Written By James Ravenscroft
It can be a real headache to configure practice labs using a single console cable. An alternative to this is purchasing and configuring a dedicated Cisco access server such as the 2509 or 2511. This is beneficial since you will more than likely run across these types of devices at some point in a production environment, but assuming you don't want to spend the $$$, you can set up a Ubuntu (or other Linux) box to function as an access server using materials you may already have on hand (or which are inexpensive to purchase). I have outlined the steps below using Ubuntu 10.4:
1) Get a USB 2.0 hub, USB-to-serial adapters (something like this should do: http://www.usbgear.com/computer_cable_details.cfm?sku=765288&cats=199&catid=199%2C601%2C461) and Cisco-compatible serial rollover cables.
2) Connect the rollover cables to your USB-to-serial adapters then connect the adapters to the USB hub. Connect the USB hub to a USB port on the Ubuntu box and power it up or reboot. Check under /dev for ttyUSB devices- there should be one listed for each of the USB-to-serial adapters (I have two currently connected to my 4-port USB hub). If these are not present, try connecting the USB-to-serial adapters directly to your USB ports temporarily.
user@Ubuntu64:~$ ls -al /dev | grep 'ttyUSB'
crw-rw---- 1 root dialout 188, 0 2011-01-29 12:43 ttyUSB0
crw-rw---- 1 root dialout 188, 1 2011-01-29 12:43 ttyUSB1
3) Install and configure minicom, a command-line modem/serial communication program.
$sudo apt-get install minicom
$sudo minicom -s
Serial port setup, option A, change serial port listed to ttyUSB<x> where <x> is the number of the serial port you want to configure, then option E, change to 9600 8N1 (C, Q, Enter); at main screen, select "Save setup as.." and name the configuration to something easy to remember/type later
Once you have saved all your configurations, navigate to /etc/minicom. Each of your configurations should be present as minirc.<configname> where <configname> is the name of each of the configs you entered and saved earlier. Open the files in a text editor to see the configuration which should look like this:
# Machine-generated file - use "minicom -s" to change parameters.
pu port /dev/ttyUSB0
pu baudrate 9600
pu bits 8
pu parity N
pu stopbits 1
4) Open a terminal session on your Ubuntu box and launch Minicom ($sudo minicom <configname>). Power up a Cisco device and connect it to each of your cables until you see terminal output from your Cisco device scrolling by in the terminal window. Label the connected cable so that you know which serial-to-USB connection is being used to connect to a given piece of equipment in the future. Do this for each of your minicom configurations until all of your cables are labeled.
Congratulations! You can now connect to your Cisco gear via console cables through your Ubuntu box. Of course it is entirely up to you to ensure that your Ubuntu box is properly configured and secured prior to doing this or anything else on it and you should commit to keeping it properly configured and secure in the future. If you are unwilling or unable to do this, you will want to consider renting live rack time using actual Cisco gear through a site such as http://www.howtonetwork.net or the community rack on http://packetlife.net/ to practice instead.
