Contents
What are FHRPs? – Meaning and Types of First Hop Redundancy Protocol
First Hop Redundancy Protocol (FHRP) is a network protocol that provides redundancy and fault tolerance for network gateways or routers. It ensures high availability and minimizes network downtime by allowing multiple routers to work together as a virtual router.
FHRPs are used in networks where a single router acts as the default gateway for the connected devices. In the event of a failure or outage of the primary router, the FHRP enables the backup router(s) to take over seamlessly, ensuring uninterrupted network connectivity.
There are several types of FHRPs that are commonly used in network infrastructure. Let’s take a closer look at each type:
Hot Standby Router Protocol (HSRP)
Hot Standby Router Protocol (HSRP) is a Cisco proprietary FHRP. It provides redundancy by creating a virtual IP address and virtual MAC address for a group of routers. One router is elected as the active router, while the others are in standby mode. The active router handles the network traffic, and the standby routers are ready to take over if the active router fails.
HSRP works by periodically exchanging Hello messages between the routers to determine the active and standby roles. If the active router fails, one of the standby routers takes over the virtual IP address, ensuring continuity of network services.
Virtual Router Redundancy Protocol (VRRP)
Virtual Router Redundancy Protocol (VRRP) is a standard FHRP defined in the RFC 5798. Like HSRP, VRRP creates a virtual IP address and virtual MAC address for a group of routers. However, VRRP is not proprietary to a specific vendor and is supported by multiple network devices.
VRRP also uses an active and standby router configuration, with the active router handling the network traffic. It uses periodic advertisements to communicate the router’s state within the VRRP group. If the active router fails, the backup routers elect a new active router to ensure uninterrupted network connectivity.
Gateway Load Balancing Protocol (GLBP)
Gateway Load Balancing Protocol (GLBP) is another Cisco proprietary FHRP that provides load balancing along with redundancy. GLBP enables multiple routers to share the network traffic load by distributing it across the available routers.
GLBP works by designating one router as the active virtual gateway (AVG) and the others as active virtual forwarders (AVFs). The AVG handles ARP (Address Resolution Protocol) requests and replies with the virtual MAC address of one of the AVFs. This load balancing mechanism distributes the traffic among the AVFs.
If the AVG fails, another router in the group takes over as the new AVG. GLBP also allows for active/active redundancy, where multiple routers in a group can forward packets at the same time.
In conclusion, FHRPs like HSRP, VRRP, and GLBP ensure network availability and redundancy by enabling multiple routers to work together seamlessly. Depending on your network infrastructure and requirements, choosing the right FHRP can enhance the reliability and performance of your network.
Reference Articles
Read also
[Google Chrome] The definitive solution for right-click translations that no longer come up.