now I'm gonna have to set up a test - seeing if a virtual link will indeed join two non-backbone areas. Funny, the issue has never come up in any of the study materials or various test lab scenarios that I have seen.
although to be truthful, if the transit area is the backbone, I'm not sure what kind of havoc this might create. I'll check the thread started by Aussie Jenny a couple of days ago. That might prove to be a good source for the scenario. I'll set something up later this week and report back. Chuck ""Howard C. Berkowitz"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > >I don't recall the entire context of this particular discussion, but there > >is an error in the commentary below that I wanted to correct. > > > >>Unfortunately, the RFC only addresses virtual links as a means to repair > >> a partitioned backbone. It does not address providing bacbone > >> connectivity to a non-backbone area. Nor does the RFC discuss demand > >circuits, which, > >> of course, is a Cisco implementation. So there may very well be a > >> "gottcha" in there that simply isn't addressed in the "official" OSPF > >documentation. > > First, I wondered about this, and asked John Moy, editor and primary > author of the OSPF specification. John is generally considered the > inventor of virtual links. > > He told me that his original concept was to provide backbone > connectivity to a non-backbone area; the backbone restoral > application came later. > > I can't remember if this was in his first book, "OSPF: Anatomy of an > Internet Routing Protocol," for which I was a technical reviewer. It > may be. He certainly discusses there some of the original ideas that > were never implemented widely or at all, because people found a > better way (e.g., pervasive iBGP rather than BGP-OSPF interaction and > database overflow). > > Second, the current specification (RFC 2328) contains both virtual > links and demand circuits. > > > > >RFC 1753 does indeed address OSPF demand circuits. They are not a "Cisco > >implimentation" > > > >A virtual link is a kind of demand circuit, and is described in RFC 1753 as > >well. > > > >Us router jocks sometimes can forget that the folks who designed the > >standards put a lot of thought into the process. If something wasn't > >covered, or something came up subsequent to the original standard, it tends > >to get addressed later. > > > There's some truth to this here, because the original specification > for virtual links in OSPF version 1 was buggy. The bugs were fixed > in version 2, the current version. > > >Chuck Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40748&t=34379 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
