VRRP — the open one

RFC 5798, IP protocol 112, multicast 224.0.0.18, virtual MAC 0000.5e00.01XX, advertisement every 1 s. Master/Backup instead of Active/Standby — and a real IP-owner concept: the device holding the IP can be priority 255. vrrp version 3 adds IPv6.

GLBP — the load-balancing one

Cisco, UDP 3222, 224.0.0.102. One virtual IP but multiple virtual MACs: the AVG answers ARP with a different MAC per host, each AVF forwards for its own MAC — several gateways active at once, no manual groups needed.

glbp 10 ip 10.10.10.254
glbp 10 load-balancing round-robin | weighted | host-dependent

When to use which: multivendor → VRRP; need active/active gateways without two FHRP groups → GLBP; otherwise HSRP’s boring reliability.