2511 Terminal Server - buffered characters or noise?

[Edwin Summers]

I have a 2511 serving as a terminal server for some routers and switches in a lab.  Async ports on the 2511 are connected to the device console ports, and reverse telnet used to access the consoles from elsewhere on the network.

Once in a while when I connect to a device, several (a few pages) lines out output flow across the screen.  The "output" appears to actually be feeding in to the connected device's command line, as on a few occasions the "output" has caused a password change or other changes on the target device (the controlled device, not the 2511).  I am not sure if this is somehow buffered output from another session that is being dumped, some sort of buffer on the target device that is being re-issued upon connection, or perhaps something from my terminal program (I frequently use PuTTY; Haven't tried this with any other program yet) that is being triggered by some special character when the terminal server connects.

It's not quite garbage - all of the output I can see are commands or other display from a Cisco session.  I'm just not sure where it's coming from, why, or what is triggering it.  Many times I do not "exit" out of a console session on the lab devices (opting instead to break, sometimes I disconnect the session but most often I probably just leave it hanging).  I typically must clear the line twice before I access a device.  Perhaps this may be part of the issue..?

Thanks in advance for any thoughts,

Ed

[Richard Burts · Accepted solution]

Ed

Can you tell us whether your async line configuration includes the command no exec?

I have seen situations where async lines used for reverse telnet/terminal server and configured with the default setting of exec will send extra/garbage characters to the console of the controlled device.

HTH

Rick

[Edwin Summers]

Richard, thanks for the note.  I just added the command and will test it out through today.  If all appears well by end of the day will mark as corrected.  Appreciate the advice!

[johnbehring]

This worked for me, thanks for this helpful solution Rick! : )

I added, no exec to my line 33 64 and now I can login to my routers and firewall

with out a bunch of garbage text.

For Ed: (I know the post is 4 years old, sorry! This may be helpful to some beginners though.)

Below are the commands I used to get this to work, may be different depending on your line configuration.

Router>enable

Router#conf t

Router(config)#line 33 64

Router(config-line)#no exec

Router(config-line)#exit

Router(config)#exit

Router#show run

The above command is to check to see is the no exec command was added to your config.

And lastly don't forget to save once everything looks good....

Router#wr

John B