Hi,I'm not sure if I'm looking at the right picture.I could not reach the URL you sent.I'm looking at a white paper called "Introduction to Intermediate System-to-Intermediate System Protocol.In Fig. 2, the scenario is as you describe. By "connected"...

Change the word "routes" to "packets" in the last sentence.

Yes, an L1L2 router can be connected to several areas, but it can only belong to one area.I guess that L1 routers and ESs in an isis area only knows about the other routers and ESs in its area.If an ES or L1 node wants to reach another node in a diff...