Catalyst 2960 24TT-L - No Console Output - Page 2

ChristianJoel · ‎10-07-2022

Hello!

I have two catalyst 2960 24TT-L switches, and I cannot get any output from them via the serial cable. I have tried using both PuTTY and TeraTerm, and made sure the serial cable is not defective. I have also tried switching BAUD rates, but that didn't work either. There is no output on boot or when I hold down the mode button.

The strange thing is when I connect those switches to another cisco switch and do a show cdp neighbor command, I can see both switches on there, which tells me that they are alive.

Any help is appreciated.

Thank you.

ChristianJoel · ‎10-17-2022

This is one of the switches with no console output.

Richard Burts · ‎10-18-2022

Thank you for clarifying that this config is from one of the switches with no console output. I am curious how you got this config if there is no console access and no ability to SSH or telnet to the switch?

It is interesting to note in the configuration that vlan 1 interface is configured to learn an IP via DHCP. So that might be a reason supporting my suggestion of configuring a DHCP scope on the switch that these problem switches connect to.

HTH

Rick

ChristianJoel · ‎10-20-2022

So interestingly, the way I was able to get this output is by using telnet. I can blind type commands by guessing what's on the screen while using console cable. So I configured vlan 1 to use DHCP and enabled secret for priv exec and vty lines. Isn't that fun?

Richard Burts · ‎10-20-2022

It is a very nice approach to use the console connection, type blind to make some config changes, and then use telnet to get the output. Well deserved +5 for a creative approach.

I would think the fact that the console accepted input would prove that the issue here is not baud rate.

Perhaps the output of show line might be helpful?

HTH

Rick

ChristianJoel · ‎10-23-2022

I would first like to apologize for the late response. I am trying to tshoot this issue for a school I work at and don't have access to the equipment on all days. With that said, I did get a show line and a show line console 0 output. One thing I noticed was that the stop bits on line 0 were set to 2 so I adjusted TeraTerm with the same config but no luck.

Hopefully you can see something that I don't.

Richard Burts · ‎10-23-2022

Thanks for the response and the additional information. The output does seem to confirm that the baud setting of the console is correct. I do not see anything in the output that looks like a problem.

The fact that you are able to type commands blind and they work does suggest that the input function of the console is working, but the output function is not.

Just to nail down one thing can you confirm that the computer you are using and the console cable you are using do work correctly on other Cisco devices?

Do you have the ability to open cases with Cisco TAC? If so they might be able to find something, or to arrange for RMA. If not then I don't know that there is anything else I can suggest.

HTH

Rick

ChristianJoel · ‎10-26-2022

Thank you for the response. I can confirm that the computer I am using is working correctly with other cisco equipment. I have also tried using a USB console cable but that didn't work either. I will have to check with my school admin about Cisco TAC.

Thank you for all the help you have provided so far. Appreciate it.

Richard Burts · ‎10-27-2022

You are welcome. Thank you for confirming that the computer and cable that you are using does work correctly on other Cisco gear. I can not think of any software or configuration issue that would produce these symptoms. I hope that you are successful in opening a case with Cisco TAC.

HTH

Rick

Joseph W. Doherty · ‎10-20-2022

BTW, years (decades) ago when I used "real" teletype video consoles, occasionally ran into the issue of whether the host computer system or the terminal should echo output. If neither host or terminal echoed output, nothing would appear as you typed. If both echoed typed input, everything typed would appear twice.

In this case, since you're seeing no output at all, don't believe it's as simple as an echo or not option (beyond perhaps seeing what you type, i.e. even with local echo).

Also BTW, wonder if your RS232 connection is working on the TX side, from terminal, but not working RX side from terminal. (A RS232 break-out box, I believe, could answer this question.)