See feedback inline. Eric
----- Original Message ----- From: "The Long and Winding Road" To: Sent: Thursday, March 27, 2003 7:09 AM Subject: OSPF Tricks of the Trade [7:66308] > After wrestling with Solie this afternoon, it suddenly occurred to me that > there is a typical instruction in the various practice labs that can end up > driving you nuts if you look at it from one direction, but which is really > simple if looked at from another. > > The topology: several routers over frame relay. Usually four routers. One > acts as hub, The others as spokes. > > the instruction: you must use subinterfaces only on the hub. On the spokes > you MUST use the physical interfaces. two of the spoke routes connect to the > hub via one subinterface. The other router connects to the hub on the other > subinterface. > > the catch: some bizarre restriction or other about network types, commands > that can or cannot be used, the usual BS. > > It occurs to me that working backwards, you can solve most problems, > whatever the restrictions and twists. > > Frame relay: OSPF default > ----------------- -------------------- > > physical interface non broadcast > > subinterface - p2p point-to-point > > subinterface - multipoint non broadcast > > I think the knee jerk reaction is to create a multipoint subinterface for > the link to the two spoke routers, and a p2p subinterface for the link to > the single spoke router. Then moan in despair as you realize that the > instructions forbid the use of any ip ospf network commands anywhere. > > But if you look from the higher level viewpoint, you see that the physical > and the multipoint subinterface default to the same type of OSPF network. > Life is easier after that. Yes, that's the first thing I do: determine the default OSPF network type of involved interfaces After that investigate what this means for: - hello and dead timers (are they equal yes/no?); - DR/BDR election (yes/no); if yes: manual configuration required (by means of priority in neighbor statement), or is it automatic? - manual neighbor configuration required (yes/no)? > > Is this making sense? I'm at the end of a very long day, with too many > subtleties floating around in what's left of my brain. > > Good night, everyone. > > > > > > > > -- > TANSTAAFL > "there ain't no such thing as a free lunch" Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=71302&t=66308 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
