Cisco Virtual Router Redundancy Protocol (VRRP) Configuration

The configuration of a basic Virtual Router Redundancy Protocol (VRRP) implementation is not all that complex, and resembles a lot the configuration of Cisco’s Hot Standby Router Protocol (HSRP) if the reader is more familiar with that protocol. This section first covers the configuration process steps and commands that are used to perform a basic VRRP configuration. An example is then given on how these steps can be used to configure VRRP in a sample networking topology.

VRRP Simple Configuration Steps

Only a few commands are required to get VRRP up and working. Table 1 features these commands and a few other common commands that are used to modify the default behavior of VRRP.

Table 1 – VRRP Configuration Commands

VRRP Simple Example

Because often it is easier to see the complete application of a subject, this section goes over the configuration of VRRP between two devices in a sample network. Figure 1 displays the topology that will be used; Table 2 and 3 will then display the commands required on both R1 and R2.

Figure 1 VRRP example topology

The configuration will perform the following:

• Configure the IP addresses 10.10.20.1/30 (R1) and 10.10.20.2/30(R2) on their Fa0/1 interfaces.
• Configure the IP addresses 172.16.1.1/24 (R1) and 172.16.2.1 (R2) on their Fa0/0 interfaces.
• Configure VRRP between R1 and R2 using the IP addresses 10.10.10.1/24 (R1) and 10.10.10.2/24(R2) and a virtual IP address of 10.10.10.5 on their Fa1/0 interfaces.
• Configure R1 with a VRRP priority of 140.

Table 2 – R1 Simple Example Configuration

Table 3 – R2 Simple Example Configuration

VRRP Complex Configuration Steps

As with most features, a number of different optional features may or may not be useful depending on the specific implementation situation. This section reviews the additional commands that can be configured to take advantage of these additional features (Table 4), and then covers another example using these features.

Table 4 – VRRP Complex Configuration Commands

VRRP Complex Example

This section covers an example using both VRRP MD5 authentication (using a basic key-string) and VRRP object tracking. For the object tracking configuration, R1 will be configured to monitor the line protocol state of its own fa0/0 interface. If it goes down, then its VRRP priority will be lowered by 50; R2 will be configured the same using its fa0/0 interface. The examples in Tables 5 and 6 build upon the simple VRRP example shown earlier in Table 4.

Table 5 – R1 Complex Example Configuration Addition

Table 6 – R2 Complex Example Configuration Addition

Summary

One thing that has been rather consistent over the last 20 years is that most LAN segments all include a single gateway that is used by everyone on that segment. While in past, this may not have been that big of a deal, but in modern networks, almost everyone is actively using the network to do normal tasks and often this involves access to parts of the network that are not local to a host’s machine. Because of this, the implementation of FHRPs has become more common in these types of network environments.

Knowledge of these options is an important part of the education of any LAN administrator or engineer, and should be known as part of all Cisco routing and switching certification tracks. I hope that this article enables you to have a better understanding of how the different configuration commands can be put together to obtain an expected, well thought-out solution to this common design issue.