Explains ISIS Non-Stop Routing (NSR) functionality and guides users through configuration procedures to maintain routing continuity during process restarts.
Non-stop Routing (NSR) is a high availability routing protocol feature that
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suppresses IS-IS routing changes when devices with redundant route processors experience a switchover event
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reduces network instability and downtime by enabling continuous routing during such events, and
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transfers all necessary peering state information from the active to the standby processor to allow immediate protocol resumption upon switchover.
To preserve routing across process restarts, you must configure Non Stop Forwarding (NSF) in addition to NSR.
When NSR is enabled on a router with redundant route processors, switching from the active to the standby processor does not impact other IS-IS routers in the network, as all protocol state is preserved and routing continues seamlessly.