HSRP and VRRP have one router actively forwarding for the virtual IP while the others sit idle. GLBP (Gateway Load Balancing Protocol) is different - it can use ALL routers in the group simultaneously. One router is the Active Virtual Gateway (AVG), responsible for answering ARP requests, but it hands out DIFFERENT virtual MACs to different hosts. Each host then sends traffic to a different Active Virtual Forwarder (AVF) - effectively load-balancing host traffic across multiple routers. This lab configures GLBP between R1 and R2 on the base topology.
What you will learn
- The GLBP architecture: AVG, AVF, the role split
- How GLBP load-balances at the ARP layer (different hosts get different MACs)
- The three load-balancing methods: round-robin, weighted, host-dependent
- Why GLBP is Cisco-only and what alternatives exist (multi-chassis link aggregation)
What this lab does NOT cover
- GLBP forwarder tracking with object trackers
- GLBP authentication
Topology
Download the CCNA Base Topology .yaml
The PingLabz CCNA Base Topology - 3 iol-xe routers + 1 alpine + 1 ioll2-xe switch.
The roles
| Role | Responsibility |
|---|---|
| AVG (Active Virtual Gateway) | Answers ARP requests for the virtual IP. Decides which forwarder's MAC to hand out for each requesting host. |
| AVF (Active Virtual Forwarder) | Forwards traffic sent to a specific virtual MAC. Up to four AVFs per group. |
| Standby AVG | Takes over AVG role if the current AVG fails. |
