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Tag: redundancy

  • How to configure Redundant Supervisor Engine module in Cisco IOS

    Cisco Catalyst Switches like  Catalyst 6500 series and Catalyst 4500-R series and highend routers lsupport Redundant Supervisor modules to be installed. The Redudndant Supervisor Modules startup and run as a standby device and takes over when the active module fails. The Active Supervisor Engine syncs time and config onto the redundant supervisor engine every 1 sec and when running-config is copied to the Start-up config. The failover mode Stateful switchOver (SSO) we use here allows failover in 1 second or more.

    Check your Catalyst switch / Routers and the Supervisor Engine documentation for the supported modes of redundancy.

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  • How to configure HSRP in Cisco IOS Routers

    HSRP stands for Hot Standy Routing Protocol which provides Automatic Router backup when an active router in the group fails. HSRP allows building resiliency in the network gateways wherein should an Active Router fail in a HSRP group, the standby router assumes the role of the active router and continue routing packets.

    HSRP works by sending multicast "Hello" messages (default: every 3 secs). If the Standby router do not receive any Hello packets from the active router for a preset time (default 10secs) then it assumes the active router is down and becomes the active router. Also, if we are tracking an interface and if the tracked interface is down, the Active Router reduces its priority so a Standby Router can assume to role of Primary Router.

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