[c-nsp] OSPF flapping between Nexus 7000 and ASR 1001x

[Adrian Minta]

Multicast.

On 7/9/19 6:58 PM, Richard Mikisa wrote:
> Hi All,
>
> I am running OSPF across a point to point link between a Nexus 7000
> and an ASR1000x.
>
> The OSPF works fine but every couple of hours, it breaks and neighbor
> state goes into EXCHANGE and remains there for another 40 minutes or
> so. It then goes into full, OSPF comes up and all is well for another
> couple of hours or so and then the cycle starts again. All the time,
> IP connectivity between the two point to point IPs is up.
>
> Configuration as below..
>
> ASR1001x#sh run int g0/0/1
> interface GigabitEthernet0/0/1
>   description ** MPLS London -  SO031732 **
>   mtu 9216
>   ip address 10.32.250.17 255.255.255.252
>   ip ospf network point-to-point
>   ip ospf mtu-ignore
>   negotiation auto
>   cdp enable
> end
>
> ASR1000x#sh ip ospf neighbor
>
> Neighbor ID     Pri   State           Dead Time   Address         Interface
> 40.1.1.1          0   EXCHANGE/  -    00:00:33    10.32.250.18
> GigabitEtherne
>                      t0/0/1
> 10.32.8.253       1   FULL/DR         00:00:32    10.32.250.1
> GigabitEtherne
>                      t0/0/0
>
>
> On the Nexus
> N7K1-LON-AGG# sh run int vlan 3960
>
> interface Vlan3960
>    no shutdown
>    mtu 9216
>    ip address 10.32.250.18/30
>    ip ospf cost 1
>    ip ospf network point-to-point
>    no ip ospf passive-interface
>    ip ospf mtu-ignore
>    ip router ospf 100 area 0.0.0.32
>
> N7K1-LON-AGG# sh ip ospf neighbors 10.32.250.2
>   OSPF Process ID 100 VRF default
>   Total number of neighbors: 15
>   Neighbor ID     Pri State            Up Time  Address         Interface
>   10.32.250.2       1 EXCHANGE/ -      00:05:06 10.32.250.17    Vlan3960
> N7K1-LON-AGG#
>
> And the logs on the ASR
>
> Jul  9 14:33:00.682: %OSPF-5-ADJCHG: Process 100, Nbr 40.1.1.1 on
> GigabitEthernet0/0/1 from FULL to DOWN, Neighbor Down: Too many
> retransmissions
> Jul  9 14:34:00.683: %OSPF-5-ADJCHG: Process 100, Nbr 40.1.1.1 on
> GigabitEthernet0/0/1 from DOWN to DOWN, Neighbor Down: Ignore timer
> expired
> Jul  9 14:34:46.962: %CLNS-5-ADJCHANGE: ISIS (Overlay1): Adjacency to
> N7K1-LON-OTV (Overlay1) Down, hold time expired
> Jul  9 14:39:56.543: %OSPF-5-ADJCHG: Process 100, Nbr 40.1.1.1 on
> GigabitEthernet0/0/1 from EXCHANGE to DOWN, Neighbor Down: Interface
> down or detached
> Jul  9 14:55:20.865: %OSPF-5-ADJCHG: Process 100, Nbr 40.1.1.1 on
> GigabitEthernet0/0/1 from EXCHANGE to DOWN, Neighbor Down: Interface
> down or detached
> .Jul  9 15:06:25.955: %OSPF-5-ADJCHG: Process 100, Nbr 40.1.1.1 on
> GigabitEthernet0/0/1 from EXCHANGE to DOWN, Neighbor Down: Too many
> retransmissions
> .Jul  9 15:07:25.955: %OSPF-5-ADJCHG: Process 100, Nbr 40.1.1.1 on
> GigabitEthernet0/0/1 from DOWN to DOWN, Neighbor Down: Ignore timer
> expired
> .Jul  9 15:37:57.514: %OSPF-5-ADJCHG: Process 100, Nbr 40.1.1.1 on
> GigabitEthernet0/0/1 from LOADING to FULL, Loading Done
> .Jul  9 15:38:03.296: %CLNS-5-ADJCHANGE: ISIS (Overlay1): Adjacency to
> 8478.AC22.FEC3 (Overlay1) Up, new adjacency
> .Jul  9 15:42:25.399: %SEC_LOGIN-5-LOGIN_SUCCESS: Login Success [user:
> richard.mikisa] [Source: 10.0.1.2] [localport: 22] at 15:42:25 UTC Tue
> Jul 9 2019
>
>
> Can someone advise on where to look?

-- 
Best regards,
Adrian Minta