High RTO with low SSRT values on EIGRP

[spfister336]

We are running several remote sites connecting back to a central site using EIGRP as the routing protocol over AT&T's ASE on demand switched ethernet service. It's been mostly fine, but occasionally for 25 or 30 minutes we get a lot of flapping that seems to go away on its own. During this time, 'show ip eigrp neigh' shows lines like:

31 10.210.77.2 Vl277 13 00:00:40 1 5000 1 806
26 10.210.43.2 Vl243 13 00:00:40 1 100 0 124
20 10.210.15.2 Vl215 11 00:00:40 1 100 0 413
9 10.210.81.2 Vl281 13 00:00:40 2 1702 0 100
4 10.210.17.2 Vl217 14 00:00:40 1 5000 1 1072
29 10.210.66.2 Vl266 13 00:00:46 1 5000 1 462
25 10.210.71.2 Vl271 13 00:00:46 1 5000 1 2129
24 10.210.22.2 Vl322 14 00:00:46 17 771 1 1493

The SRTT values seem relatively OK, but the RTOs go into the thousands. Is it possible that this is packet loss, or multicast rate limiting on AT&T's part?

[MHM Cisco World]

there is increase in Hello in send/receive so I think about using debug for eigrp but there are many neighbour and this nightmare so 
I try in lab and find away to tune the debug for specific neighbour (neighbour that flapping )
debug eigrp packet hello 10 <<- 10 is standard ACL I use to specify only one host 

[Yousif Ahmed]

Cisco TAC Engineer Conclusion:

*** Conclusion:*



EIGRP Hellos are being lost in the middle
-Check with the ISP why EIGRP hellos are being dropped.

[MHM Cisco World]

Yes as i mention above hello is unrelaible message and it lost and make neighbor flapping'

But the Q why it happened to some neighbor'

What flapping neighbor different that stable neighbor?

That in my Mind

[Yousif Ahmed]

It's happening to all AT&T Neighbors. There are no stable neighbors, the only stable ones that we have are not related to AT&T Pipe.

[MHM Cisco World]

Bingo' 

Then that sure as TAC and as I see it SP issue it not your issue.

So as I mention earlier it link to neighbor flapping.

Thanks  alot'

Hope update me when get reply from at&t.

Have a nice day 

Thanks again 

MHM

[Yousif Ahmed]

Wish me luck with communicating with AT&T...

[MHM Cisco World]

I wishing you good luck friend

Have a great weekend.

[Yousif Ahmed]

Updates from the ISP

#1 Currently exceeding BUM limits. - We already enabled enhanced multicast, but the system is so bugged that it did not enable it. They are researching how to up the BUM limit to 30 mbps..

#2 More MAC address learning than expected….should only see x MAC addresses (1 MAC per router interface) - Since we are port based, they should only be seeing ATT Routers, that's it. But in this case it seems like they are able to see more than just the ATT Routers on the circuits. Suggestions on this would be appreciated if any.