Hi,

what about ospf, how would ABR inject type-3 LSA to other routers if the router-ID is not reachable by some routers in different areas.

Thanks,

Hi there,

Router-ID is just an ID for the router (just like a naming tag), it doesn't have to be reachable at all (i mean routing wise, its just an ID).

HTH,

Mohammed Mahmoud.

Please remember how is created an OSPF adjacency, in particular:

Init: this state specifies that the router has received a hello packet from its neighbor, but the receiving router's ID was not included in the hello packet. When a router receives a hello packet from a neighbor, it should list the sender's router ID in its hello packet as an acknowledgment that it received a valid hello packet.

2-Way: this state designates that bi-directional communication has been established between two routers. Bi-directional means that each router has seen the other's hello packet. This state is attained when the router receiving the hello packet sees its own Router ID within the received hello packet's neighbor field. At this state, a router decides whether to become adjacent with this neighbor.

Router-ID is only a "tag" used to identify routers in the neighborship process.

HTH

Andrea

Hi Andrea,

Thanks for reminding, yes you are right.

Once review it back, I refreshed my memory.

Thanks again,