What is an Access Server or Terminal Server used for?

Components of a Cisco Access Server

To configure a Router as an Access Server we first have to make sure that we the following two components

• An Asynchronous Serial Interface either built into the Cisco router or in an interface module.

Figure 1 shows a Cisco 2500 Series Router with two Asynchronous Serial Interface (SCSI II 68-pin)
Figure 2 shows a NM-32A/S Module that can be used in any supported Cisco Modular Router.

Figure 1

Figure 2

• CAB-OCTAL-ASYNC: This cable provides eight RJ-45 rolled cable async ports which can be connected to console ports of devices that need to be managed. The figure below shows an octal cable, one end of the cable that has 68-Pin connector is connected to async interface, the other end provides 8 RJ-45 cables to connect to console ports. 

Configuring a Cisco Access Server

We will use Cisco 3640 with NM-32A/S as an Access Server in this article. The diagram below shows our network setup.

We are setting up an Access Server to access console ports of eight Cisco devices (two Cisco Switches and six Cisco Routers). We can also access these devices from anywhere over the Internet via Virtual Private Network (VPN) connection to Cisco ASA/PIX Firewall and then access the Cisco Access Server. The Configuration of Firewall is not in the scope of this article.

The most basic configuration is to define the TTY lines and allow telnet input into these lines.

Access-Server(config)#line 33 64
Access-Server(config)#transport input telnet
Access-Server(config-line)#no exec

Note – Please Refer to How Async Lines are Numbered on 3600 series Router document on Cisco Website in order to understand Async Line Numbering.

When we need console access to any device all we have to do is telnet to the line of that device. For example, our first line is connected to a Cisco 2800 Series Router. From our Personal Computer we can access this by using the following command from command prompt – telnet