Bob, Sorry for my Extreme utterance, not meant to be literal.
Joe Sanchez From: Bob McCouch <[email protected]> Date: Fri, 10 Aug 2012 14:08:42 -0400 To: Joe Sanchez <[email protected]> Cc: Fulvio allegretti <[email protected]>, "[email protected]" <[email protected]> Subject: Re: [OSL | CCIE_RS] EIGRP in broadcast environment Please elaborate. DUAL should ensure a loop-free topology by selecting the lowest metric path for each of R1 and R2. The path heard by the other router would be installed in the topology table, possibly as a feasible successor if the route metric is appropriate. Can you explain how the loop forms? Bob -- Sent from my iPhone, please excuse any typos. On Aug 10, 2012, at 2:00 PM, Joe Sanchez <[email protected]> wrote: > I see a loop.. > > On Fri, Aug 10, 2012 at 8:20 AM, Bob McCouch <[email protected]> wrote: >> 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 >>> <http://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 >>> <http://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 >>> <http://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 <http://www.ipexpert.com> >>> > >>> > Are you a CCNP or CCIE and looking for a job? Check out >>> www.PlatinumPlacement.com <http://www.PlatinumPlacement.com> >>> > >>> > http://onlinestudylist.com/mailman/listinfo/ccie_rs >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, please >> visit www.ipexpert.com <http://www.ipexpert.com> >> >> Are you a CCNP or CCIE and looking for a job? Check out >> www.PlatinumPlacement.com <http://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
