential and may also be privileged and intended solely for the use of the individual or entity to whom they are addressed. Any unauthorised direct or indirect dissemination, distribution or copying of this message and any attachments is strictly prohibited. If you have received the E-mail in error please notify [EMAIL PROTECTED] or telephone ++ 353 1 6095000. * Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=52793&t=52781 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Stub area [7:52781]
Paul, Thanks for the reply, I think you may have misunderstood my network topology. Illustrated below Area0RouterAArea3RouterB Both the ATM link and VPN begin and end at the above routers(via different interfaces) Therefore if Area 3 is a stub (or totally stubby), router B will have 2 0.0.0.0 routes to the networks in Area 0. My question is, which interface will traffic from router B go over when going to destinations in Area0. I believe it will prefer the ATM over the tunnel interface because Tunnel interfaces have a higher cost. Although I'm a bit unsure Hope this makes things clearer LM Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=52790&t=52781 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Stub area [7:52781]
Use the area 3 default command on the abr router you want the traffic to go over, this will get injected into the stub area Both Abr's will inject 0.0.0.0 in to the stub, buf you can influence using this command.. Which will be the prefered route out, + u could also use the summary command on the other router for certain traffic to go through this one Kind regards. Paul. -- Sent from my BlackBerry Wireless Handheld -Original Message- From: Lee Messenger To: [EMAIL PROTECTED] Sent: Fri Sep 06 12:00:36 2002 Subject: OSPF Stub area [7:52781] Hi, I have a network (Area 3) that has 2 connections to my OSPF area 0. One via 2mb ATM the other via VPN. I would like to configure this as a stub area, however, with multiple exit points, will my traffic go via the ATM or VPN or both. I would prefer the route via ATM, and only use VPN if ATM goes down. What do I need to do to achive this ? Regards LM This E-mail is from O2. The E-mail and any files transmitted with it are confidential and may also be privileged and intended solely for the use of the individual or entity to whom they are addressed. Any unauthorised direct or indirect dissemination, distribution or copying of this message and any attachments is strictly prohibited. If you have received the E-mail in error please notify [EMAIL PROTECTED] or telephone ++ 353 1 6095000. * Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=52784&t=52781 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
OSPF Stub area [7:52781]
Hi, I have a network (Area 3) that has 2 connections to my OSPF area 0. One via 2mb ATM the other via VPN. I would like to configure this as a stub area, however, with multiple exit points, will my traffic go via the ATM or VPN or both. I would prefer the route via ATM, and only use VPN if ATM goes down. What do I need to do to achive this ? Regards LM Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=52781&t=52781 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Stub area and Default Cost [7:33905]
The BSCN book mentions... if the area stub default cost is not configured, the router advertises 0.0.0.0 with a default cost metric of 1 plus any internal costs. Q: Isn't the default metric a Type 2? Or is a stub area an exception? R3# int e0 ip add 192.168.14.1 255.255.255.0 int s0 ip add 192.168.15.1 255.255.255.252 router ospf 100 net 192.169.14.0 0.0.0.255 area 0 net 192.168.15.0 0.0.0.255 area 2 area 2 stub R4# int s0 ip add 192.168.15.2 255.255.255.252 router ospf 15 net 192.168.15.0 0.0.0.255 area 2 area 2 stub (page 193) Thanks for the help. Elmer Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=33905&t=33905 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Stub area question [7:1112]
sorry all, more typo's on my behalf. the default route points to the inter area and beyond. *** REPLY SEPARATOR *** On 4/18/2001 at 2:30 PM Peter Van Oene wrote: >Keep in mind that all routers within any type of ospf area must maintain >identical link state databases. Hence, you will see all intra area routes >and a default route toward intra-area and beyond. > >Pete > > >*** REPLY SEPARATOR *** > >On 4/18/2001 at 1:47 PM Coleman, Jason wrote: > >>Consider the following scenario: >> >>Two HQ routers that have 2 sites each connected to them over frame relay >>point-to-point sub-interfaces. >>The two HQ routers are on the same LAN. These Ethernet ports are in Area >>0. >> >>The HQ1 WAN links and their sites are in Area 1, and the HQ2 WAN links and >>their sites are in Area 2. >>Both Area 1 and Area 2 are setup to be totally stubby areas. >> >>When looking at the routing table for a remote site connected to HQ1, will >>you see only a default route or will you see a default route and the >routes >>for the other remote site in Area 1? >> >>I have been taken course and been led to believe that there should only be >>a >>default route, but I read a white paper the other day, and it indicated >>that >>you will see all Intra-area routes. To me, that means that I should see >>routes to the other networks within my own area. >> >>I am working on setting this up as well to see it work for myself, but >>interested in any input. >> >>Thanks, >> >>Jason Coleman - CCNP, CCDP >>Customer Engineer >>Network Management Center - Austin >>(ph) 512-340-3134 >>(email) [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=7&i=1159&t=1112 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Stub area question [7:1112]
