EIGRP protocol behaviour for routes in passive state

[neil_titchener]

Hi All,

I have four routers in the same BGP AS which redistribute their BGP routes into EIGRP. There are route-maps to prefer one router over another for particular subnets and that all works fine when the routers are turned on in the right order. However over time our ISP seems to loose BGP connections to remote sites and when they re-establish the connection the route can appear in EIGRP pointing to any of the four routers, not the one with the best metric. My question is once EIGRP is in a passive state for a route if the same route is offered with a better metric through redistribution should EIGRP accept that route or does it ignore the new route as it's in a passive state for that particular destination? The setup is a little complicated but it's been reviewed by a CCIE and he believes the configuration is correct. Also when creating a similar setup in the lab and running failover tests it all appears to work fine so in this question I'm really after information on how EIGRP should behave in this scenario as I can't find any information on line although I'm sure it's there somewhere, I just can't find it :-)

Thanks in advance.

[mkazam001]

you may find this attachment useful - it explains EIGRP SIA.

regards, mk

[neil_titchener]

Thanks for the response MK but this issue is around redistribution from BGP into EIGRP.  I have read through the document you provided but I don't see any cross-over here.

thanks again.

[Richard Burts · Accepted solution]

Perhaps there are things in your environment or in your question that I do not understand correctly but it seems to me that the answer is pretty straight forward. When EIGRP is in passive state for a route it means that EIGRP will keep the entry in the table and not actively search for a replacement. EIGRP does pay attention to updates from neighbors. If a neighbor sends an advertisement for the route with a more attractive metric then EIGRP will replace the entry. 

Remember that passive does not mean permanent. It only means do not actively search. If a better entry is presented then the better entry will be used. 

HTH

Rick

[neil_titchener]

Thank s for the reply Rich, that was as what I thought.  I won't go into detail because the setup is a little complicated but based on your answer I will now raise a ticket with Cisco.

thanks again.

[Richard Burts]

I am glad that my explanation was helpful. I am not clear what your issue is. But for the question about the behavior of EIGRP in passive state I am clear about that behavior. I hope that the ticket with Cisco will clear up the issue. Thank you for marking the question as solved. This will help other participants in the community to identify discussions which have helpful information. 

HTH

Rick