EIGRP direct neighbors flapping - Page 2

the-lebowski · ‎02-07-2019

Having a problem with a 2 neighrbors losing their EIGRP adjacency:

2951 gi0/11.2 >>>>>>>>>>> 3850 gi1/0/45

They are connected directly to each other but sometime last night it started to lose the adjacency. I went as so far as to statically configure them as neighbors which didn't fix it. The 2951 has 2 other EIGRP neighbors which it doesn't drop connectivity between, its just between itself and the 3850. I do see the Q count as 1 on both sides and debug shows, what looks to me, like the 3850 stops sending packets back to the 2951.

I am also seeing weird routing issues on some of the VLANs on the 3850 as well, some are passing traffic while others aren't. I tried power cycling the 3850 but it made no difference. I have read all types of horror stories about 3850 bugs but no idea if this just another issue with a 3850. Its currently on 16.3.6 and wondering if an upgrade might help at this point.

router eigrp 3000
 distribute-list 90 out Tunnel1
 network 10.1.100.0 0.0.0.255
 network 10.1.200.0 0.0.0.255
 network 10.119.2.0 0.0.0.255
 redistribute static route-map lab
 neighbor 10.119.2.1 GigabitEthernet0/1.2
 eigrp router-id 10.119.2.2

router eigrp 3000
network 10.119.2.0 0.0.0.255
 neighbor 10.119.2.2 Vlan2
 eigrp stub connected summary
snmp-server enable traps eigrp
snmp-server enable traps ipsla
snmp-server enable traps syslog

010173: Feb  7 20:27:21.553: EIGRP: Sending UPDATE on Gi0/1.2 - paklen 0 nbr 10.119.2.1, retry 5, RTO 5000 tid 0
010174: Feb  7 20:27:21.553:   AS 3000, Flags 0x1:(INIT), Seq 9164/124 interfaceQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1
010175: Feb  7 20:27:21.565: EIGRP: Received UPDATE on Gi0/1.2 - paklen 0 nbr 10.119.2.1
010176: Feb  7 20:27:21.565:   AS 3000, Flags 0x1:(INIT), Seq 124/0 interfaceQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1, last received seq 124, out of sequence, this seq 124

010183: Feb  7 20:27:24.813: EIGRP: Received HELLO on Gi0/1.2 - paklen 26 nbr 10.119.2.1
010184: Feb  7 20:27:24.813:   AS 3000, Flags 0x0:(NULL), Seq 0/0 interfaceQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1
010185: Feb  7 20:27:24.813: EIGRP: Received Peer Info from AS 203882497(10.119.2.1), old info, ignored
010186: Feb  7 20:27:25.217: EIGRP: Sending HELLO on Gi0/1.2 - paklen 20 nbr 10.119.2.1
010187: Feb  7 20:27:25.217:   AS 3000, Flags 0x0:(NULL), Seq 0/0 interfaceQ 0/0 iidbQ un/rely 0/0

the-lebowski · ‎02-07-2019

Not yet but there are only 2 routers that I manage in this network and neither of them were causing it that I can tell. The only thing I can think of was maybe an L2 loop somewhere downstream that would allow the router to see the router-id coming back to itself? Is that a possibility?

I rated your posts helpful.

grabonlee · ‎02-07-2019

Barring any possibility of a router with same Router-ID somewhere in your network redistributing routes, it's likely that the 3850 is getting a feedback, which could also attributed to Layer 2. I can't definitely pin-point, but I would just suggest reviewing your network at both Layer 2 and 3 including the Spanning root for your VLANs. It helps to make a network deterministic.