Hi Fulvio, I think your confusion comes from the usual split-horizon definition that "a route is never advertised out an interface it is learned from," but that's an incomplete definition. Split-horizon comes into play when the *best* route is learned from an interface, in which case it will not be sent back out that same interface. Since R1 & R2 in your example would each have their best path (successor route) through their "other" interface, they would both advertise a path onto the common segment for R1-4. R3 & R4 would learn equal-cost routes via both 1 & 2.
Hope that helps, Bob Sent from my iPad On Aug 9, 2012, at 10:55 AM, Fulvio allegretti <[email protected]> wrote: > Right, I know the best thing to do here would be to lab this and I will, > promise, but I'd like to know your understanding on this and if it is > something to worry about. > Let's say we have 4 routers on a LAN all talking eigrp. Two of these routers, > router 1 and 2, have an eigrp path to subnet 1.1.1.0/24 somewhere else > thorugh an interface not on the LAN and lets's assume for sake of argument > that the metric to 1.1.1.0/24 is the same for both of them. Considering > split-horizon there will be only one router, 1 or 2, injecting that route on > the LAN, right? One of the two routers will have its best path to 1.1.1.0/24 > through its own interface but won't inject it on the lan as it heard it > injected on the LAN from the other one. > 1) What decides which one of the two will inject the route on LAN? Is it the > first router timewise that injects it on the LAN? > 2) Let's assume R1 did, what happens if the metric through R2 "improves", > would the LAN routers choose the path through R2 now? > Fulvio > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > Are you a CCNP or CCIE and looking for a job? Check out > www.PlatinumPlacement.com > > http://onlinestudylist.com/mailman/listinfo/ccie_rs _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
