Refer to the exhibit. A network engineer must improve the current IS-IS environment. The Catalyst switch is equipped with dual supervisors. Each time a stateful switchover occurs, the network…

Question

Exhibit

Options

• AEnable IS-IS remote LFA FRR on both devices.
• BEnable NSR on the switch.
• CEnable NSF on the switch.
• DConfigure ISIS aggressive timers on both devices.

• A
  4% (1)
• B
  78% (18)
• C
  4% (1)
• D
  13% (3)

Explanation

Non-Stop Routing (NSR) synchronizes the IS-IS routing protocol state between the active and standby supervisor engines. During a stateful switchover, the standby supervisor takes over seamlessly and IS-IS adjacencies are preserved from the perspective of the neighbor - no graceful restart messages are exchanged, and the neighbor never detects the switchover. This prevents unnecessary route recomputation on both sides. NSF (Non-Stop Forwarding, option C) relies on graceful restart signaling to neighbors, which requires the neighbor to support it. Since the upstream router does not understand graceful restart, NSF would not function correctly. Remote LFA FRR (A) is a fast reroute mechanism, not a supervisor redundancy solution. Aggressive IS-IS timers (D) would actually increase the impact of any topology change.

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