Quagga router advertisement messages are wrong after an address change

Question

I have a problem with Quagga OSPFv3 implementation. I have a Mininet topology with a host connected to a router.

I assigned an IPv6 address to the router interface. And I enabled IPv6 autoconfiguration in the host

sysctl -w net.ipv6.conf.all.autoconf=1

When I start Mininet, it assign a correct IPv6 address to the host.

But if I change the IPv6 address of the router interface, the host does not get a new address in the new subnet.

The problem is that after the address change the router advertisement messages sent by the router keep on a advertising old prefix. And then the host does not set a new address.

An example:

• in the ospfv3 configuration I assign the address fdf0:0:0:3::1/64
• the router advertises the prefix fdf0:0:0:3::/64 the address
• fdf0:0:0:3::2 is assigned to the host I assign to the router the address
• fc00::1/64 the host address does not change because the router keep on advertising fdf0:0:0:3::/64

So, why this strange behavior?

Answer 1

Simply assigning a new IPv6 address to an interface does not remove the old IPv6 address. IPv6 allows you to assign multiple addresses to one interface, including addresses from different networks.

For example, you will have a link-local IPv6 address. You can then assign multiple global and/or ULA addresses to the interface. In theory, there is no limit to the number of IPv6 addresses you can assign to an interface, but OSes will have a limitation on the number of IPv6 addresses you can assign to an interface.