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New Member

Reverse Telnet Problems

I am building a lab with a 2509 for reverse telnet to the other routers. Everything is working fine except for one router. I am not able to reverse telnet to that one router. When I connect directly to that router via console, I have no problems, but reverse telnet to the console port won't work. There is no config on the target router.

I have doublechecked ports, and I am using the correct ports. I have swapped cables and that didn't work. I was able to connect twice BRIEFLY, but it would hang after a couple of lines. I have also noticed that the light near the asynch port on my 2509 goes off and on unpredictably.

The most frustrating part is that I can't tell if the problem is the target router (which works fine and allows console connections no problem), The asynch cables (serial octal, not RJ rollovers), or the 2509 access router.

The only consistent thing I've noticed is that the line I am trying to access and having trouble with is marked with an (*) in the show line (below). I can't tell what that means.

Many thanks for any assistance.

Here is the output for my 2509-

(the router I'm having trouble with is on TTY 1)

router#sh line

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

0 CTY - - - - - 0 0 0/0

* 1 TTY 9600/9600 - - - - - 2 2 0/0

2 TTY 9600/9600 - - - - - 3 1 0/0

3 TTY 9600/9600 - - - - - 2 0 0/0

4 TTY 9600/9600 - - - - - 3 1 0/0

5 TTY 9600/9600 - - - - - 0 6 0/0

6 TTY 9600/9600 - - - - - 0 0 0/0

7 TTY 9600/9600 - - - - - 0 1 0/0

8 TTY 9600/9600 - - - - - 0 0 0/0

9 AUX 9600/9600 - - - - - 0 0 0/0

* 10 VTY - - - - - 2 0 0/0

11 VTY - - - - - 0 0 0/0

12 VTY - - - - - 0 0 0/0

13 VTY - - - - - 0 0 0/0

14 VTY - - - - - 0 0 0/0

Here is the output for the target router that I'm trying to console into via reverse telnet-

Router>sh line con 0

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

* 0 CTY - - - - - 0 0 0/0 -

Line 0, Location: "", Type: ""

Length: 24 lines, Width: 80 columns

Status: PSI Enabled, Ready, Active, Automore On

Capabilities: none

Capabilities: none

Group codes: 0

Special Chars: Escape Hold Stop Start Disconnect Activation

^^x none - - none

Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch

00:10:00 never none not set

Idle Session Disconnect Warning

never

Login-sequence User Response

00:00:30

Autoselect Initial Wait

not set

Modem type is unknown.

Session limit is not set.

Time since activation: 00:01:28

Editing is enabled.

History is enabled, history size is 10.

DNS resolution in show commands is enabled

Full user help is disabled

Allowed input transports are none.

Allowed output transports are lat pad v120 mop telnet rlogin nasi.

Preferred transport is lat.

No output characters are padded

No special data dispatching characters

5 REPLIES
New Member

Re: Reverse Telnet Problems

Hi,

the asterisk (*) near the line means that line is full, someone is connected to that line.If you see it after you tried to connect , it's ok. ( it shows your connection) but if you see asterisk before you try to connect , that's bad. It can be hung up. So try to clear that line before you connect, with command "clear line 1".

and try to change your cable with working one. We have same kinds of problems, and most of them are because of octal cables.

hope this helps..

New Member

Re: Reverse Telnet Problems

Thank you for your reply.

A sh line does show an asterisk even when this line is not in use. I entered clear line 1, and then it would let me connect- but I couldn't get a router> prompt. Just a "_".

I've also noticed that this line is showing noise when others aren't. I don't know what that means, but I think I'm on the right track.

router#sh line

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

* 1 TTY 9600/9600 - inout - - - 3 63 0/0

I don't think this is the octal cable because none of the other extensions will work with this router, but they work with other routers. This leads me to believe that there may be a problem with this router. Since this router has no config, and I can console fine to it when I'm near it, I can't see what the problem is. Could this be a physical layer issue?

Many thanks for any responses.

asr#sh line 1

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

* 1 TTY 9600/9600 - inout - - - 4 63 0/0

Line 1, Location: "", Type: "ANSI"

Length: 35 lines, Width: 90 columns

Baud rate (TX/RX) is 9600/9600, no parity, 2 stopbits, 8 databits

Status: Ready, Connected, Active

Capabilities: EXEC Suppressed, Hardware Flowcontrol In,

Hardware Flowcontrol Out, Modem Callout, Modem RI is CD

Modem state: Ready

Modem hardware state: noCTS DSR DTR RTS

Special Chars: Escape Hold Stop Start Disconnect Activation

^^x none - - none

Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch

never never none not set

Idle Session Disconnect Warning

never

Login-sequence User Response

00:00:30

Autoselect Initial Wait

not set

Modem type is unknown.

Session limit is not set.

Time since activation: 00:01:48

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 pad v120 telnet rlogin. Preferred is telnet.

No output characters are padded

No special data dispatching characters

New Member

Re: Reverse Telnet Problems

OK, here's where I'm at:

I found that I can get it to work (almost) by doing the following:

clear line

then connect to router via asynch

reboot router

At this point, the router will come up and do the initial boot process, and I can see that on screen, but it won't accept any input and will hang.

Does that make any sense to anyone?

New Member

Re: Reverse Telnet Problems

Do you have "no exec" command under the terminal server line configuration for that line? and can you send your configurations for terminal server line and the routers console line.

New Member

Re: Reverse Telnet Problems

Yes, I do have "no exec".

line con 0

line 1 8

no exec

exec-timeout 0 0

modem InOut

transport input all

flowcontrol hardware

The receiving router has no config.

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