I've always felt that my networking skills were somewhat lacking. I passed all of the Cisco courses in school, but at the time, I think I was just too bogged down with other coursework that I never really had a chance to go back and learn it really well, and in-depth. Now, I'm kicking myself a little bit that I didn't listen better, but I think I'll force myself to learn it better now if I'm going at my own pace and I want to learn it for me, rather than a professor forcing me to do so.
As such, I went out and bought an older Cisco Switch on eBay (Catalyst 3550). Rather than connecting to it via telnet/SSH (which I'll do eventually), the initial configuration has to be done over a console (rollover) cable. I had a little bit of trouble getting my Mac to see the device initially, so I'm writing up the steps on how to do that here. Mostly for myself, because I know I'll forget, but for others as well.
The first thing you'll need is to get a rollover cable. It looks like this:
Sorry for the poor image quality, but you get the idea. One one end is an RJ-45 (Ethernet) connector, and on the other is a serial connector. The problem, however, is that most Macs (or any computer for that matter) these days, don't have a serial port. Rather than keeping an old computer around (which I know a few people do just to have access to that port), you can buy an adapter.
Once the rollover cable and adapter are connected together, go ahead and insert the RJ-45 end of the connector into the "Console" port on your Cisco Device. Insert the USB end into your Mac. The console port on your device should look something like this and will be labeled "CON" or "CONSOLE":
Next, you'll have to download the driver for your serial device. You can do this by visiting http://plugable.com/drivers/prolific/ and downloading the Prolific Drivers. As of this writing, you'll want the one entitled, "PL2303 Prolific Mac OS X 10.9, 10.10, and 10.11 v1.6.0". Install the software and then reboot.
Next, open up Terminal and type:
ioreg -c IOSerialBSDClient | grep usb
You should see something along the lines of:
Next, open "System Preferences" and then "Network". Verify that you have something along the lines of "USB Serial Controller D":
Last, go back to your terminal and type
If everything was done correctly, you should now be talking to your switch/router/device!