After advertised DMVPN IP on EIGRP, EIGRP Network is flapping.

edited June 2017 in Foundation Lab 1

Hi, Everyone.

Re: 6.2 - EIGRP over DMVPN

After DMVPN on Foundation LAB 1 I advertise Tunnel 0 IP in EIGRP and my network is flapping.

"Midchain parent maintenance for IP midchain out of Tunnel0, addr 10.1.0.5 looped chain attempting to stack"

When I read about this it's happen coz of tunnel recursion. I think I feel it's coz of loopback 0 is redistributed problem (1. lo 0 redist into EIGRP , 2. lo 0 redist into EBGP)

Any clue how to solve that error? If i move tunnel 0 ip in EIGRP my tunnel is fine.

With Best Regard,

Comments

  • tunnel recursion could happen if you are using same routing protocol for underlay & overlay if so then you need to filter tunnel source from being advertised inside the tunnel.
    you could filter the source in many ways like prefix lis

    ip prefix-list filter_loop deny 10.10.10.10/32
    ip prefix-list filter_loop deny 10.10.10.10/32
    router eigrp 100
    distribute-list prefix filter_loop out tunnel 0

  • @ raedalya
    I can't apply such solution here is error

    distribute-list prefix LOOP out tunnel 0

    % Interface not allowed with OUT in case of OSPF

    Now what would be the solution? Do I run different protocol. Please note Static route also don't work.....

  • It's not tunnel recursion, check the routing table. You'll notice once you bring up eigrp the loopback 0 addresses are being learnt by ebgp and then external eigrp, this wasn't noticed before bringing eigrp over dmvpn up, as the loopbacks from R1, R5, R6, R9 were learnt via ebgp. I'm not telling you how to fix it, lab it up again

  • JoeMJoeM ✭✭✭

    Hello write_mem.
    It sounds like you are saying the same thing. It is recursive routing. This is a common gotcha with DMVPN. **Recognizing this error will save a lot of time when doing the lab exam. **

    It is a result of the tunnel end-points being learned over the tunnel. These tunnel destinations should only be learned via the underlay protocol.

    I am sure that there were other errors/symptoms that the poster left out -- like tunnel flapping.

    ****There are different ways to fix this, depending on the situation. ****

    • Being sure not to advertise the local end-point over the tunnels(s)
    • Filtering incoming routes on the tunnel.
    • Using Front-End VRFs.
    • Filtering any redistribution between the underlay and overlay protocols.
      .
      .

    I'm not telling you how to fix it, lab it up again

    Huh? That is what this forum is for, right? Candidates helping each other.

Sign In or Register to comment.