Configuring Router Interface Descriptions on a Cisco Router

If someone were to look at your router’s configuration, could they understand what the real purpose of the network connections were, who they connect to, and what to do if the interface is down? If you answered no, then you need to look at using router interface descriptions.

What is a router interface description?

Router interface descriptions are description commands that network administrators configure on each interface of a router. With these commands, the administrator can enter whatever pertinent information he wants to, about that interface. This can be very useful for the original administrator that configured the interface. Or this can be valuable to any other administrator that has to try to troubleshoot or reconfigure the interface later. For example, you could put the following command on your router’s interface:

description T1 circuit to Internet – Sprint Circuit ID QVX.123.098.765.DAX – Tech Support 800-555-1234

By using this command, I have described what the circuit’s purpose was, the Circuit ID, the provider, and the tech support phone number.

By doing this, the next time I look at the router, I have all the important troubleshooting information I need, right at my fingertips.

Uses of a router interface description

The recommended uses for the router interface description command are:

• Identifying the interface

• Noting who to call if the interface is down

• Documenting the circuit information for that connection

• In general, using the description for a “notes” field

I have even used the description field to notate what the current IP address was on an interface before I changed the IP address. That way, I have documentation, on the router’s interface, what the previous configuration was.

Keep in mind that while we are calling this field a “router” interface description, the description command works on Cisco IOS switches and PIX firewalls as well.

Sample configuration of a router interface configuration

To apply a description on your router’s interface, use the following steps:

1. Move to global configuration mode, like this:

​router# config t
router(config)#

2. Move to interface configuration mode. In our example, let’s assign an a description to the Serial 0/0 interface:

​router(config)# interface serial 0/0
router(config-if)#

3. Use the description command with the description you define for this interface. Here is an example:

​router(config-if)# description T1 circuit to Internet – Sprint Circuit ID QVX.123.098.765.DAX – Tech Support 800-555-1234

4. To view the interface’s description, press Ctrl-Z to exit back to privileged mode then type:

​router# show run interface serial 0/0
interface Serial 0/0
description T1 circuit to Internet – Sprint Circuit ID QVX.123.098.765.DAX – Tech Support 800-555-1234
ip address 1.1.1.1 255.255.255.0

In the graphic below, you can actually see how it is done:

Article Summary

What you need to take home from this article is that the Cisco IOS description command can be used on Cisco Routers, Switches, and PIX Firewalls to create custom descriptions for every interface on those devices. These custom descriptions can be used to better document and more quickly troubleshoot your network.

FAQs

How does Cisco’s description command tie into network‑monitoring tools?

The description command can be integrated with various network monitoring tools, allowing administrators to automatically pull interface descriptions into their monitoring dashboards, making it easier to track and manage network segments across multiple platforms.

Can I use special characters in CISCO description commands?

While the CISCO description command allows for most ASCII characters, it’s recommended to avoid special characters like quotes, backslashes, or angle brackets as they may cause parsing issues. Stick to alphanumeric characters, hyphens, and underscores for optimal compatibility.

What happens to CISCO settings during a router reload?

CISCO configurations are stored in the running configuration and startup configuration (if saved), ensuring they persist through router reloads and power cycles, maintaining your documentation across system restarts.

Is there a character limit for CISCO description commands?

The CISCO description command has a maximum length of 240 characters in most recent IOS versions, though older versions may have shorter limits. It’s best practice to keep descriptions concise while including essential information.

Can I use the description command feature in configuration templates?

The CISCO description command can be incorporated into configuration templates and scripts, allowing for automated deployment of standardized interface descriptions across multiple devices in your network infrastructure.