GLBP

Gateway Load Balance Protocol is cisco proprietary protocol which gives a very efficient solution such as HSRP in addition to load balancing capability within a single GLBP group.

GLBP Operation
Active Virtual Gateway (AVG): response to ARP requests from hosts and assigns virtual MAC address to members of the GLBP group

Active Virtual Forwarder (AVF): A member of a GLBP group that discovers an Active Virtual Gateway AVG based on Hello messages, and learns its virtual MAC address from that AVG

Configure GLBP
glbp                    Gateway Load Balancing Protocol interface commands

R1(config-if)#glbp 10 ip 10.1.1.1
R1(config-if)#glbp 10 priority 110

R2#show glbp 
FastEthernet0/1 - Group 10
  State is Active
    2 state changes, last state change 00:05:36
  Virtual IP address is 10.1.1.1
  Hello time 3 sec, hold time 10 sec
    Next hello sent in 2.748 secs
  Redirect time 600 sec, forwarder time-out 14400 sec
  Preemption enabled, min delay 0 sec
  Active is local
  Standby is unknown
  Priority 100 (default)
  Weighting 100 (default 100), thresholds: lower 1, upper 100
  Load balancing: round-robin
  There are 2 forwarders (2 active)
  Forwarder 1
    State is Active
      1 state change, last state change 00:05:36
    MAC address is 0007.b400.0a01 (learnt)
    Owner ID is c004.809c.0001
    Redirection enabled, 253.616 sec remaining (maximum 600 sec)
    Time to live: 14053.612 sec (maximum 14400 sec)
    Preemption enabled, min delay 30 sec
    Active is local, weighting 100
    Arp replies sent: 1
  Forwarder 2
    State is Active
      1 state change, last state change 00:11:23
    MAC address is 0007.b400.0a02 (default)
    Owner ID is c002.1640.0001
    Redirection enabled
    Preemption enabled, min delay 30 sec
    Active is local, weighting 100

    Arp replies sent: 1