Cisco IOS: First Hop Redundancy Protocols (Part 2) - VRRP

Introduction

In the previous part of this 3 part series, we looked at HSRP. Today we will look at VRRP, its features and how to configure it within Cisco IOS.

VRRP vs HSRP

VRRP is extremely similar to HSRP. However, unlike HSRP, VRRP is not Cisco proprietary.
Let us look at the differences between HSRP and VRRP:

Table 1 : HSRP vs VRRP.^[1]

Configuration

Now, we will configure VRRP, based on the diagram below. Furthermore, our VIP will be 10.0.128.10.

Figure 1 : Topology.

Initial Setup

R1

R1(config)#interface GigabitEthernet0/2
R1(config-if)# vrrp 10 ip 10.0.128.10
R1(config-if)# vrrp 10 priority 110

R2

R2(config)# interface GigabitEthernet0/2
R2(config-if)# vrrp 10 ip 10.0.128.10

Verification

R1#show vrrp br 
Interface          Grp Pri Time  Own Pre State   Master addr     Group addr
Gi0/2              10  110 3570       Y  Master  10.0.128.1      10.0.128.10  

Interface Tracking

Next, we will configure VRRP to track an interface, i.e the uplink interface (gi0/1). If the interface goes down then the VRRP priority will be decremented, in turn resulting in R2's priority to be higher and failover to occur.

R1

R1(config)# track 1 interface gi0/1 line-protocol 
R1(config)#int gi0/2
R1(config-if)#vrrp 10 track 1 decrement 20

Verification

To confirm that this is configured correctly, we issue a shutdown on gi0/1.
We see the following output,

*May  7 05:19:46.809: %VRRP-6-STATECHANGE: Gi0/2 Grp 10 state Master -> Backup

Now, if we run a show VRRP we can see the expected output,

R1(config)# do show vrrp
GigabitEthernet0/2 - Group 10 
  State is Backup  
  Virtual IP address is 10.0.128.10
  Virtual MAC address is 0000.5e00.010a
  Advertisement interval is 1.000 sec
  Preemption enabled
  *Priority is 90  (cfgd 110)*
    *Track object 1 state Down decrement 20*
  Master Router is 10.0.128.2, priority is 100 
  Master Advertisement interval is 1.000 sec
  Master Down interval is 3.570 sec (expires in 3.243 sec)

Authentication

As the final step, we will configure authentication. This is a simple process of adding the VRRP authentication commands to each device and then verifying.

R1/R2

R1/R2(config-if)# vrrp 10 authentication md5 key-string VRRPPW

Verification

R1# show vrrp
GigabitEthernet0/2 - Group 10 
  State is Master  
  Virtual IP address is 10.0.128.10
  Virtual MAC address is 0000.5e00.010a
  Advertisement interval is 1.000 sec
  Preemption enabled
  Priority is 110 
    Track object 1 state Up decrement 20
  *Authentication MD5, key-string*
  Master Router is 10.0.128.1 (local), priority is 110 
  Master Advertisement interval is 1.000 sec
  Master Down interval is 3.570 sec

References