4A0-112 Exam Dumps : Nokia IS-IS Routing Protocol

From the output, we can see that theusagecolumn indicates whether a router is operating as an L1 or L2 router:

RoutersR1andR2have a usage ofL2, meaning they are L2 routers.

RoutersR3andR4have a usage ofL1, meaning they are L1 routers.

TheL1/L2designations refer to whether the routers participate in both Level 1 and Level 2 of IS-IS:

L1 routersonly communicate within their own area.

L2 routerscommunicate between areas.

In this case,R1andR2are L2 routers, andR3andR4are L1 routers.

Typically, interfaces on a Nokia 7750 SR router are not configured in pairs on the same subnet for redundancy. Instead, redundancy is achieved through mechanisms like Virtual Router Redundancy Protocol (VRRP) or other high availability protocols, not by simply using interfaces in pairs on the same subnet.

From R1 to R7: The path will be R1 → R2 → R4 → R6 → R7 because this path has the least cumulative metric of 10 + 10 + 10 + 10 = 40.

From R7 to R1: The reverse path will follow R7 → R6 → R4 → R2 → R1 because it is the shortest return path with the same metrics.