GLBP elects one AVG (Active Virtual Gateway) for each group.
Other group members act as backup in case of AVG failure.
Each AVF assumes responsibility for forwarding packets sent to its virtual MAC address.
By default, GLBP routers use the local multicast address 224.0.0.102 to send hello packets to their peers every 3 seconds over UDP 3222 (source and destination).
Cisco implemented IPv6 support for GLBP in IOS release 12.2(33)SXI.