I am working with a cisco router model 2900 which has four gigabitethernet 0/0/0 - 0/0/3.

They do accept ipv4 addresses, however they will not accept ipv6 address. I have tried to use svi (assigning it ipv4 and ipv6 addresses) and remove the ipv4 address from the gigabitethernet interface, using the access vlan command but that did not seem to work.

How do you assign an ipv6 address to those interfaces?

  • 2
    What IOS version is it running? Jul 6, 2019 at 10:43
  • A 2900, and a 3 segment interface number? That is probably a swich module ; its ports should not even accept any layer 3 configuration bits, but are switch ports - any layer 3 config for them should be done via SVI resp. interface vlan XXX. Can you please add the output of show inventory and show version to the question? Jul 6, 2019 at 12:07

1 Answer 1


I haven't touched this model for quite some time but maybe you need to enable ipv6 with enable ipv6 first. In case you want to to IPv6 routing also enable it with ipv6 unicast-routing

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