Comprehensive and Detailed In-Depth Explanation:
In IS-IS, routes are distributed differently based on router levels:
Level-1 (L1) routers → Maintain specific routes only within their own area.
Level-2 (L2) routers → Maintain specific routes for the entire network (inter-area routing).
Level-1-2 (L1/L2) routers → Store both L1 and L2 routes and act as area border routers.
In the diagram, R2 and R3 are L1/L2 routers, meaning they store specific routes for both their area and other areas.
R1 is only an L1 router, meaning it only has intra-area routes, and R7 is an L2-only router, meaning it does not store all specific routes.
Therefore, R2 and R3 have specific routes for the entire network.
???? Reference: Huawei HCIA-Datacom Study Guide, IS-IS Routing Levels and Route Distribution.
Submit