High Availability

HSRP

Virtual Mac address 0000.0c70.ACxx where xx is the HSRP group number in hexadecimal

HSRP States

  • Initial – begin the HSRP process
  • Standby – waiting to become the active router
  • Learn – waiting to hear from the active router
  • Active – currently forwarding packets
  • Listen – listening for hellos from active and standby routers
  • Speak – takes part in election for active or standby or have just been preempted

Default Hello is 3 sec and holdtimer is 10 sec

HSRP v2 allows for 4095 groups, allows for matching group with vlan

VRRP

IP address can be virtual or actual IP address of the router

Highest priority router after a failure becomes the active router. Priority is between 1-255, default of 100.

Master fails → Advertises a priority of 0 → forces an election, without waiting for holddown to expire

Hello timer of 1 sec, holddown timer of 3 secs

GLBP

  • Default of per host round robin load balancing
  • Uses virtual mac address to respond to arp requests
  • Elects an Active Virtual Gateway (AVG) to manage load balancing and respond to ARP’s
  • AVG assigns virtual mac addresses to other GLBP routers and in turn hosts to the routers
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