Accessing Remote Device Using Telnet or SSH

The hostname is used in CLI prompts. If the hostname is not explicitly configured, a router uses the factory-assigned default hostname "Router." A switch has a factory-assigned default hostname, "Switch." Imagine if an internetwork had several routers that were all named with the default name "Router." This would create considerable confusion during network configuration and maintenance.

When accessing a remote device using Telnet or SSH, it is important to have confirmation that an attachment has been made to the proper device. If all devices were left with their default names, we could not identify that the proper device is connected.

By choosing and documenting names wisely, it is easier to remember, discuss, and identify network devices. To name devices in a consistent and useful way requires the establishment of a naming convention that spans the company or, at least, the location. It is a good practice to create the naming convention at the same time as the addressing scheme to allow for continuity within the organization.

Some guidelines for naming conventions are that names should:
Start with a letter
Not contain a space
End with a letter or digit
Have characters of only letters, digits, and dashes
Be 63 characters or fewer

The hostnames used in the device IOS preserve capitalization and lower case characters. Therefore, it allows you to capitalize a name as you ordinarily would. This contrasts with most Internet naming schemes, where uppercase and lowercase characters are treated identically. RFC 1178 provides some of the rules that can be used as a reference for device naming.

As part of the device configuration, a unique hostname should be configured for each device.

Note: Device host names are only used by administrators when they use the CLI to configure and monitor devices. Unless configured to do so, the devices themselves do not use these names when they discover each other and interoperate.

Applying Names - an Example

Let's use an example of three routers connected together in a network spanning three different cities (Atlanta, Phoenix, and Corpus) as shown in the figure.

To create a naming convention for routers, take into consideration the location and the purpose of the devices. Ask yourself questions such as these: Will these routers be part of an organization's headquarters? Does each router have a different purpose? For example, is the Atlanta router a primary junction point in the network or is it one junction in a chain?

In this example, we will identify each router as a branch headquarters for each city. The names could be AtlantaHQ, PhoenixHQ, and CorpusHQ. Had each router been a junction in a successive chain, the names could be AtlantaJunction1, PhoenixJunction2, and CorpusJunction3.

In the network documentation, we would include these names, and the reasons for choosing them, to ensure continuity in our naming convention as devices are added.

Once the naming convention has been identified, the next step is to apply the names to the router using the CLI. This example will walk us through the naming of the Atlanta router.

Accessing Remote Device Using Telnet or SSH
Accessing Remote Device Using Telnet or SSH
Accessing Remote Device Using Telnet or SSH
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