27.5.3 Checking neighboring router information

You can use the show ipv6 ospf neighbor operation command to check the link-local address (Neighbor Address), neighbor state (State), ID (Router ID), and priority of neighboring routers.

On an OSPFv3 interface, the designated router (DR) forms adjacencies with the other routers. You can monitor its progress by checking the State field in the command output.

Full appears as the status of routers that have formed an adjacency. Otherwise, the router is in the process of forming an adjacency with the designated router and cannot learn OSPFv3 routes at its interfaces.

You can examine the neighboring routers in more detail by executing the show ipv6 ospf interface and show ipv6 ospf neighbor detail operation commands. The command output includes the interface state, network type, and connectivity with neighboring routers.

• Make sure that the OSPFv3 network type of the interface is the same as that of its neighboring routers.

• When DR or P to P appears as the interface state, make sure that the status of each neighboring router in the neighbor list is Full.

  • A value other than Full indicates that the interface has not formed an adjacency with the neighboring router. Check the neighboring routers.

• When BackupDR or DR Other appears as the interface state, check whether the neighbor list contains a router that is eligible to be elected the DR.

  • If a DR exists in the neighbor list but its neighboring routers have a status other than Full, this indicates that the interface has not formed an adjacency with the neighboring router. Check the neighboring routers.

  • If no DR exists, this might indicate that no priority has been assigned to the Switch or its neighbors. Check the priority setting for the switch and neighboring routers.

>show ipv6 ospf neighbor
Date 20XX/07/14 12:00:00 UTC
Domain: 1
Area: 0
Neighbor Address          State               Router ID   Priority Interface
fe80::1000:00ff:fe00:2002 Full/BackupDR       172.16.10.12       1 VLAN0003
fe80::1000:00ff:fe00:2003 Full/DR Other       172.16.10.13       1 VLAN0003
fe80::1000:00ff:fe00:2004 Exch Start/DR Other 172.126.10.14      1 VLAN0003

>show ipv6 ospf interface vlan 10
Date 20XX/05/30 12:00:00 UTC
Domain: 1
Area: 0
Interface ID: 2,Link Local Address : fe80::1000:00ff:fe00:0001%VLAN0010
    IPv6 Address: -
    MTU: 1460, DDinPacket: 71, LSRinPacket: 120, ACKinPacket:72
    Router ID: 172.16.1.1, Network Type: P to P, State: P to P
    DR: none, Backup DR: none
    Priority: 0, Cost: 1, Instance: 0
    Transmit Delay: 1s
    Intervals:
        Hello: 10s, Dead: 40s, Retransmit: 5s
 
  Neighbor List (1):
    Address                     State        Router ID         Priority
    fe80::1000:00ff:fe00:2002   Full         172.16.1.2           0
>

>show ipv6 ospf neighbor detail
Date 20XX/05/30 12:00:00 UTC
Domain: 1
Area: 0
Interface: VLAN0020, Interface State: Backup DR
    Neighbor Address: fe80::1000:00ff:fe00:2002, State: Full/DR
    Neighbor Router ID: 172.16.10.11, Priority: 1
    Neighbor Interface ID: 2
    DR: 172.16.10.11, Backup DR: 172.16.10.10
    Last Hello: 6s, Last Exchange: 45d 12h
    DS: 0, LSR: 0, Retrans: 0, <Master>
    Neighbor Address: fe80::1000:00ff:fe00:2001, State: Full/DR Other
    Neighbor Router ID: 172.16.10.12, Priority: 1
    Neighbor Interface ID: 404
    DR: 172.16.10.11, Backup DR: 172.16.10.10
    Last Hello:  3s, Last Exchange:  1m  8s
    DS: 0, LSR: 0, Retrans: 1, <>
>