As I understand it: For any given area, all routers with interfaces in that area will have identical link state databases; therefore, their routing tables would contain entries for routes within the area. Intra-area updates are type 1 and 2 LSAs. Inter-area updates are type 3 and 4. Updates from external AS are LSA type 5. A stubby area will not accept type 5 LSAs (from ASBRs) but will accept all others; in place of the type 5 LSAs the ABR will advertise a default route pointing to the ASBR. A totally stubby area will not accept types 3, 4, or 5. It will accept types 1 and 2, so it will have full knowledge of intra-area routes, but it will have a default for all routes outside of its area. I hope that makes sense, my explainer isn't working very well at the moment. John >>> "Coleman, Jason" 4/18/01 11:47:43 AM >>> Consider the following scenario: Two HQ routers that have 2 sites each connected to them over frame relay point-to-point sub-interfaces. The two HQ routers are on the same LAN. These Ethernet ports are in Area 0. The HQ1 WAN links and their sites are in Area 1, and the HQ2 WAN links and their sites are in Area 2. Both Area 1 and Area 2 are setup to be totally stubby areas. When looking at the routing table for a remote site connected to HQ1, will you see only a default route or will you see a default route and the routes for the other remote site in Area 1? I have been taken course and been led to believe that there should only be a default route, but I read a white paper the other day, and it indicated that you will see all Intra-area routes. To me, that means that I should see routes to the other networks within my own area. I am working on setting this up as well to see it work for myself, but interested in any input. Thanks, Jason Coleman - CCNP, CCDP Customer Engineer Network Management Center - Austin (ph) 512-340-3134 (email) [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=7&i=1126&t=1112 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Stub area question [7:1112]
Keep in mind that all routers within any type of ospf area must maintain identical link state databases. Hence, you will see all intra area routes and a default route toward intra-area and beyond. Pete *** REPLY SEPARATOR *** On 4/18/2001 at 1:47 PM Coleman, Jason wrote: >Consider the following scenario: > >Two HQ routers that have 2 sites each connected to them over frame relay >point-to-point sub-interfaces. >The two HQ routers are on the same LAN. These Ethernet ports are in Area >0. > >The HQ1 WAN links and their sites are in Area 1, and the HQ2 WAN links and >their sites are in Area 2. >Both Area 1 and Area 2 are setup to be totally stubby areas. > >When looking at the routing table for a remote site connected to HQ1, will >you see only a default route or will you see a default route and the routes >for the other remote site in Area 1? > >I have been taken course and been led to believe that there should only be >a >default route, but I read a white paper the other day, and it indicated >that >you will see all Intra-area routes. To me, that means that I should see >routes to the other networks within my own area. > >I am working on setting this up as well to see it work for myself, but >interested in any input. > >Thanks, > >Jason Coleman - CCNP, CCDP >Customer Engineer >Network Management Center - Austin >(ph) 512-340-3134 >(email) [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=7&i=1119&t=1112 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
OSPF Stub area question [7:1112]
Consider the following scenario: Two HQ routers that have 2 sites each connected to them over frame relay point-to-point sub-interfaces. The two HQ routers are on the same LAN. These Ethernet ports are in Area 0. The HQ1 WAN links and their sites are in Area 1, and the HQ2 WAN links and their sites are in Area 2. Both Area 1 and Area 2 are setup to be totally stubby areas. When looking at the routing table for a remote site connected to HQ1, will you see only a default route or will you see a default route and the routes for the other remote site in Area 1? I have been taken course and been led to believe that there should only be a default route, but I read a white paper the other day, and it indicated that you will see all Intra-area routes. To me, that means that I should see routes to the other networks within my own area. I am working on setting this up as well to see it work for myself, but interested in any input. Thanks, Jason Coleman - CCNP, CCDP Customer Engineer Network Management Center - Austin (ph) 512-340-3134 (email) [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=1112&t=1112 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Which LSA type is NOT allowed in the Stub Area?
