Eigrp flapping

Unanswered Question
Sep 6th, 2007
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Hi,


We are using eigrp and have problems with routing protocol flapping:


*Sep 6 16:15:36.379 CEST: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 172.16.0.1 (Tunnel1) is up: new adjacency

*Sep 6 16:16:20.079 CEST: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 172.16.0.1 (Tunnel1) is down: holding time expired

*Sep 6 16:16:29.483 CEST: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 172.16.0.1 (Tunnel1) is up: new adjacency

*Sep 6 16:17:07.547 CEST: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 172.16.0.1 (Tunnel1) is down: holding time expired

*Sep 6 16:17:19.631 CEST: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 172.16.0.1 (Tunnel1) is up: new adjacency

*Sep 6 16:17:57.871 CEST: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 172.16.0.1 (Tunnel1) is down: holding time expired

*Sep 6 16:18:05.723 CEST: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 172.16.0.1 (Tunnel1) is up: new adjacency

*Sep 6 16:18:50.675 CEST: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: N


Any ideas ?


BR,


Bjornarsb




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mohindersingh Thu, 09/06/2007 - 06:26
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Hi,


Eigrp neighborship can flap due to several reasons. just enable debugging in the router and try to find out the reason. Copy and send the debug logs.


Thanks

Mahi

Richard Burts Thu, 09/06/2007 - 06:36
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Bjornarsb


The messages indicate that it is over interface tunnel1 from which I assume that this is at least a GRE tunnel and perhaps GRE with IPSec running EIGRP. I have implemented this functionality for a customer (with the tunnel running through the Internet) and we experienced the symptoms of EIGRP flapping like this. We found that if we increased the EIGRP timers for hello-interval and for hold-time on the tunnel interfaces that the symptoms improved. We still experience some neighbor instability but it is much less than it was with the default timers. You might try increasing the EIGRP timers and let us know if it makes any difference in your environment.


HTH


Rick

bjornarsb Thu, 09/06/2007 - 06:53
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Hi,


I've already tried to do this according to the doc.


It does not help:

!

interface Tunnel1

bandwidth 384

ip address 172.16.0.32 255.255.0.0

no ip redirects

ip mtu 1400

ip hello-interval eigrp 1 60

ip hold-time eigrp 1 180


BR,


Bjornarsb

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