Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) — Question 344

What happens when a segment-routing TE tunnel loses the link and there is no secondary path in place?

Answer options

• A. The headend router generates a new path to the tail-end router using bandwidth to determine the best path.
• B. The headend router starts the invalidation timer to bring the tunnel down.
• C. The tail-end router sends an alert to the syslog server that the tunnel and the secondary route are inaccessible.
• D. The headend and tail-end routers revalidate SID hops to determine the proper label stack to reroute the traffic.

Correct answer: B

Explanation

The correct answer is B because when a primary path fails and there is no secondary path, the headend router initiates the invalidation timer to bring the tunnel down. Option A is incorrect as the headend does not generate a new path without a secondary one. Option C is not applicable since the tail-end router does not send alerts to the syslog server in this scenario. Option D is also wrong because revalidating SID hops is not done when the tunnel is lost without an alternative route.