Advertising a default route in OSPFv3 is somewhat similar to IPv4 OSPF.

Without using the “always” command. First we need to set a static default route. Here we set it to Null0.

# ipv6 route ::/0 Null0

Then we advertise the default route.

# ipv6 router ospf 1

# default-information originate

With the “always” command you do not need a default route to be present in your routing table.

# ipv6 router ospf 1

# default-information originate always

Cheers.