Overview

A network with High Availability provides alternate means by which all infrastructure paths and key servers can be accessed at all times. The Hot Standby Routing Protocol is one of those software features configured to provide Layer 3 redundancy to network hosts. HSRP optimization provides immediate or link specific failover as well as a recovery mechanism. Virtual Router Redundancy Protocol and Gateway Load Balancing Protocol are derivatives of HSRP providing additional Layer 3 redundancy features such as load balancing. High Availability is also accomplished by implementing a combination of device, link or hardware component redundancy at strategic points in the network. Optimal fault tolerance is provided by redundant Supervisor Engines in Multi Layer switches that also host a variety of failover services in software. Another Cisco High Availability feature is Single Router Mode which allows failover to a second MSFC.