VRRP (Virtual Router Redundancy Protocol)

VRRP (Virtual Router Redundancy Protocol) is very similar to HSRP (Hot Standby Routing Protocol) and can be used to create a virtual gateway. If you don’t know why we use virtual gateways then I suggest to read my Introduction to virtual gateways first. Also make sure you check the HSRP lesson first since many of the things I describe there also apply to VRRP.

VRRP is very similar to HSRP; if you understood HSRP you’ll have no trouble with VRRP which is a standard protocol defined by the IETF in RFC 3768. Configuration-wise it’s pretty much the same but there are a couple of differences.

Let’s start with an overview:

  HSRP VRRP
Protocol Cisco proprietary IETF – RFC 3768
Number of groups 16 groups maximum 255 groups maximum
Active/Standby 1 active, 1 standby and multiple candidates. 1 active and several backups.
Virtual IP Address Different from real IP addresses on interfaces Can be the same as the real IP address on an interface.
Multicast address 224.0.0.2 224.0.0.18
Tracking Interfaces or Objects Objects
Timers Hello timer 3 seconds, hold time 10 seconds. Hello timer 1 second, hold time 3 seconds.
Authentication Supported Not supported in RFC 3768

As you can see there are a number of differences between HSRP and VRRP. Nothing too fancy however. HSRP is a cisco proprietary protocol so you can only use it between Cisco devices.

Let’s see if we can configure it…

Configuration

This is the topology that I will use:

virtual gateway example topology

SW1 and SW2 are multilayer switches and their interfaces are configured as routed ports. We will create a virtual gateway using VRRP on the interfaces facing SW3:

SW1(config)#interface fa0/17
SW1(config-if)#vrrp 1 ip 192.168.1.3
SW1(config-if)#vrrp 1 priority 150
SW1(config-if)#vrrp 1 authentication md5 key-string mykey
SW2(config-if)#interface fa0/19
SW2(config-if)#vrrp 1 ip 192.168.1.3
SW2(config-if)#vrrp 1 authentication md5 key-string mykey

Here’s an example how to configure VRRP. You can see the commands are pretty much the same but I didn’t type “standby” but vrrp. I have changed the priority on SW1 to 150 and I’ve enabled MD5 authentication on both switches.

SW1#
%VRRP-6-STATECHANGE: Fa0/17 Grp 1 state Init -> Backup
%VRRP-6-STATECHANGE: Fa0/17 Grp 1 state Backup -> Master
SW2#
%VRRP-6-STATECHANGE: Fa0/19 Grp 1 state Init -> Backup 
%VRRP-6-STATECHANGE: Fa0/19 Grp 1 state Backup -> Master 
%VRRP-6-STATECHANGE: Fa0/19 Grp 1 state Master -> Backup

You will see these messages pop-up in your console. VRRP uses different terminology than HSRP. SW1 has the best priority and will become the master router. SW2 will become a backup router. Let’s see what else we have:

SW1#show vrrp 
FastEthernet0/17 - Group 1  
  State is Master  
  Virtual IP address is 192.168.1.3
    Secondary Virtual IP address is 192.168.1.4
  Virtual MAC address is 0000.5e00.0101
  Advertisement interval is 1.000 sec
  Preemption enabled
  Priority is 150 
  Authentication MD5, key-string "mykey"
  Master Router is 192.168.1.1 (local), priority is 150 
  Master Advertisement interval is 1.000 sec
  Master Down interval is 3.414 sec
SW2#show vrrp 
FastEthernet0/19 - Group 1  
  State is Backup  
  Virtual IP address is 192.168.1.3
  Virtual MAC address is 0000.5e00.0101
  Advertisement interval is 1.000 sec
  Preemption enabled
  Priority is 100 
  Authentication MD5, key-string "mykey"
  Master Router is 192.168.1.1, priority is 150 
  Master Advertisement interval is 1.000 sec
  Master Down interval is 3.609 sec (expires in 3.065 sec)

Use show vrrp to verify your configuration. The output looks similar to HSRP; one of the differences is that VRRP uses another virtual MAC address:

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Forum Replies

  1. You write the best articles of how to configure these things.
    Well written, good job René! :slight_smile:

  2. Still how the computers uses both gateways in their configuration if we load balance between two groups?

    Veerender

  3. Hi Veerender,

    For example, if you have 100 computers then you configure 50 of them to use 192.168.1.3 and the other 50 to use 192.168.1.4.

    Rene

  4. Hi Rene
    I’m using for the lab Cisco Switches 3550 and 3750 as layer 3 switches, and those doesn’t seem to support VRRP or GLBP, what model are you using for this lab and the glbp lab, thank you and by the way, thank you for your last reply.

    regards
    Ramon

  5. Hi Ramon,

    The 3550 only supports HSRP while the 3750 supports HSRP + GLBP. I just checked my 3750 and this is the IOS image I am using:

    c3750-advipservicesk9-mz.122-46.SE.bin

    Funny thing is, I have a 3560 that runs the same IOS version but it only supports HSRP:

    c3560-advipservicesk9-mz.122-46.SE.bin

    Probably best to use some routers or GNS3 to test this.

    Rene

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