What is Supervisor Redundancy?

RPR

--> RPR Stands for Route Processor Redundancy

--> In RPR mode, the active supervisor does not synchronize configuration changes or state information with the standby supervisor.

--> The standby supervisor is only partially initialized and the switching modules on the standby supervisor are not powered up.

--> If a switchover occurs, the standby supervisor completes its initialization and powers up the switching modules.

--> Traffic is disrupted for the normal reboot time of the supervisor.

--> Failover takes around 5 minutes.



RPR +

--> RPR+ Stands for Route Processor Redundancy +

--> The Standby Supervisor is partially initialized but does not need to reload each switch module after Active Supervisor fails.

--> The Standby Supervisor synchronizes the IOS image and the startup configuration with Active Supervisor.

--> The Standby Supervisor does not have Adjacency Table or FIB Table synchronized with Active Supervisor.

--> All the tables must be rebuilt after Standby Supervisor is initialized.

--> Failover takes around 1 minute.

SSO

--> SSO stands for Stateful Switchover.

--> The Standby Supervisor is completely initialized and layer 2 information is synchronized with the Active Supervisor.

--> If the active supervisor engine fails, the standby supervisor engine become active.

--> Layer 3 forwarding will be delayed until the routing tables have been repopulated in the newly active supervisor engine.

--> Failover takes 2-4 seconds.

NSF (Non-Stop Forwarding)

--> NSF is used to keep a switch forwarding traffic during a failover of Active Supervisor.

--> It works in conjunction with SSO.

--> The main purpose of NSF ensures that the switch continues to forward traffic during Stateful Switchover.

--> Cisco NSF is supported by the BGP, OSPF, EIGRP, and IS-IS protocols for routing and is supported by Cisco Express Forwarding (CEF) for forwarding.

--> The routing protocols have been enhanced with NSF-capability and awareness, which means that routers running these protocols can detect a switchover and take the necessary actions to continue forwarding network traffic and to recover route information from the peer devices. 

Reference: Cisco.com

Md.Kareemoddin


CCIE # 54759

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