EIGRP not Load balancing

[n-ranganathan]

Hi ,

Iam facing issue  with EIGRP not load balancing . Just to give  you all a  quick  background

.  The branch had two ASR  routers. One of the ASR router( router 1) is  connected to  a Hub router (  let me call  it Hub 1) and another ASR router(router 2) was connected to hub 2 Router

 Recently we  replaced  Hub 2  router as well as  branch  router 2  with 4500x  switch   at  both the end.

  After we  made this  changes  we  see  the EIGRP is not getting load balanced.   We checked from the Distribution L3 switch  by running   sh ip route 0.0.0.0      we see the route is learned  only via the  Router1/hub1  segment  and  it is not learning through the second leg(  Router2/hub2) after we replaced the routers with 4500x.

Kindly note the 

1. In all the segments EIGRP is up and  we can see EIGRP neighborship formed.
2. We have injected  ip summary-address eigrp 109 0.0.0.0 0.0.0.0   injected in both the hub end
3. The Router1/hub1 has IPsec tunnel b/w the branch and the hub end.
4. However in the  Router2/hub2  there is no IPsec tunnel as we have replaced the boxes with 4500x.

I  want to know why there is a  why there is a different behavior using ‘ip summary-address’ command between ASR1004 and 4500x boxes.

 secondly  is the EIGRP not load balancing because  one leg has  ASR  routers  with IPsec  tunnel in which EIGRP is riding over it  and another  leg has  4500x .

You expert suggestion is appreciated.

[Richard Burts]

We do not know enough of the detail to be able to say exactly what it is, but clearly when your environment was two ASR routers then the EIGRP metrics advertised were exactly the same and EIGRP load balanced. And clearly when you changed from an ASR to 4500 something changed and the EIGRP metrics advertised are not the same. Perhaps it is the difference of not having the IPsec, or perhaps it is that the switch interfaces have a different bandwidth than the ASR did.

HTH

Rick

[n-ranganathan]

Hi Rick,

  Thanks for the reply and which helped me to look in the right direction.  Infact  I checked further  and found there is a difference  in bandwidth  b/w  both the legs of the link.  The 4500x has different bandwidth than that of ASR routers which is causing all the traffic flow only through the  ASR routers.

when I did   sh ip route 0.0.0.0 0.0.0.0  from 4500x  box itself , instead of learning the routes  through directly connected WAN link , it is learning through LAN segment.

Does on Leg  having IPsec and another not having IPsec  makes any difference.

Thanks again for helping me to go in right direction.

[Richard Burts]

I am glad that my suggestion pointed you in the right direction. Having IPsec or not having IPsec would not make a difference if EIGRP is running on the physical interface but could make a difference if EIGRP is running through the IPsec.

HTH

Rick