What is stateful switchover?

SSO is a feature for RP redundancy within a single device, not a cluster protocol used to facilitate failover among multiple switches.

Stateful Switchover (SSO) is a redundancy mechanism where a standby Route Processor (RP) maintains synchronized state information (such as forwarding tables, NAT translations, and established sessions) with the active RP. Upon active RP failure, the standby RP seamlessly takes over without disrupting existing data plane traffic or network connectivity, ensuring continuous operation.

While SSO aims to prevent disruption during RP switchover, its primary function is state synchronization and seamless takeover, not specifically preventing routing protocol loops which are typically handled by routing protocol mechanisms.

First Hop Redundancy Protocols (FHRPs) like HSRP or VRRP provide gateway redundancy for end hosts, which is distinct from RP redundancy within a router provided by SSO.