How does HSRP provide first hop redundancy?
Click on the arrows to vote for the correct answerA. B. C. D.
HSRP (Hot Standby Router Protocol) is a Cisco proprietary protocol that provides redundancy for IP networks, specifically for the first hop of a host on a LAN. It works by allowing multiple routers to share a virtual IP address and a virtual MAC address that represent a single virtual router. HSRP ensures that the virtual router is always available to forward traffic in case of a failure of the active router.
Answer B is correct. HSRP provides first hop redundancy by using a shared virtual MAC and virtual IP address that are assigned to a group of routers that serve as the default gateway for hosts on a LAN. This group of routers is referred to as an HSRP group.
The routers in the HSRP group communicate with each other using multicast messages to elect an active router and a standby router. The active router is responsible for forwarding traffic to the virtual IP address, while the standby router monitors the active router's status and takes over if it fails.
When a host sends a packet to a destination, it uses the virtual IP address as the destination IP address. The source MAC address of the packet is the MAC address of the sending host, while the destination MAC address is the virtual MAC address of the HSRP group. The router that is currently the active router for the HSRP group receives the packet, forwards it to the destination, and updates its ARP cache with the MAC address of the sending host.
HSRP provides first hop redundancy by ensuring that there is always an active router available to forward traffic. If the active router fails, the standby router takes over as the active router and begins forwarding traffic to the virtual IP address. This failover process is transparent to the hosts on the LAN, which continue to use the same virtual IP address and default gateway.
In summary, HSRP provides first hop redundancy by using a shared virtual MAC and virtual IP address that represent a group of routers serving as the default gateway for hosts on a LAN. It allows for transparent failover of the active router in case of a failure, ensuring that traffic can always be forwarded to the virtual IP address.