What are three ways that graceful Routing Engine switchover provides redundancy? (Choose three.)
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A. B. C. D. E.ABE
Graceful Routing Engine switchover (GRES) is a feature provided by Juniper Networks routers and switches that offers redundancy by minimizing the impact of a Routing Engine (RE) failure. When a Routing Engine fails, GRES ensures that the network continues to function without significant disruption. There are several ways in which GRES provides redundancy, including:
A. Preserving interface and kernel information: When GRES is enabled, the backup RE is able to maintain the same interface and kernel information as the failed RE. This allows for a smoother transition during failover, as the new RE does not have to relearn this information. The preservation of this information also ensures that the network continues to function normally, as the new RE is able to seamlessly take over the responsibilities of the failed RE.
B. Reducing time of RE failover: GRES reduces the time it takes for the backup RE to take over the responsibilities of the failed RE. When GRES is enabled, the backup RE is preloaded with the necessary information to take over, and the time it takes to switch over is minimized. This ensures that the network experiences minimal downtime, and that the impact of the failure is reduced.
C. Preserving the data plane information: GRES preserves the data plane information, allowing the new RE to take over the forwarding responsibilities of the failed RE seamlessly. This ensures that packets continue to be forwarded correctly, and that there is no interruption in the flow of traffic. The preservation of data plane information also ensures that the network continues to function normally, even in the event of a Routing Engine failure.
D. Preserving the control plane information: GRES preserves the control plane information, ensuring that the new RE has access to the same routing tables and protocol information as the failed RE. This ensures that the new RE is able to continue performing the same functions as the failed RE, and that there is no interruption in the flow of control plane traffic.
E. Not restarting the PFE: In some cases, GRES is able to preserve the state of the Packet Forwarding Engine (PFE) during a failover, meaning that the PFE does not need to be restarted. This reduces the impact of the failover on the network, as it minimizes the time it takes for the new RE to take over the forwarding responsibilities of the failed RE.
In summary, Graceful Routing Engine switchover provides redundancy by preserving interface and kernel information, reducing the time of RE failover, preserving data plane and control plane information, and in some cases, not restarting the PFE.