• Virtual IP address and virtual MAC are active on the HSRP Active router.
  • 3 sec hello, 10 sec dead
  • – V1
  • – V2
  • Virtual MAC of 0000.0C07.ACxx (v1)
  • Virtual MAC of 0000.0c9f.fxxx for IPv4 (v2) and 0005.73a0.0xxx for IPv6 (v2)
  • Port UDP 1985 for IPv4
  • Port UDP 2029  for IPv6 
  • Clear-text & MD5 auth
  • MHSRP (administrative LB)
  • Only 1 standby, highest IP preemts standby.


  • IP protocol number 112; TTL 255 – MUST
  • 1 sec hello, 3 sec dead
  • Virtual MAC of 0000.5E00.01xx
  • Preempts by default
  • Group IP address is the interface IP address of one of routers (prio for the router will be 255)
  • Higest IP preempts; more than 1 standby
  • The priority value zero (0) has special meaning indicating that the current Master has stopped participating in VRRP. Backups quickly transition to master.


  • UDP 3222
  • 3 sec hello, 10 sec dead
  • 0007.B400.xxyy , where xx is the GLBP group number and yy is a different number for each router (01, 02, 03, or 04).
  • 1024 GLBP groups per physical interface and up to four AVF per GLBP group
  • If multiple gateways have the same priority (1-255), the gateway with the highest real IP address becomes the AVG; standby AVG election – same principle.
  • The Redirect timer (600 sec) determines how long will AVG continue to respond to ARP requests with the virtual MAC of the failed AVF. The Secondary Hold  (4 hours, 14400 sec) timer sets the amount of time the backup AVF will continue to accept packet for the virtual MAC address taken from the failed AVF.

Leave a Reply