First Hop Resolution Protocols

HSRP, VRRP, and GLBP are all used to provide redundancy in a LAN environment. HSRP and VRRP create a virtual router with one active router and standby routers, while GLBP adds load balancing capabilities in addition to redundancy. HSRP and GLBP are Cisco proprietary protocols, while VRRP is an open standard protocol. The choice between these protocols depends on the specific requirements of the network and the equipment used.

HSRP (Hot Standby Router Protocol):

HSRP is a Cisco proprietary protocol.

1. It allows for the creation of a virtual router, with multiple physical routers participating in an HSRP group.
2. One router is elected as the active router, which handles traffic forwarding, while the others act as standby routers.
3. The active router sends periodic hello messages to the standby routers to ensure their availability.
4. In the event of the active router’s failure, one of the standby routers is elected as the new active router.
5. HSRP supports IPv4 and IPv6.

VRRP (Virtual Router Redundancy Protocol)

1. VRRP is an open standard protocol.
2. Similar to HSRP, VRRP allows for the creation of a virtual router, with multiple physical routers participating in a VRRP group.
3. One router is elected as the master router, responsible for traffic forwarding, while the others act as backup routers.
4. The master router sends periodic advertisements to the backup routers to maintain their availability.
5. If the master router fails, another backup router takes over as the new master router.
6. VRRP supports IPv4 and IPv6.

GLBP (Gateway Load Balancing Protocol)

1. GLBP is a Cisco proprietary protocol.
2. GLBP provides not only redundancy but also load balancing for outgoing traffic.
3. Multiple routers participate in a GLBP group, with one router acting as the active virtual gateway and the others as backup virtual gateways.
4. The active virtual gateway handles traffic forwarding and also assigns a virtual MAC address to each member router.
5. Hosts on the LAN segment use the virtual gateway’s virtual IP address as their default gateway.
6. GLBP distributes traffic among the backup virtual gateways using different load balancing methods.
7. If the active virtual gateway fails, another backup virtual gateway takes over as the new active gateway.
8. GLBP supports only IPv4.