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GLBP

This is a Cisco proprietary FHRP. The v4 and v6 exist for IOS, but v6 is missing for IOS-XE.

Terms

GLBP

  • Gateway Load Balancing Protocol
  • Cisco Proprietary
  • Supports 4 active forwarding instances

AVG

  • Active Virtual Gateway
  • The AVG is responsible for answering incoming ARP for the VIP
  • Can reply with a different MAC addresses to load balance
  • Highest priority router is the AVG

AVF

  • Active Virtual Forwarder
  • Two states {Active, Listen}
  • All AVFs have their own mac and forwarding traffic destined towards that MAC
  • 4 max.

Details

  • Multicast
    • 224.0.0.102
  • UDP 3222
  • MD5 is supported
  • Default timers: 3s / 10s

Example

R1# show glbp brief
Interface   Grp  Fwd Pri State    Address         Active router   Standby router
Gi0/0       12   -   100 Active   192.168.12.12   local           192.168.12.2
Gi0/0       12   1   -   Active   0007.b400.0c01  local           -
Gi0/0       12   2   -   Listen   0007.b400.0c02  192.168.12.2    -

References

Cisco - Configuring GLBP

Solved: Re: ASR-1002X IPv6 GLBP - Cisco Community

Last Modified • Tuesday, June 9, 2026. 11:22 pm UTC+00:00 • Commit: 4b2315b