Nonstop active routing (NSR) allows a routing platform with redundant Routing Engines to switch over from a primary Routing Engine to a backup Routing Engine without alerting peer nodes that a change has occurred. NSR uses the same infrastructure as graceful Routing Engine switchover (GRES) to preserve interface and kernel information. However, NSR also saves routing protocol information by running the routing protocol (rpd) process on the backup Routing Engine. Saving this additional information makes NSR self-contained and eliminates the need for helper routers to assist the routing platform in restoring routing protocol information. As a result of this enhanced functionality, NSR is a natural replacement for graceful restart protocol extensions.
If the kernel on the master Routing Engine stops operating, the master Routing Engine experiences a hardware failure, or the administrator initiates a manual switchover, mastership switches to the backup Routing Engine. To configure NSR, you must first enable GRES on your routing platform. For more information about how to configure GRES, see the JUNOS High Availability Configuration Guide.
To enable NSR, include the nonstop-routing statement at the [edit routing-options] hierarchy level.
- [edit routing-options]
Note: You cannot configure NSR and graceful restart protocol extensions simultaneously. To ensure proper operation, include either the nonstop-routing statement or the graceful-restart statement at the hierarchy level, but not both statements at the same time.
For more detailed information about NSR, see the JUNOS High Availability Configuration Guide.