Which feature is required for graceful restart to recover from a processor failure?
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A. B. C. D.A.
The correct answer to this question is C. Stateful Switchover (SSO).
Stateful Switchover is a feature on Cisco IOS routers and switches that allows the devices to continue forwarding packets during a supervisor engine or routing engine failover. SSO maintains the state information of the active supervisor engine and synchronizes this information with the standby supervisor engine. This ensures that the standby engine can take over and continue forwarding packets without any interruption or loss of traffic.
Graceful Restart is another feature on Cisco IOS routers and switches that enables network devices to continue forwarding traffic while undergoing a control-plane switchover. Graceful Restart is used to minimize the impact of a control-plane switchover on network traffic. During a control-plane switchover, the forwarding plane is not affected, but the control-plane restart can cause network traffic to be disrupted.
Graceful Restart, however, requires Stateful Switchover to recover from a processor failure. If the active supervisor engine fails, SSO ensures that the standby engine takes over and resumes forwarding packets while maintaining the state information of the failed engine. During this time, the device is in the Graceful Restart process and will continue to forward traffic without interruption.
Cisco Express Forwarding (CEF) is a switching technology that is used to optimize network performance. Virtual Switch System (VSS) is a Cisco technology that combines two physical switches into a single virtual switch to provide high availability and increased bandwidth. Bidirectional Forwarding Detection (BFD) is a protocol used to provide fast detection of network failures.
Therefore, the correct answer to the question is C. Stateful Switchover.