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MPLS and RSVP
Uniform FRR Failover Time
The failover time during FRR consists of a detection time and a switchover time. The detection
time corresponds to the time it takes for the RSVP control plane protocol to detect that a network
IP interface is down or that a neighbor/next-hop over a network IP interface is down. The control
plane can be informed of an interface down event when event is due to a failure in a lower layer
such in the physical layer. The control plane can also detect the failure of a neighbor/next-hop on
its own by running a protocol such as Hello, Keep-Alive, or BFD.
The switchover time is measured from the time the control plane detected the failure of the
interface or neighbor/next-hop to the time the XCM completed the reprogramming of all the
impacted ILM or service records in the data path. This includes the time it takes for the control
plane to send a down notification to all XCMs to request a switch to the backup NHLFE.
Uniform Fast-Reroute (FRR) failover enables the switchover of MPLS and service packets from
the outgoing interface of the primary LSP path to that of the FRR backup LSP within the same
amount of time regardless of the number of LSPs or service records. This is achieved by updating
Ingress Label Map (ILM) records and service records to point to the backup Next-Hop Label to
Forwarding Entry (NHLFE) in a single operation.
7950 SR OS MPLS Configuration Guide
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