Thanks for the reply! Good point about the router ID. After the first response, I began playing with the OSPF "router-id" command, and subsequently discovered that the virtual-link must be defined as terminating at the router-id, and not the physical interface or in any specific area. As far as joining discontiguous nonzero areas, I would be interested to see the configs...
-Jeremy -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Chuck Sent: Thursday, April 25, 2002 6:29 PM To: [EMAIL PROTECTED] Subject: Re: OSPF Virtual-links [7:42565] In the world of OSPF, the virtual link end points are the router RID's This is defined in the RFC. with virtual links, the hello packet has the V bit set to 1. I believe that the TTL of the IP packet transporting the VL hello is set to 255. In any case, virtual link hellos are forwarded until such time as they reach a router who meets the VL end point requirement or until they reach the end of the area over which the virtual link is to travel. I presume that virtual link packets do not wander aimlessly through an OSPF domain, but stop at the border of the defined transit area. So, in answer to your question, no, the termination point of the virtual link does not have to be an interface in area 0. in fact, virtual links can be used to join discontiguous non zero areas. There is an example of this in Terry Slattery's book Advanced IP Routing in Cisco Networks. HTH ""Jeremy"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > My question is regarding OSPF and virtual links. As you can see, I have > created an area 23 between R2 and R3 such that R3 will need a virtual link > defined in order to have a connection to Area 0. My question is, does R3 > have to peer with an interface in R2 that is a member of area 0? I have > noticed that if I put R2's loopback interface (which R3 is peering to) in > area 23, it fails, whereas, if I move the interface to area 0, the virtual > link comes up. Please take a look at the crude diagram below, or the > attached visio for clarification. Please let me know your thoughts on this. > Thanks again for all of your informed help (and I apologize if this appears > to be a less-than-CCIE-caliber question). > > Topology map (excuse the crude map, if you have visio, check out the > enclosed diagram: > R5---R1 > / \ > / \ > R4 R2--R3 > > Router2: > router ospf 10 > area 23 virtual-link 130.10.23.3 > network 130.10.2.2 0.0.0.0 area 0 (Loopback Interface) > network 130.10.23.2 0.0.0.0 area 23 (Link to R3 Serial Interface (S1)) > network 130.10.245.2 0.0.0.0 area 0 (Link to R5 Frame-Relay Interface (S0) > [DR=R5]) > > Router3: > router ospf 10 > area 23 virtual-link 130.10.2.2 (Virtual link peering to Loopback on R2 (in > area 0, does it have to be?) > network 130.10.23.3 0.0.0.0 area 23 (link to R3 Serial Interface (S0)) > > Router4: > router ospf 10 > network 130.10.4.4 0.0.0.0 area 4 (Loopback Interface) > network 130.10.245.4 0.0.0.0 area 0 (Link to R5 Frame-Relay Interface (S0) > [DR=R5]) > > Router5: > router ospf 10 > network 130.10.5.5 0.0.0.0 area 5 > network 130.10.245.5 0.0.0.0 area 0 > neighbor 130.10.245.2 > neighbor 130.10.245.4 > > > BTW, anyone else taking the exam on April 30th? I am...heheh... > > [GroupStudy.com removed an attachment of type application/vnd] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=42657&t=42565 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
