Friday, January 30, 2009

Cisco 678 Console Cable, Ghetto Fabulous Style

I bought a Cisco 678 last night from a guy on craigslist for $10. After spending an hour and a half lost in Chanhassen (2 miles from hell), I found the place, only to discover that the guy didn't have the power brick or management cable. I thought, "no problem, I'll just stop by work on my way home and snag the PIX cable." Got to work and plugged the modem in real quick to make sure that it powered up correctly. Irony being the cruel bitch that she is, I got no output to the console. A little bit of hunting and I discovered that Cisco 6XX DSL modems do not use the same pinout as other Cisco devices. So I set to work making myself a console cable. After two frustrating hours of crimping, soldering, and cursing I had very little to show for my efforts, except knowing that plugging a straight-through ethernet cable into the Cisco DB9 to RJ45 terminal adapter would give me console output but no input.

What I difference a nights sleep makes. Got into the office this morning and figured I would play with the cable a little bit more. I read a little bit more about the terminal adapter and discovered that pin layout for the console cable is not 1>1, 2>2, etc., like I had originally assumed. Armed with this information, making a compatible cable was a snap. So here is how to make an "Ethernet" adapter cable that will interface the Cisco 6XX modem with a DB9 to RJ45 adapter.

Modem -> Terminal Adaptor/PC
6 -> 6
5 -> 3
4 -> 5
(Note: RJ45 pins are numbered 1-8 from right-to-left, looking at the front of the plug with the tab facing down)

Also, because I can never keep it straight, the DB9 plug on your PC is the male connector.

Here are a couple links that I found useful.
Making a Management Cable for 6XX
Console port pinouts for other Cisco devices

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