answer is D. For totally stubby it will be C and D. On Mon, 12 Feb 2001 09:57:30 -0500 "David Tran" <[EMAIL PROTECTED]> writes: > Hi Everyone, > I need an answer rather quickly to this question. =20 > Which LSA type is NOT allowed in the Stub Area? > > A. Type 1, Route LSA > B. Type 2, Network LSA's=20 > C. Type 3, Secure LSA > D. Type 5, external LSA > > Many thanks > > David > [EMAIL PROTECTED] > > > > _ > FAQ, list archives, and subscription info: > http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to > [EMAIL PROTECTED] > GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Which LSA type is NOT allowed in the Stub Area?
Rather quickly? Why, do you have some homework due this morning? :-) Sorry, just kidding. I'm ornery when I haven't had any coffee. (disclaimer: I'm new to OSPF, please correct me if I'm wrong.) Every router advertises Type 1 LSAs, so it can't be A. Any DR in an area will advertise Type 2, so it can't be B. Type 3 LSAs are Summary, not Secure, so it's not C. Therefore, the answer is D. But why? The idea is that if this is a stub area (not to be confused with stub network), it only needs to receive routes about its own AS. The ABR to a stub area provides a default route for destinations outside of the AS. HTH, John > Hi Everyone, > I need an answer rather quickly to this question. =20 > Which LSA type is NOT allowed in the Stub Area? > > A. Type 1, Route LSA > B. Type 2, Network LSA's=20 > C. Type 3, Secure LSA > D. Type 5, external LSA > > Many thanks > > David > [EMAIL PROTECTED] > > > > _ > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Find the best deals on the web at AltaVista Shopping! http://www.shopping.altavista.com _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Which LSA type is NOT allowed in the Stub Area?
Well just remember what the purposes of Stub areas are. They are areas that don't need to have full routing information so they block all type 4 (ASBR Summary) and type 5 (external) LSAs from entering. One other thing. A Type 3 LSA is not referred to as a Secure LSA. It's a Network Summary LSA. At 09:57 AM 2/12/01 -0500, you wrote: >Hi Everyone, >I need an answer rather quickly to this question. =20 >Which LSA type is NOT allowed in the Stub Area? > >A. Type 1, Route LSA >B. Type 2, Network LSA's=20 >C. Type 3, Secure LSA >D. Type 5, external LSA > >Many thanks > >David >[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]
RE: Which LSA type is NOT allowed in the Stub Area?
D. -Original Message- From: David Tran [mailto:[EMAIL PROTECTED]] Sent: Monday, February 12, 2001 8:58 AM To: [EMAIL PROTECTED] Subject: Which LSA type is NOT allowed in the Stub Area? Hi Everyone, I need an answer rather quickly to this question. =20 Which LSA type is NOT allowed in the Stub Area? A. Type 1, Route LSA B. Type 2, Network LSA's=20 C. Type 3, Secure LSA D. Type 5, external LSA Many thanks David [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]
Which LSA type is NOT allowed in the Stub Area?
