Which First Hop Redundancy Protocol optimizes default-gateway bandwidth usage across multiple devices?

GLBP (Gateway Load Balancing Protocol) is a Cisco proprietary FHRP that optimizes bandwidth usage by allowing multiple routers to act as a single virtual gateway, with each router actively forwarding traffic for a subset of clients. This load-balances traffic across the available gateways. LACP (Link Aggregation Control Protocol) is used for bundling multiple physical links into a single logical link, not for FHRP. HSRP (Hot Standby Router Protocol) and VRRP (Virtual Router Redundancy Protocol) are FHRPs that provide redundancy but typically operate in an active/standby or active/passive mode, meaning only one router is actively forwarding traffic for the virtual gateway at any given time, thus not optimizing bandwidth usage across multiple devices in the same way GLBP does.