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Community Member

BGP / EIGRP Interaction Issue

Hi all,

We have multiple regional exit points to an external services network, ie access to company A network via a link in NY and a link in London and at both sites we have mutul redistribution. Both sites connect into a BGP MPLS core network.

Basically (lets say in NY), if we have an overlapping network, ie 1.1.1.0/24 coming in from eBGP originated from London and the local site (NY) IGP (say eigrp), the eigrp route gets to the NY CE BGP/routing table first as you would expect, all is fine. If this route flaps for some reason out in the IGP cloud, the CE router will lose the eigrp route and install the eBGP route in its table. After this has happened the IGP route is again available, but the EIGRP route WILL NEVER get into the CEs RT and override a route with an AD of 20 (unless you do a clear ip route <prefix>)

Is the following the way to fix this? Or is there anything else I should be looking at?

http://www.cisco.com/application/pdf/en/us/guest/tech/tk207/c1482/cdccont_0900aecd801e4a6b.pdf

Also, what about OSPF and BGP Interaction, I assume this would be the same?

Many thx indeed,

Ken

2 REPLIES

Re: BGP / EIGRP Interaction Issue

How about network 1.1.1.0 backdoor on the BGP? That would install the eBGP route with an AD of 200 so that it can be overwritten by your IGP.

http://www.cisco.com/en/US/products/ps6350/products_command_reference_chapter09186a0080454cee.html#wp1074098

Kevin Dorrell

Luxembourg

Community Member

Re: BGP / EIGRP Interaction Issue

many thx. yes, that is one of the considerations we have, or manipulating AD.

Thing is, is this quite common, say for overlapping networks (ie in IGP and received from BGP?)

Many thx mate

Ken

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