Hi Everyone, I need an answer rather quickly to this question. =20 Which LSA type is NOT allowed in the Stub Area? A. Type 1, Route LSA B. Type 2, Network LSA's=20 C. Type 3, Secure LSA D. Type 5, external LSA Many thanks David [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Need some guidance on OSPF Stub area, inverse mask and loopback
Daniel, With OSPF, if you can spare the addresses, loopbacks are always a good idea. 1) Stub areas do LSAs 1/2 internally, and do NOT get external routes (5) injected into them. ABR of the stub area will generate 3/4 for its area, stub or not. . 2) Good question! My guess is if the ASBR is just an ASBR, then it will not generate a 4 for itself; if it is an ABR, then it will generate a 4 for itself... I don't have my Thomas Thomas book to verify this, though. 3) that network statement 0.0.0.0 255.255.255.255...whew, look out free world... I wouldn't use it, personally! Your second choice is better; personally, I like to use network statements like so:network 1.1.1.1 0.0.0.0 area 11; when I look at my configs, I can see instantly who is participating in OSPF. HTH, Charles ""Daniel Boutet"" <[EMAIL PROTECTED]> wrote in message 8tc7g0$k4e$[EMAIL PROTECTED]">news:8tc7g0$k4e$[EMAIL PROTECTED]... > Please could anyone confirm these statements: > > 1) No AS External LSA (type 5) originate from a stub area > 2) No ASBR Summary LSA (type 4) originate from router > if not an ABR router (internal router) > 3) In the network statement you would use: > > router ospf 1 > network 0.0.0.0 255.255.255.255 area 10 > area 10 stub > > OSPF would run on all active interface (unless "passive-interface" > command used on some interface) > > Would you still use a loopback address? > > interface loopback0 > ip address 192.168.10.1 > router ospf 1 > network 0.0.0.0 255.255.255.255 area 10 > area 10 stub > > Wouldn't your "network statement" advertise (more LSA's) your loopback since > it "fit" > inside the all host address? Let's say you have 15 routers inside the stub > network (this is > a possibility, right?) would this produce > unnecessary LSA's by advertising the loopbacks? > Isn't the purpose of a stub area is to limit LSA? > > Or would you rewrite your network statement more restrictive: > > interface loopback0 > ip address 192.168.10.1 > router ospf 1 > network 192.168.100.1 0.0.63.255 area 10 (100+ allowed to be > advertised) > area 10 stub > > Am I understanding the concepts properly about the advertisement? > Is my wildcard ok in my last network statement? This is how I figure the > inverse mask: > > In short: 192.168. 0110 0100.1 (for readability only use third octet) >. 0011 . (I matched the 0 bit for the "I > care" >and the 1 bit for > the "Don't care" > Thanks > > Daniel > > > > _ > 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]
Need some guidance on OSPF Stub area, inverse mask and loopback
Please could anyone confirm these statements: 1) No AS External LSA (type 5) originate from a stub area 2) No ASBR Summary LSA (type 4) originate from router if not an ABR router (internal router) 3) In the network statement you would use: router ospf 1 network 0.0.0.0 255.255.255.255 area 10 area 10 stub OSPF would run on all active interface (unless "passive-interface" command used on some interface) Would you still use a loopback address? interface loopback0 ip address 192.168.10.1 router ospf 1 network 0.0.0.0 255.255.255.255 area 10 area 10 stub Wouldn't your "network statement" advertise (more LSA's) your loopback since it "fit" inside the all host address? Let's say you have 15 routers inside the stub network (this is a possibility, right?) would this produce unnecessary LSA's by advertising the loopbacks? Isn't the purpose of a stub area is to limit LSA? Or would you rewrite your network statement more restrictive: interface loopback0 ip address 192.168.10.1 router ospf 1 network 192.168.100.1 0.0.63.255 area 10 (100+ allowed to be advertised) area 10 stub Am I understanding the concepts properly about the advertisement? Is my wildcard ok in my last network statement? This is how I figure the inverse mask: In short: 192.168. 0110 0100.1 (for readability only use third octet) . 0011 . (I matched the 0 bit for the "I care" and the 1 bit for the "Don't care" Thanks Daniel _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Stub Area
