Redundant WAN iBGP with dual EIGRP processes

Unanswered Question
May 14th, 2007

I have a situation where I am looking for a routing guru to help - it would be greatly appreciated!!

My company has several sites that communicate via MPLS lines over DS3 circuits. These are private IP services so only iBGP is utilized.

We recently started an initiative to provide full redundancy to our sites using backup MPLS DS3 circuits and to configure seamless failover so that if the primary DS3 MPLS goes down, the backup takes over and there is little to no indication to the end user.

The first problem isn't so hard to solve.. we just use the loopback interfaces with iBGP and use prepend as-path to tag traffic for the primary interface with a higher priority.. see http://www.dslreports.com/faq/14664 for a good example - our config is very close to this.

So within our network we are running EIGRP which redistributes into iBGP. Because of certain networking and security requirements, we have to have several static routes. We deal with this now by redistributing static and connected into EIGRP and subsequently into BGP.

The problem we are running into, is that when we tried to apply these configurations we kept getting routing loops. What happens is that one router (let's call it RouterA_WAN) advertises it's static route.. that route gets advertised via EIGRP to RouterB_WAN.. which then turns right around and advertises it back and WHAM!! routing loop.

We cannot take out these redistributions without serious detriment and a huge mess of static routes everywhere... so we are trying to find a way to deal with this situation..

One theory is that we use two EIGRP processes, though Cisco doesn't recommend that..

Another theory is to use OSPF and redistribute that with EIGRP (though the cost would be higher and it wouldn't create a loop) but this would increase the overhead quite a bit.

Anyone have any good ideas as to which direction to take this??

Thank you in advance!!

I have this problem too.
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mohammedmahmoud Mon, 05/14/2007 - 12:33

hi,

Where is the part describing the 2 EIGRP processes, how are they running ?

BR,

Mohammed Mahmoud.

mohammedmahmoud Mon, 05/14/2007 - 12:40

Hi,

Most probably this is a mutual redistribution problem, try doing the redistribution using route-maps as follows:

!

route-map eigrp-to-bgp deny 10

match tag 13

!

route-map eigrp-to-bgp permit 20

set community 65002:13 additive

!

route-map bgp-to-eigrp deny 10

match community 13

!

route-map bgp-to-eigrp permit 20

set tag 13

ip community-list 1 permit 65002:13

HTH, please do rate all helpful replies,

Mohammed Mahmoud.

sct0321 Mon, 05/14/2007 - 12:42

ip community-list 1 permit 65002:13 <- what is :13 ?

mohammedmahmoud Mon, 05/14/2007 - 12:45

Hi,

"65002:13" is an example for a community number in aa:nn format.

Where aa = your ASN and nn is a random number.

HTH, please do rate all helpful replies,

Mohammed Mahmoud.

sct0321 Mon, 05/14/2007 - 12:36

I'm having the same issue with my WAN duel providers and IBGP / EIGRP. Looping and redist of EIGRP.

Scott

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