Important facts about GLBP:

GLBP Group

• GLBP routers form a virtual group identified by a group number.
• Each GLBP group has a unique group identifier and a series of shared virtual IP addresses.

Router Roles

• In GLBP, multiple routers can take on the role of active virtual forwarder (AVF), which is responsible for routing traffic for a specific virtual IP address.
• All routers in the GLBP group can be active simultaneously, and each responds to ARP requests for different virtual IP addresses.

Load Distribution

• GLBP uses a loading algorithm to evenly distribute traffic among routers in the group.
• The algorithm is based on setting priorities and assigning load ratios to each router.

AVF election

• Similar to HSRP and VRRP, GLBP uses priority to choose the active router for a specific virtual IP address.
• A router's IP address can also be used to break the tie in case of a priority tie.

State Monitoring

• GLBP routers also use Hello packets to monitor the status of other routers in the group and detect failures.

Basic Configuration

• Configuring GLBP involves assigning a group number, a virtual IP address, and configuring the priority and load ratio on each interface of the routers involved.

GLBP is especially useful in environments where you want to take full advantage of the capacity of multiple routers and distribute the load evenly to improve network performance.

Comparison chart

This table provides a general comparison of the key features of HSRP, VRRP, and GLBP. Choosing between these protocols will depend on your specific network requirements, interoperability with other network devices, and the need for additional features such as load balancing.

Botton line

In the networking space, router redundancy protocols such as HSRP, VRRP, and GLBP play a crucial role in ensuring the availability and reliability of services. HSRP, developed by Cisco, lays the foundation by allowing multiple routers to work as a group, ensuring a smooth transition between active and standby devices in the event of failures.

VRRP, an IETF standard, shares similar goals but promotes interoperability between devices from different manufacturers. For its part, GLBP, also from Cisco, goes further by not only providing redundancy, but also balancing the traffic load between active routers, thus improving network efficiency.

The choice between these protocols will depend on the specific infrastructure and particular requirements of each network.