Which protocol is a Cisco-proprietary protocol for load-balancing routers?

Gateway Load Balancing Protocol (GLBP) is a Cisco-proprietary protocol that supports redundancy and per-subnet load balancing. Proxy ARP is not considered an FHRP but is used in conjunction with FHRPs as a helper protocol. Virtual Router Redundancy Protocol (VRRP) is an IEEE open standard that is supported freely on many router products. Hot Standby Router Protocol (HSRP) is also a Cisco-proprietary FHRP for highly available gateways, but it does not support load balancing.