10

In our office building, we have a Cisco SRW2048 switch. On the back, it has a serial port for console connections. I would like to connect this console port to my computer in my room.

The switch is located in the network room next to the ethernet patch panel which leads to all of the other rooms. I was wondering if it was possible to use that patch panel to connect to the switch's console port.

Would it work if I used 2 rollover cables? Like, if I connected one from the switch to the patch panel and another from the ethernet port in my room to the serial port on my computer?

If not, is there another way to connect to the switch without running a super-long serial cable along the floor from the network room to my room?

UPDATE: Yes, I know I should be using the web interface (or telnet) to access the switch. I just want to connect to the console port as a learning exercise or, you know, just for fun.

I'm just not sure what cable/adapters to use, since in the lab in school, the router/switches had RJ45 connectors as their console ports and we used rollover cables to connect to them. This switch has a RS232 (serial) connector as its console port and I wasn't sure how to interface with it through the ethernet patch panel.

UPDATE 2: Could I use a rollover cable on one end and a "null modem" adapter on the other?

  • 1
    Why do you want to connect to the console port? Couldn't you just get the switches IP address and connect that way? – Anthony Fornito Dec 12 '16 at 16:14
  • @AnthonyFornito: Yeah, I guess I could. I don't currently know what it is and nmap didn't seem to be of much help, but I could probably figure it out. I mostly wanted to connect to the console just for fun :-) – Rocket Hazmat Dec 12 '16 at 16:15
12

Use a straight through cable from the console port of the Cisco to the patch panel, and then a rollover from the port in the wall to your computer?

| improve this answer | |
12

You should be able to connect the console port to the patch panel with a rollover cable.

You must use a standard straight-through ethernet on the other end - NOT another rollover cable.

If it's viable, it would be much simpler to configure the switch with a management IP and SSH/telnet access.

| improve this answer | |
  • How would I connect the other end, though? Is there a straight-through "serial to ethernet" cable? – Rocket Hazmat Dec 12 '16 at 16:27
  • If a direct connection with your RS232-RJ45 cable works in the server room, why would you want to use a rollover (aka crossover) cable at all? – Jens Ehrich Dec 12 '16 at 16:28
  • Also, yes I know I should be connecting to the switch via it's web interface or telnet, but I want to see if I can connect to the console... just for fun! – Rocket Hazmat Dec 12 '16 at 16:28
  • @JensEhrich: Because I wasn't 100% sure what kind of cable I needed to use. In school, the router/switches we used had RJ45 connectors as their console ports and were connected to the PCs with rollover cables. This switch has a RS232 (serial) port as its console and I'm not sure how to connect it to my PC in the other room (since I don't have a laptop I can bring into the server room). – Rocket Hazmat Dec 12 '16 at 16:29
1

You need an odd number of rollovers, normally one or three, I recommend one. Specifically on my bench right now is a non rollover cisco/yoist adapter (about three inches long, rj-45 jack to female de-9 (also called db9), a rollover cisco/yoist adapter (differing from the previous only by pinout and label, and a cisco cable (3 ft long, blue, with rj45 plug on one end and and a female de-9 on the other). the cisco cable plugs from a dte (ie your computer) to a cisco router. To make the other adapters equivalent requires a rollover cable for the non rollover adapter (rollover cables connect pin one to pin eight), a straight through cable (standard ethernet, pin one to pin one) for the rollover adapter.

Now onto your question if we do it to the cisco standard you rollover the cable in the wall and the cables at both ends for a total of three rolls. I do not recommend this.

Simpler is to wire the building for ethernet, and use a standard ptach cable in the wiring closet, and put the only roll at the end where you convert to de-9, but you could put the roll in the closet and use a strait cable at the other end, the important part is that the total number of rolls be odd.

The other consideration is total length, which should be kept short as rs232 is not designed for long runs. If you need a long run you will need a repeater or media converter (I normally use rs422/485 or fibber optic or a terminal server) which need different cabling as most media converters are dce (null modems or gender changers and even number of rolls) and terminal servers use different pinnouts (your terminal server documentation will probably come with a pinnout for a cisco cable for use with your terminal server).

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.