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    Monitoring Received IPv6 Router Advertisements

    Purpose

    Display IPv6 router advertisement information received. You can use the conflicts keyword to display router advertisements that differ from the advertisements configured.

    Action

    To display IPv6 router advertisement information received:

    host1#show ipv6 routers
    Router FE80::83B3:60A4 on FastEthernet2/0, last update 3 min
      Hops 0, Lifetime 6000 sec, AddrFlag=0, OtherFlag=0
      Reachable time 0 msec, Retransmit time 0 msec
      Prefix 3FFE:C00:8007::800:207C:4E37/96 autoconfig
        Valid lifetime -1, preferred lifetime -1
    Router FE80::290:27FF:FE8C:B709 on FastEthernet2/1, last update 0 min
      Hops 64, Lifetime 1800 sec, AddrFlag=0, OtherFlag=0
      Reachable time 0 msec, Retransmit time 0 msec 

    To display router advertisements that differ from the advertisements configured:

    host1#show ipv6 routers conflicts
    Router FE80::203:FDFF:FE34:7039 on FastEthernet1/0, last update 1 min, CONFLICT
       Hops 64, Lifetime 1800 sec, AddrFlag=0, OtherFlag=0
       Reachable time 0 msec, Retransmit time 0 msec
       Prefix 2003::/64 onlink autoconfig
         Valid lifetime -1, preferred lifetime -1

    Meaning

    Table 1 lists the show ipv6 routers command output fields.

    Table 1: show ipv6 routers Output Fields

    Field Name

    Field Description

    Router

    Router for which this information applies

    Hops

    Number of hops that the router uses in router advertisements

    Lifetime

    Lifetime (in seconds) of the neighbor discovery router advertisement

    AddrFlag

    State of the neighbor discovery router advertisement managed flag

    OtherFlag

    State of the neighbor discovery router advertisement other config flag

    Reachable time

    Amount of time (in milliseconds) that the neighbor is expected to remain reachable

    Retransmit time

    Interval in which the router retransmits neighbor solicitations

    Prefix

    IPv6 network number to include in router advertisements

    Autoconfig

    When present, indicates that local host links use the specified prefix for IPv6 autoconfiguration

    Valid lifetime

    Amount of time in seconds that the router advertises the IPv6 prefix as valid

    preferred lifetime

    Amount of time in seconds that the router advertises the specified IPv6 prefix as preferred

    Published: 2014-08-13