[c-nsp] Troubleshooting OSPFv3 "Neighbor Down: Too many retransmits"

[Devon True]

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All:

I am troubleshooting an issue between two 7600 routers running
12.2(33)SRE3. The ospfv3 session between these two routers keeps going
down and up. Other ospfv2/v3 sessions on either router do not have this
problem.

Mar  1 18:44:22 ROUTER notice 4645: Mar  1 13:44:21.465 Eastern:
%OSPFv3-5-ADJCHG: Process 19271, Nbr x.y.161.253 on GigabitEthernet3/2
from FULL to DOWN, Neighbor Down: Too many retransmits
Mar  1 18:45:23 ROUTER notice 4646: Mar  1 13:45:22.926 Eastern:
%OSPFv3-5-ADJCHG: Process 19271, Nbr x.y.161.253 on GigabitEthernet3/2
from LOADING to FULL, Loading Done
Mar  1 18:47:27 ROUTER notice 4647: Mar  1 13:47:26.216 Eastern:
%OSPFv3-5-ADJCHG: Process 19271, Nbr x.y.161.253 on GigabitEthernet3/2
from FULL to DOWN, Neighbor Down: Too many retransmits

This occurs approximately every 3 minutes.

Troubleshooting steps I have tried:

* applied ipv6 ospf mtu-ignore
* removed ipv6 ospf configuration from interface and re-applied
* passive-interface -> no passive-interface

- -- ospfv3 interface configuration --

 ipv6 ospf network point-to-point
 ipv6 ospf cost 350
 ipv6 ospf 1 area 0

- -- show ipv6 ospf neighbor from router logging "too many retransmits" --

#sh ipv6 ospf neighbor g3/2 detail
 Neighbor x.y.161.253
    In the area 0 via interface GigabitEthernet3/2
    Neighbor: interface-id 14, link-local address FE80::106:C2
    Neighbor priority is 0, State is FULL, 6 state changes
    Options is 0x000013 in Hello (V6-Bit, E-Bit, R-bit)
    Options is 0x000013 in DBD (V6-Bit, E-Bit, R-bit)
    Dead timer due in 00:00:38
    Neighbor is up for 00:01:29
    Index 1/7/7, retransmission queue length 4, number of retransmission 19
    First 0x0(0)/0x543B7C10(26714)/0x543B6B80(9515088) Next
0x0(0)/0x543B7C10(26714)/0x543B6B80(9515088)
    Last retransmission scan length is 1, maximum is 1
    Last retransmission scan time is 0 msec, maximum is 0 msec
    Link State retransmission due in 529 msec

#sh ipv6 ospf neighbor g3/2 detail
 Neighbor x.y.161.253
    In the area 0 via interface GigabitEthernet3/2
    Neighbor: interface-id 14, link-local address FE80::106:C2
    Neighbor priority is 0, State is DOWN, 7 state changes
    Neighbor ignored, reenable in 00:00:10
    Options is 0x000013 in Hello (V6-Bit, E-Bit, R-bit)
    Index 0/0/0, retransmission queue length 0, number of retransmission 27
    First 0x0(0)/0x0(0)/0x0(0) Next 0x0(0)/0x0(0)/0x0(0)
    Last retransmission scan length is 1, maximum is 1
    Last retransmission scan time is 0 msec, maximum is 0 msec

Any other things I can look at before opening a TAC case?

- -- 
Devon
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