Moving around to plug/unplug a console cable from one to another is tired every time you want to configure/access different device. The solution to this problem is purchasing and configuring an Access Server.
Remote labs from Internetwork Expert also use an Access Server for the labs at racks.internetworkexpert.com.
If the Async port is serial like 2511's picture below, you will need a special octal cable CAB-OCTAL-ASYNC Cable. But if the Access Server Async ports are in RJ-45, you will only need a basic UTP RJ-45-to-RJ-45 rollover cable.
Once you've got your AS and the appropriate cable, you're ready to configure your AS. Below is the example diagram on how to connect the AS with the devices, and then you will connect one of the RJ-45 connectors to the console port of each one of your devices that has console port. If you're using an octal cable, make sure to note the number that's on the cable itself right below the connector, because that's very important.
In the above example, we have an Access Server, 2 routers, 1 switch, and 1 ASA.
Router 1 (R1) will be plugged using 1st cable and it will be using port 2001, 2nd cable will be port 2002, etc.
Basically we only need to configure a loopback interface, an an ip host name and port that point to the loopback address. The basic configuration will be like this:
hostname ASThere are two ways to connect to devices attached to an access server, you can terminate your exec session on the access server itself (one terminal window for all sessions), or you can terminate your exec session on the device connected to the access server (one terminal window for each session).
ip host ASA 2004 22.214.171.124
ip host S1 2003 126.96.36.199
ip host R2 2002 188.8.131.52
ip host R1 2001 184.108.40.206
ip address 220.127.116.11 255.255.255.255
no ip directed-broadcast
When you terminate your exec session on the access server you then “reverse telnet” to the individual devices connected to the access server. Normally to do this you first login to the access server and then issue the “show hosts” command to see the host mappings. Next, reverse telnet to them by typing the hostname and pressing enter. To get back to the access server issue the escape sequence CTRL-SHIFT-6-X. To do so hold ctrl and shift, hit 6, release all keys, then hit X. From the access server you can then open new connections or resume connections that you already have open.
When you terminate your exec session on the device connected to the access server, i.e. by telnetting to the access server at port 2001, you cannot issue the escape sequence to reconnect to the access server. In this situation you would open multiple terminal windows if you wanted to connect to multiple devices.In my office lab, I made it similar to internetwork expert racks lab. Using login local, and have multiple user plus a menu.
For more information watch this class-on-demand video on using an Access Server.