EIGRP routing loop question

chapapachapapa Posts: 40Member ■■□□□□□□□□
We all know that in order for a route to be a FS in eigrp, the RD must be less than the FD.

My issue here is that what if my RD is greater than my FD, therefore it is not an FS, then how does the routing loop occurs in the network?

I'm trying to understand WHY the rule RD < FD ensure loop-free routing, I can't get the concept of how that loop happens.

anyone would take this case? thank you!

Comments

  • JackaceJackace Posts: 335Member
    EIGRP Feasible Successor Routes - Packet Life

    There is a section in there at the end which explains this very topic and gives an example.
  • chapapachapapa Posts: 40Member ■■□□□□□□□□
    Jackace wrote: »
    EIGRP Feasible Successor Routes - Packet Life

    There is a section in there at the end which explains this very topic and gives an example.

    I've read this article earlier and try labbing it, and can't find where the loop is. I tried to shutdown the interface connecting R1 to R3, but the route just shift from the R2 -- R3 -- R5 which for seems all is working. what I'am missing? I tried to follow the route of the loopback I added on R5 to look for the loop
  • JackaceJackace Posts: 335Member
    chapapa wrote: »
    I've read this article earlier and try labbing it, and can't find where the loop is. I tried to shutdown the interface connecting R1 to R3, but the route just shift from the R2 -- R3 -- R5 which for seems all is working. what I'am missing? I tried to follow the route of the loopback I added on R5 to look for the loop

    You are not going to find the loop in his example because EIGRP stops the loop from happening. What he is telling you in that last part about the loop prevention is if EIGRP didn't have that mechanism this topology could cause a loop.
  • chapapachapapa Posts: 40Member ■■□□□□□□□□
    Jackace wrote: »
    You are not going to find the loop in his example because EIGRP stops the loop from happening. What he is telling you in that last part about the loop prevention is if EIGRP didn't have that mechanism this topology could cause a loop.

    I see. thanks for the info! :)
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