Help can't access my 2950 CLI

thehourman · March 2010

*I powered on my 2950 switch and enter some basic commands and saved them. Today, when I turned on the 2950(to do some lab practices) and my netbook can't access the CLI thru the console port using TeraTerm, the teraterm opens just fine, but I can't type a thing. I can see the cursor and I am using the right COM number.
Does anyone know how to fix this?

Thanks
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CiskHo · March 2010

Have you confirmed that the baud rate matches up between the terminal program settings and the switch's console port? Normally it would be 9600 but I don't know if you have changed that.

Dilbert65 · March 2010

also check to make sure your flow control and pick none if that is a option or xon/off. That and baud rate are the normal main reasons you cant connect via console.

thehourman · March 2010

OK it seems to work now.
What I did I unplugged the switch, while the TeraTerm is on, and replugged it back.
Now, I can see something on the Teraterm and it seems to be working back to normal.

Do I have to turn on TeraTerm before I turn on the switch to access the CLI?

I am using the USB to Serial, if that helps.

CiskHo · March 2010

thehourman wrote: »

OK it seems to work now.
What I did I unplugged the switch, while the TeraTerm is on, and replugged it back.

Is your configuration still there? Curious if you had saved the config with "copy run start" or "write".

thehourman wrote: »

Do I have to turn on TeraTerm before I turn on the switch to access the CLI? I am using the USB to Serial, if that helps.

I've never used teraterm but any program that would require you to turn the switch off in order to access the CLI is seriously flawed. I doubt that was the issue. Maybe you had a loose adapter cable or you mistakenly changed the switches baud rate to a value other than what was set on the terminal program, then didn't save it. Power cycling the switch would have changed the setting back to the settings listed after the last "copy run start" or "write".

Dilbert65 · March 2010

You shouldn't but with a usb to serial converter I have seen some odd things compared to a real serial port. IE the port just wont connect like it is locked up. I have to fully reboot the computer with a power down to get the usb to free up. I got tired of the usb and dug out a old win98 laptop that I use for my serial connections when I am in the lab.

I finally got a 2509 term server so I can telent from my regular laptop and roam the house to find a quiet spot.

thehourman · March 2010

CiskHo wrote: »

Is your configuration still there? Curious if you had saved the config with "copy run start" or "write".

I've never used teraterm but any program that would require you to turn the switch off in order to access the CLI is seriously flawed. I doubt that was the issue. Maybe you had a loose adapter cable or you mistakenly changed the switches baud rate to a value other than what was set on the terminal program, then didn't save it. Power cycling the switch would have changed the setting back to the settings listed after the last "copy run start" or "write".

Yes, my config is still there I use the copy running-config startup-config last night.

I double checked the cable before I made this thread.

@Dilbert65
I have no choice I don't have an old PC or any PC that has serial connection.

CiskHo · March 2010

Well, as long as the baud rates match, the stop bits are set to none, and the com port is available then it should connect. Even if the switch was stuck in ROMMON you would still see something on the terminal screen. Had to be a mismatch of settings, a loose cable, or an adapter issue. I can't think of anything else that would cause no response.... unless the switch's power cable was disconnected

Glad its back up now though

PS - Sometimes you need to double check which COM port the USB adapter is really mapped to under Windows Device Manager (COM settings). It changes sometimes if the adapter is unplugged or maybe even after hibernating or going into suspend mode. Depends on if/when the PC was rebooted, etc.

thehourman · March 2010

the switch was on, weird.

Also, how do you disconnect from your switch console after you finish your setup?
Do you just close the terminal?

CiskHo · March 2010

thehourman wrote: »

Also, how do you disconnect from your switch console after you finish your setup?
Do you just close the terminal?

I type "exit" in the CLI (just in case "exec-timeout" has not been set) which logs you off. But all you really need to do is unplug your cable or close the terminal app. You don't need to do anything "special". If your device has a connection to and can be accessed from the WAN then you may want to configure "exec-timeout x x" so that the device automatically closes the VTY connection after being idle for a set period of time. This prevents unauthorized people from logging into a VTY line that has been left in enable mode, etc. (I think).

thehourman · March 2010

OK thanks

captobvious · March 2010

CiskHo wrote: »

This prevents unauthorized people from logging into a VTY line that has been left in enable mode, etc. (I think).

Who took your CCNA:S test for you?

JK

CiskHo · March 2010

captobvious wrote: »

Who took your CCNA:S test for you?

JK

!!! As soon as I started studying for the SWITCH exam the Security stuff was leaking out of my skull. I never work with security related stuff at work and it doesn't look like I will be anytime soon either. When I took the exam I thought for sure I had failed... I had only read the cert guide once in a span of 3 weeks and had zero exposure to anything security related before that. Somehow managed a 900+ score. Easy test I guess

FWIW, I'm usually fine with that stuff if I have a few minutes to think about it. However, I usually don't put that much effort into forum responses while I am at work. Hopefully, I didn't lead the OP in the wrong direction! Maybe I should have said console line instead of VTY... The console is still a security hole for me as I have a PC with VNC connected to my device 24/7 and accessible from the WAN. Break my dinky VNC password and the device is accessible to a hacker...which is why I was thinking about the exec-timeout command. I have a habit of not logging off the console connection myself.

thehourman · March 2010

exec-timeout is 5 minutes by default, right?
I set my 2 minutes.
What exactly is logging synchronous?
It does not explained very well in Odom's book ICND1.

CiskHo · March 2010

thehourman wrote: »

exec-timeout is 5 minutes by default, right?

I'm not sure. I didn't think it was enabled at all unless you specifically configured it to be.

thehourman wrote: »

What exactly is logging synchronous?
It does not explained very well in Odom's book ICND1.

It keeps your terminal screen from getting all messed up (confusing) while you are typing in commands. Ex: You start typing "logging syn" then all this stuff about interfaces going up/down appears and puts your "logging syn" off the screen and you have to remember where you left off before finishing the command with "chronous".

I suggest using that command on all console and vty lines. It helps keep things looking "clean" especially if you are running debugs or are monitoring something on the terminal (like interface flaps, routing updates, etc).

CCNA Portable Command Guide defines it as: Appends the command line to a new line - no interruption from info items.

thehourman · March 2010

Do I have to type some subcommand before I execute the command logging synchronous?
The reason I asked is when I typed logging synchronous ? it gave me 3-4 more options. I don't know what they do though.

CiskHo · March 2010

thehourman wrote: »

Do I have to type some subcommand before I execute the command logging synchronous?
The reason I asked is when I typed logging synchronous ? it gave me 3-4 more options. I don't know what they do though.

The <cr> that you see after typing "logging synchronous" means that is a valid command. Just hit enter (carriage return). Don't worry about the other commands for CCNA or even CCNP. They are not needed.

Help can't access my 2950 CLI

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