OSPv3...from Global Configuration or Interface Mode?

[JoshGarmonCiscoCCNA]

1.) Do you configure it from Global Configuration mode or per Interface?

2.) Do you have to have a loopback already created before configuring the router-id

[Masoud Pourshabanian]

Some of the configuration is done in global mode and some under each interface.

Just a raw example:

Global :

ipv6 router ospf 1

router-id 2.2.2.2

default metric 30

Under interface:

interface f0/0

Ipv6 enable

ipv6 ospf 1 area 0

Router-id is an optional command. If you do not specify router-id command, router picks the highest IP address of a loopback interface.  Having loopback interface is also optional. If you want router to pick your loopback address as a router id, you need to create loopback at first. If you do not do that, you need to restart your ospf process to fix that.

Hope it helps,

Masoud