Please could anyone confirm these statements: 1) No AS External LSA (type 5) originate from a stub area 2) No ASBR Summary LSA (type 4) originate from router if not an ABR router (internal router) 3) In the network statement you would use: router ospf 1 network 0.0.0.0 255.255.255.255 area 10 OSPF would run on all active interface (unless "passive-interface command" used on some interface)) Would you still use a loopback address? interface loopback0 ip address 192.168.10.1 router ospf 1 network 192.168.100.0 0.0.255.255 area 10 Wouldn't your "network statement" advertise your loopback since it "fit" inside the inverse mask or would you write your network statement more restrictive: router ospf 1 network 192.168.100.0 0.0.0.255 area 10 Let's say you have 15 routers inside the stub network; would this produce uneccessary LSA's? I am still learning the OSPF process so please be very descriptive in your answer. Thanks Daniel _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF question- stub area
Brian, I'm not sure on the exact details but I do know because I've tried this... If you don't configure all routers in the stub area to tell them they are all in a stub area they will not establish adjacancies with each other. Because some will think they are stub and some not.So to put it simply... No worky. Cory -Original Message- From: Field, Brian [mailto:[EMAIL PROTECTED]] Sent: Thursday, May 11, 2000 4:51 AM To: Thomas Trygar Cc: [EMAIL PROTECTED] Subject: RE: OSPF question- stub area Thomas, Thanks for the response. I'm still unclear as to why an area internal router needs to know that it is in a stub area. If the ABRs are tagged with the stub indicator and are filtering type 5 LSAs from being advertised into the area, why would an internal router need to be configured to know this? Suppose we were to remove the stub flag from the Hello protocol. All routers in a stub area would then negotitate the two-way state and evetually have the same link database. How would the lack of a router knowing it was in a stub area impact OSPF operation on the router? For a Totally stubby area, the internal routers are not aware that they're in a TSA and won't be receiving type 3/4 LSAs. So why must an internal stub router know that it is in a stub? Thanks Brian -Original Message- From: Thomas Trygar [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 10, 2000 9:08 PM To: Field, Brian Cc: [EMAIL PROTECTED] Subject: Re: OSPF question- stub area Brain, All routers within a stub area must have identical Link State Databases. "Field, Brian" wrote: > When configuring a stub area, why is it that all routers > in the stub area must be tagged as being in a stub? > > Ok, so the Hello mechanism requires that adjacent routers > agree that they are in the same area and both have been > configured as being in a stub area. > > Besides the Hello negotiation, what is the reason for requiring > this? Why is it not sufficient to tag the stub area ABRs as > being stubs and be done with it (much like is done with the > "no-summary" tag being required only in ABRs to a totally > stubby area)? > > Thanks > Brian > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF question- stub area
I broke down and refered to RFC 2138 to see if there
was a description as to why all routers in a stub
area must be configured as stubs. In section 3.6,
there is a two sentence paragraph which provides
a bit of information:
The OSPF protocol ensures that all routers belonging to an area agree
on whether the area has been configured as a stub. This guarantees
that no confusion will arise in the flooding of AS-external-LSAs.
So, the reason for tagging each stub router as being
in the stub is to make sure there is no confusion regarding
the flooding of AS-external LSAs. The Hello protocol does
this enforcement. If a type 5 LSA was to somehow magically
appear in the stub area, each router would know not to flood
it. Ok, I buy that.
