300-420 Question 80
Select 3A network engineer is designing a highly available enterprise network and plans to use the Graceful Restart (GR) mechanism to minimize the impact of control plane failures on traffic forwarding. Which of the following statements correctly describe the behavior of Graceful Restart in this scenario?
- A
Graceful Restart allows routers to maintain forwarding operations while the control plane recovers.
- B
Graceful Restart relies on helper routers to assist the restarting router in maintaining traffic forwarding.
- C
Graceful Restart works independently of any routing protocol and does not require protocol-specific support.
- D
If the restarting router's control plane does not recover within a specified timer, helper routers terminate the GR session.
- E
Graceful Restart ensures that no packet loss occurs during the control plane recovery process.
Show answer and explanation
Correct answers: A, B, D
Explanation
Graceful Restart is a mechanism used to enhance network stability during control plane failures. It allows a router to continue forwarding traffic while its control plane restarts, with the assistance of helper routers maintaining the forwarding state. However, it is protocol-specific and requires configuration in routing protocols. If the control plane recovery exceeds the GR timer, helper routers terminate the session to avoid prolonged instability. While it minimizes disruption, it does not guarantee zero packet loss.
- A. Correct.
Correct: Graceful Restart enables routers to keep forwarding traffic while the control plane is recovering, ensuring minimal disruption.
- B. Correct.
Correct: Helper routers play a critical role in Graceful Restart by maintaining the forwarding state for the restarting router.
- C. Incorrect.
Incorrect: Graceful Restart is protocol-specific and requires explicit support and configuration in routing protocols like OSPF, BGP, or IS-IS.
- D. Correct.
Correct: If the control plane recovery does not complete within the Graceful Restart timer, helper routers terminate their assistance to avoid prolonged instability.
- E. Incorrect.
Incorrect: Graceful Restart minimizes disruption but does not guarantee zero packet loss during the recovery process.