It turns out that most of the affected switches are running IOS 11.2 (8.5)
The line vty0 does not echo characters on Telnet sessions, but sessions
attached to line vty1 DOES echo.
Mysteriously, these switches have somehow been set to "exec-timeout 0 30"
on line vty 0 4 without any user intervention
sh line vty 0 produces:
Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise
Overruns
* 1 VTY - - - - - 23 0 0/0
Line 1, Location: "", Type: "ANSI"
Length: 24 lines, Width: 80 columns
Baud rate (TX/RX) is 9600/9600
Status: Ready, Active, No Exit Banner
Capabilities: none
Modem state: Ready
Special Chars: Escape Hold Stop Start Disconnect Activation
^^x none - - none
Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch
00:15:00 never none not
set
Idle Session Disconnect Warning
never
Modem type is unknown.
Session limit is not set.
Time since activation: never
Editing is enabled.
History is enabled, history size is 10.
DNS resolution in show commands is enabled
Full user help is disabled
Allowed transports are telnet. Preferred is telnet.
No output characters are padded
No special data dispatching characters
Sh line vty 1 produces:
Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise
Overruns
2 VTY - - - - - 2 0 0/0
Line 2, Location: "", Type: ""
Length: 24 lines, Width: 80 columns
Baud rate (TX/RX) is 9600/9600
Status: Ready, No Exit Banner
Capabilities: none
Modem state: Ready
Special Chars: Escape Hold Stop Start Disconnect Activation
^^x none - - none
Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch
00:15:00 never none not
set
Idle Session Disconnect Warning
never
Modem type is unknown.
Session limit is not set.
Time since activation: never
Editing is enabled.
History is enabled, history size is 10.
DNS resolution in show commands is enabled
Full user help is disabled
Allowed transports are telnet. Preferred is telnet.
No output characters are padded
No special data dispatching characters
The output for both lines appears identical to me.
So far, I've not found anything relevant on Cisco's Bug Database. This
seems rather strange behavior to me. All the afftected switches are in
production so I haven't had an opportunity to reboot them.
One thing I've noticed - while doing a "sh line vty0" and "sh line vty1"
minutes after the above output, the "Idle EXEC" value appears to be
variable. vty0 sometimes has an Idle EXEC value of 10:00, and vty1 has an
Idle EXEC value of 00:30. The value in the running config is "exec-timeout
0 30".
Apologies for the verbose post...
thanks,
-carl
George Robbins
<grr@shandakor.th To: CARL.P.HIRSCH@sargentlundy.com,
arsis.com> cisco-nsp@puck.nether.net
cc:
06/11/01 06:14 PM Subject: Re: [nsp] Telnet Character Echo
on Cat3524
try doing detailed "show line" for each of the vty's and see
if there's something different between a non-echo session and
a normal one.
there's a certain amount of state that seems to get saved between
inbound telnet sessions, that really sholdn't be, the most blatent
example being the "terminal length" value.
George
> From cisco-nsp-request@puck.nether.net Mon Jun 11 17:31:25 2001
> Resent-Date: Mon, 11 Jun 2001 17:31:20 -0400
> Received-Date: Mon, 11 Jun 2001 17:27:27 -0400
> To: cisco-nsp@puck.nether.net
> From: CARL.P.HIRSCH@sargentlundy.com
> Date: Mon, 11 Jun 2001 16:17:18 -0500
> X-MIMETrack: Serialize by Router on mail01/Sargentlundy(Release 5.0.7
|March 21, 2001) at
> 06/11/2001 04:17:24 PM
> Subject: [nsp] Telnet Character Echo on Cat3524
> Resent-From: cisco-nsp@puck.nether.net
> X-Mailing-List: <cisco-nsp@puck.nether.net> archive/latest/6769
> X-Loop: cisco-nsp@puck.nether.net
> Precedence: list
> Resent-Sender: cisco-nsp-request@puck.nether.net
>
> A number of our 3524 switches have stopped echoing characters during
Telnet
> sessions. For example - "sh run" would not be visible as you type it, but
> the command does go through.
>
> This can be reproduced from multiple terminals, so I'm assuming it's not
> Telnet client-related.
>
> Nothing in the config seems to be related to the issue.
>
> Any ideas?
>
> thanks,
> -carl hirsch
>
>
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