Now, the ABRs are going to be the ones that flood AS-external
LSAs into the stub area. It should be sufficient to tag only
the ABRs as stubs (much like only the ABRs are "no-summary"
tagged for Totally stubby areas) to prevent these type 5 LSAs
from getting into the stub. But I'd buy the argument that by
configuring all area stub routers as being stubs will help detect
misconfiguration of an stub ABR.
If the reason is to maintain consistency, then why is
the no-summary not also applied to all internal stub
routers when they're in a Totally stub area?
Not at peace yet...
Brian
-Original Message-
From: Thomas Trygar [mailto:[EMAIL PROTECTED]]
Sent: Thursday, May 11, 2000 6:16 AM
To: Field, Brian
Cc: [EMAIL PROTECTED]
Subject: Re: OSPF question- stub area
Brian,
That's the way they made it. Accept it and be at peace.
The ABR will inject a default route X.X.X.X 0.0.0.0 X.X.X.X into area for
other
stub areas. This is so stub area routers know that for anything they don't
know,
go here (second X.X.X.X).
All area routers' Link State Databases must match.
The Hello packet E-bit ('stub area' option bit) must be correct on all area
routers since entire Hello Packet must match for adjacencies to form.
Tom Trygar
"Field, Brian" wrote:
> Thomas,
>
> Thanks for the response.
>
> I'm still unclear as to why an area internal router needs
> to know that it is in a stub area. If the ABRs are tagged
> with the stub indicator and are filtering type 5 LSAs from
> being advertised into the area, why would an internal router
> need to be configured to know this?
>
> Suppose we were to remove the stub flag from the Hello protocol.
> All routers in a stub area would then negotitate the two-way
> state and evetually have the same link database.
>
> How would the lack of a router knowing it was in a stub
> area impact OSPF operation on the router? For a Totally
> stubby area, the internal routers are not aware that they're
> in a TSA and won't be receiving type 3/4 LSAs. So why
> must an internal stub router know that it is in a stub?
>
> Thanks
> Brian
>
> -Original Message-
> From: Thomas Trygar [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, May 10, 2000 9:08 PM
> To: Field, Brian
> Cc: [EMAIL PROTECTED]
> Subject: Re: OSPF question- stub area
>
> Brain,
>
> All routers within a stub area must have identical Link State Databases.
>
> "Field, Brian" wrote:
>
> > When configuring a stub area, why is it that all routers
> > in the stub area must be tagged as being in a stub?
> >
> > Ok, so the Hello mechanism requires that adjacent routers
> > agree that they are in the same area and both have been
> > configured as being in a stub area.
> >
> > Besides the Hello negotiation, what is the reason for requiring
> > this? Why is it not sufficient to tag the stub area ABRs as
> > being stubs and be done with it (much like is done with the
> > "no-summary" tag being required only in ABRs to a totally
> > stubby area)?
> >
> > Thanks
> > Brian
> >
> > ___
> > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html
> > FAQ, list archives, and subscription info: http://www.groupstudy.com
> > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
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Re: OSPF question- stub area
Brian,
That's the way they made it. Accept it and be at peace.
The ABR will inject a default route X.X.X.X 0.0.0.0 X.X.X.X into area for other
stub areas. This is so stub area routers know that for anything they don't know,
go here (second X.X.X.X).
All area routers' Link State Databases must match.
The Hello packet E-bit ('stub area' option bit) must be correct on all area
routers since entire Hello Packet must match for adjacencies to form.
Tom Trygar
"Field, Brian" wrote:
> Thomas,
>
> Thanks for the response.
>
> I'm still unclear as to why an area internal router needs
> to know that it is in a stub area. If the ABRs are tagged
> with the stub indicator and are filtering type 5 LSAs from
> being advertised into the area, why would an internal router
> need to be configured to know this?
>
> Suppose we were to remove the stub flag from the Hello protocol.
