2901- how does one pass an incoming telnet session over a serial port

[terry.Haebich]

Current setup

==========

I have two serial devices utilising RS232 Rxd/Txd (no control signals) connections over two serial ports on an old IBM terminal server to a specialised server on the IP network:

Remote display -----RS232----- IBM terminal server (serial port 1) +++

                                                                                                   | ++++++IP++++++ Server

Remote sensor -----RS232----- IBM terminal server (serial port 2) +++

The first connection passes messages from a server via the IBM terminal server to a remote display.

The second connection passes a telnet session from the remote device to a server on the network

TELNET -eQ -f 123.4.5.6 2008

.......message........

Q

New setup

========

Replaced the IBM terminal server with a Cisco 2901 ISR with two of its serial ports (8 and 9) configured the same as the existing IBM serial port

interface Async0/0/8

description

no ip address

ip nat inside

ip virtual-reassembly in

encapsulation slip

!

interface Async0/0/9

description

no ip address

ip nat inside

ip virtual-reassembly in

encapsulation slip

!

line 0/0/0 0/0/15

terminal-type ansi

no exec

transport input all

transport output all

The first connection passes messages from a server via the 2901 ISR to a remote display.

The telnet session from the remote device does not "arrive" on the server (note the Noise count on this port)

#sh line

   Tty Line Typ     Tx/Rx    A Modem  Roty AccO AccI  Uses  Noise Overruns  Int

  0/0/8   11 TTY   9600/9600  -    -      -    -    -    19      0    0/0      -

  0/0/9   12 TTY   9600/9600  -    -      -    -    -     0      8    0/0      -

Any assistance to fault find/resolve is greatly appreciated

[Richard Burts]

I am certainly not authoritative on this. But I wonder if the no exec configured on Async0/0/9 might be the issue. What happens if you enable exec on that line?

HTH

Rick

[terry.Haebich]

Hi Rick,

            I need to organise site access to follow this suggestion up.

Researching this option I have found the following:

On the configuration of the HWIC lines, use the no exec command. The reason is that if any message is sent from the attached devices to the HWIC card (such as logging message) while there is no session running on that port, the router with the HWIC card will start an EXEC session for that port, thereby disabling the option to reverse telnet to that port.

Thanks,

            Terry