I haven't seen any feedback from others on your thoughts. See my comments below.
Eric ----- Original Message ----- From: "The Long and Winding Road" To: Sent: Sunday, March 16, 2003 8:13 AM Subject: OSPF Topology Question - Parkhurst's Book [7:65532] > Ran into something in Parkhurst's OSPF book while studying tonight. Looking > for validation of my observation. > > The example: OSPF over frame relay > > The topology: hub and spoke, with a twist. The hub uses subinterfaces ( one > to each spoke router ) and the spokes use physical interfaces. > > Now, the Parkhurst examples show leaving the physical interfaces as ospf > type non-broadcast, change the ospf timers on the subinterfaces, place > neighbor statements on the spoke routers ( physical interfaces ) and all is > well. > > Except I don't believe it works this way. Neither do I, but I'm not sure. I wouldn't configure it like this. The spoke routers ( physical interfaces ) try to elect DR/BDR, which is not applicable for point-to-point interface on hub router. Note: if it were IS-IS, it would fail, since network types must match. > > The subinterfaces are point-to-point networks, and expect the other side to > be a point-to-point connection and adjacency. the physical interfaces are > non-broadcast, and expect DR elections to occur, something the router with > the subinterfaces will not do. Yep. > > I believe the correct solution is to make the physical interfaces ospf type > point-to-multipoint. If hub is p2p and spokes are p2m, then: - neither side requires DR/BDR election, which is good; - no manual neighbor configuration needed, which is good as well; - hello/dead timer are different (10/40 vs. 30/120 s), so you need to change one side, don't you? This should work. > > An alternative is to change the physical interfaces to ospf point-to-point. > Yes. > In any case - can anyone else verify what I see and do not see - that > Parkhurst chapter 11, example 3, pages 275-279 answer is incomplete? > I don't have that book. My still-to-read-pile is already too big. > thanks. > > -- > TANSTAAFL > "there ain't no such thing as a free lunch" Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=71301&t=65532 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