> All routers in a stub area would then negotitate the two-way
> state and evetually have the same link database.
>
> How would the lack of a router knowing it was in a stub
> area impact OSPF operation on the router? For a Totally
> stubby area, the internal routers are not aware that they're
> in a TSA and won't be receiving type 3/4 LSAs. So why
> must an internal stub router know that it is in a stub?
>
> Thanks
> Brian
>
> -Original Message-
> From: Thomas Trygar [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, May 10, 2000 9:08 PM
> To: Field, Brian
> Cc: [EMAIL PROTECTED]
> Subject: Re: OSPF question- stub area
>
> Brain,
>
> All routers within a stub area must have identical Link State Databases.
>
> "Field, Brian" wrote:
>
> > When configuring a stub area, why is it that all routers
> > in the stub area must be tagged as being in a stub?
> >
> > Ok, so the Hello mechanism requires that adjacent routers
> > agree that they are in the same area and both have been
> > configured as being in a stub area.
> >
> > Besides the Hello negotiation, what is the reason for requiring
> > this? Why is it not sufficient to tag the stub area ABRs as
> > being stubs and be done with it (much like is done with the
> > "no-summary" tag being required only in ABRs to a totally
> > stubby area)?
> >
> > Thanks
> > Brian
> >
> > ___
> > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html
> > FAQ, list archives, and subscription info: http://www.groupstudy.com
> > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
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RE: OSPF question- stub area
Thomas, Thanks for the response. I'm still unclear as to why an area internal router needs to know that it is in a stub area. If the ABRs are tagged with the stub indicator and are filtering type 5 LSAs from being advertised into the area, why would an internal router need to be configured to know this? Suppose we were to remove the stub flag from the Hello protocol. All routers in a stub area would then negotitate the two-way state and evetually have the same link database. How would the lack of a router knowing it was in a stub area impact OSPF operation on the router? For a Totally stubby area, the internal routers are not aware that they're in a TSA and won't be receiving type 3/4 LSAs. So why must an internal stub router know that it is in a stub? Thanks Brian -Original Message- From: Thomas Trygar [mailto:[EMAIL PROTECTED]] Sent: Wednesday, May 10, 2000 9:08 PM To: Field, Brian Cc: [EMAIL PROTECTED] Subject: Re: OSPF question- stub area Brain, All routers within a stub area must have identical Link State Databases. "Field, Brian" wrote: > When configuring a stub area, why is it that all routers > in the stub area must be tagged as being in a stub? > > Ok, so the Hello mechanism requires that adjacent routers > agree that they are in the same area and both have been > configured as being in a stub area. > > Besides the Hello negotiation, what is the reason for requiring > this? Why is it not sufficient to tag the stub area ABRs as > being stubs and be done with it (much like is done with the > "no-summary" tag being required only in ABRs to a totally > stubby area)? > > Thanks > Brian > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF question- stub area
Brain, All routers within a stub area must have identical Link State Databases. "Field, Brian" wrote: > When configuring a stub area, why is it that all routers > in the stub area must be tagged as being in a stub? > > Ok, so the Hello mechanism requires that adjacent routers > agree that they are in the same area and both have been > configured as being in a stub area. > > Besides the Hello negotiation, what is the reason for requiring > this? Why is it not sufficient to tag the stub area ABRs as > being stubs and be done with it (much like is done with the > "no-summary" tag being required only in ABRs to a totally > stubby area)? > > Thanks > Brian > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
OSPF question- stub area
When configuring a stub area, why is it that all routers in the stub area must be tagged as being in a stub? Ok, so the Hello mechanism requires that adjacent routers agree that they are in the same area and both have been configured as being in a stub area. Besides the Hello negotiation, what is the reason for requiring this? Why is it not sufficient to tag the stub area ABRs as being stubs and be done with it (much like is done with the "no-summary" tag being required only in ABRs to a totally stubby area)? Thanks Brian ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
