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Ipv6 Vlan Interface EUI-64 assignation problem

Hello, I have 2 routers 1800 series with switch modules incorporated connected with IPv6. Everything is working fine except for the problem that when I assign an IPv6 address to a Vlan (using the EUI-64 format to the switch ports), it assigns the SAME interface id (last 64 bits of the IPv6) of a fastEthernet port (FE 0/0), to the vlan, causing an error problem of duplicity:

" c..T, overlaps with another prefix "

Why does the EUI-64 assigns the MAC address of the FastEthernet ports instead of the ones in the switch modules?


Re: Ipv6 Vlan Interface EUI-64 assignation problem


Would you be able to post the relevant bits of your config ?



Re: Ipv6 Vlan Interface EUI-64 assignation problem

Thanks for the reply, but I just solved the problem. The problem was with the command IPV6 ADDRESS AUTOCONFIGURATION. This command definitely brings up a lot of trouble with VLAN ipv6 address assignation.

After some testing I concluded that:

1- If one interface has the IPV6 ADDRESS AUTOCONFIGURATION mode on, the interface could end up with more than one ipv6 global interface address.

2- You cannot assign this mode to a vlan interface without getting into configuration problems.

3- If a FastEthernet Interface has this mode on(IPV& A. A.), the router does not let you assign a global unicast address to the vlan interface, and gives the following error message:

%IPV6-6-ADDRESS: 3FFE:C00:C18:F100:213:C4FF:FE44:4961/64 can not be configurex

4- For the VLAN`s Interface ID you have to manually assign the link local address with the command line

IPV6 ADDRESS FE80::1 (or any other unique link local address) LINK-LOCAL.

This is for Vlans that are in a switch module of the same router.

All this testing was for a Cisco router 1800 series with a switch module integrated in the router.

Could be that this command is used for other specific occasions which I am not aware of.


Grupo GTD