Setting up my Cisco Lab Pt 1: Connecting to the Console

I bought some used Cisco gear off ebay to set up a small home networking lab. For the CCNA, I used Packet Tracer, so it's great to get my hands on some actual gear for the first time. Here's the gear list:

• Catalyst 2950 24-port

• Catalyst 2960 8-port

• Catalyst 3560 24-port (Layer 3)

• 1841 ISR Router

The first step was connecting to each of them with a console cable and powering them up to make sure they worked. That's the subject of this post.

To connect to the console, I used my (very old) Dell Latitude d410 laptop, which had no OS when I bought it. I installed 32-bit Lubuntu; it's perfectly adequate for these purposes.

This video explains the steps for connecting to the console via Linux; I'll summarize those instructions here. The commands may be different depending on your Linux distro; check out this post to see commands for distros other than Debian. Begin with neither power nor console cables connected to your devices.

At this point, your switch or router should still be OFF. First, install the program Minicom, which is a terminal emulator program. Open the command line and install Minicom with the command:

sudo apt install minicom

Next, clear the buffer. The 'dmesg' command in Linux is used to view device driver messages and other information from the Linux kernel. We'll clear it first to more easily identify the USB port ID we need:

sudo dmesg -C

Double-check that the buffer is clear:

sudo dmesg | grep USB

You should get no output with this command.

Do not connect the power cable to the switch yet! Connect the console cable only. Now, re-run the dmesg command you just ran; there should now be output from the buffer. Look at the very end of the final line: you should see something like

ttyUSB0

Make a note of this.

Now we'll enter Minicom setup mode and make sure the connection is correctly configured to display Cisco console information.

sudo minicom -s

Use your arrow keys to select 'serial port setup' and hit Enter. We're checking two options: that the serial device is set to our USB port, and that the baud rate is the correct speed. 'Serial Device' is at the top of the list; hit 'a' to go to it, and replace whatever is after the '/dev/' with ttyUSB0 (or whatever line you found in the earlier output). Hit enter. 'Serial Device' should now be something like:

/dev/ttyUSB0

Next, look at line E, for the bit rate: it should say 9600. If it doesn't, hit 'e', hit 'c' to select 9600 in the window that appears, and hit Enter. Now hit Enter again, select 'Save setup as dfl' ('dfl' meaning 'default'), and hit Enter once more. Select 'Exit,' and now you should see the console come up.

Connect the power to the switch or router. The device will boot, and then you should be able to enter the console.