[c-nsp] IPv6 ns-interval & 12.2(33)SRE & ASA 8.2(2)

[Timothy Arnold]

Hi Guys,
I'm hoping there is someone out there who knows a bit more about IPv6 that I do :)

Enabled ipv6 between the Cisco 7600 running 12.2(33)SRE and a pair of Cisco ASA firewalls running 8.2(2) (in HA). I get the following from the 7600

%IPV6-3-CONFLICT: Router FE80::21A:E2FF:FE68:50AA on Vlan2008 has conflicting ND settings

"show ipv6 routers" show the only real difference is the retransmit time. On the 7600, it is 0ms (which I understand to be "unspecified" rather than 0) and on the ASA the default is 1000.

cr1-sdf2.uk#show ipv6 routers vlan2008
Router FE80::21A:E2FF:FE68:50AA on Vlan2008, last update 0 min, CONFLICT
  Hops 64, Lifetime 1800 sec, AddrFlag=0, OtherFlag=0, MTU=1500
  HomeAgentFlag=0, Preference=Medium
  Reachable time 0 msec, Retransmit time 1000 msec
  Prefix 2A02:298:0:4::/112 onlink autoconfig
    Valid lifetime 2592000, preferred lifetime 604800

colofw1/act# show ipv6 routers
Router fe80::21b:dff:fee5:ae00 on outside, last update 0 min
  Hops 64, Lifetime 1800 sec, AddrFlag=0, OtherFlag=0, MTU=1500
  Reachable time 0 msec, Retransmit time 0 msec
  Prefix 2a02:298:0:4::/112 onlink autoconfig
    Valid lifetime 2592000, preferred lifetime 604800

Adding the following configuration to the 7600 corrects the issue:

ipv6 nd ns-interval 1000

cr1-sdf2.uk(config-if)#do show ipv6 routers vlan2008
Router FE80::21A:E2FF:FE68:50AA on Vlan2008, last update 0 min
  Hops 64, Lifetime 1800 sec, AddrFlag=0, OtherFlag=0, MTU=1500
  HomeAgentFlag=0, Preference=Medium
  Reachable time 0 msec, Retransmit time 1000 msec
  Prefix 2A02:298:0:4::/112 onlink autoconfig
    Valid lifetime 2592000, preferred lifetime 604800

Both ends are now the same and no conflict occurs. Any ideas why it's complaining? I thought that the unspecified nature of ns-interval means that it would accept the 1000 milliseconds from the other end?

Thanks
Tim



Timothy Arnold
Senior Engineer, Operations (Network, Security & Facilities Group), UKSolutions

Telephone: 0845 004 1333, option 2
Email: timothy.arnold at uksolutions.co.uk
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