Terminology » Networking Basics » VRRP vs VRF: Understanding the Key Differences

VRRP vs VRF: Understanding the Key Differences

networking routing protocol vrrp vrf

This page compares VRRP vs VRF and mentions the difference between VRRP and VRF.

VRRP stands for Virtual Router Redundancy Protocol, and VRF stands for Virtual Routing Forwarding.

It also mentions how VRRP works.

VRRP - Virtual Router Redundancy Protocol

VRRP-Virtual Router Redundancy Protocol

As mentioned, VRRP is the short form of Virtual Router Redundancy Protocol. This protocol specifies an election protocol which dynamically assigns responsibility to a virtual router when another router fails on a LAN. The backup router takes responsibility for the failed master router on the LAN. This will help hosts connected on the same LAN segment to continue use of internet services on the other side of the routers.

In short, VRRP is an election protocol which provides redundancy to the routers installed in a LAN. Using VRRP protocol, a virtual IP address can be given either manually or using DHCP protocol as default. A virtual IP address is shared among the routers, with one router designed as the master router and the others are designed as backup routers. Basically using VRRP, a backup router can take over as gateway if the master router fails.

The VRRP (Virtual Router Redundancy Protocol) has been defined in RFC-2338 and RFC-5798.

VRRP protocol based devices work in following three states:

  • Initialize state: In this state, the device detects its own state based on received advertisement packets.
  • Master state: In this state, the device will send out advertisement packets.
  • Backup state: In this state, the device will listen to advertisements comparing its priority with the priority advertised in the packet.

A backup router will take over as master due to the following conditions:

  • The master router goes down due to some problem.
  • The network manager either shuts down the LAN interface or turns OFF master routing switch.

Following table mentions fields or terminologies associated in VRRP protocol which help understand how VRRP works.

VRRP TerminologyDescription
VRIDVirtual router Identifier, It can be assigned value from range 1 to 255 (decimal). There is no default value.
PriorityThe priority field is used by VRRP router in master election for the virtual router. The 255 value is used for router which owns IP addresses for virtual routers. 0 value is assigned to master to indicate it is releasing responsibility to backup router. The range from 1 to 254 is available for backup routers. The default value of backup router is 100 (decimal).
Virtual IP AddressThe virtual IP address must belong to the same subnet as real IP address configured on VRRP interface. The virtual router which has virtual IP address same as real IP address, is called IP address owner and default master router. Virtual IP Address of backup router is configured same as master router.
Virtual MAC AddressThe RFC3768 and RFC5768 specify 48 bit MAC address associated with VRRP virtual router. ARP protocol translation helps convert IPv4 or IPv6 address into this virtual mac address. It is used as source address in all periodic VRRP messages sent by Master router. Virtual router MAC address is defined as 00-00-5E-00-01-{VRID} in hex notation. Here VRID is VRRP Virtual Router Identifier. Hence we can have total of 255 VRRP routers on single network.
Authentication TypeIt is 8 bit unsigned integer. It identifies authentication method utilized. Value of 0 indicates no authentication used.
VersionIndicates VRRP protocol version.

VRF - Virtual Routing Forwarding

As mentioned, VRF is the short form of Virtual Routing and Forwarding. It is an IP technology which allows more than one instances of routing tables to co-exist on same router simultaneously.

As routing instances are independent of one another, it allows reuse of same or over-lapping IP addresses without any conflicting issues. As there is one routing table available for each of the VRF instances, a VRF capable router functions as a group of multiple virtual routers on the same physical router.

VRF (Virtual Routing and Forwarding) are developed to support BGP (Border Gateway Protocol) and MPLS (Multiprotocol Label Switching) protocols.