When deploying a new network that includes both Cisco and third-party network devices, which redundancy protocol avoids the interruption of network traffic if the default gateway router fails?

VRRP (Virtual Router Redundancy Protocol) is an open-standard First Hop Redundancy Protocol (FHRP) defined by RFCs, making it compatible with devices from multiple vendors. It provides gateway redundancy by allowing a group of routers to share a single virtual IP and MAC address, with one active and others in standby, taking over if the active fails.

FHRP (First Hop Redundancy Protocol) is a category, not a specific protocol, so it doesn't inherently guarantee cross-vendor compatibility.

GLBP (Gateway Load Balancing Protocol) is a Cisco proprietary protocol and therefore would not be suitable for interoperability with third-party network devices.

HSRP (Hot Standby Router Protocol) is a Cisco proprietary protocol, which limits its use in environments with non-Cisco network devices.