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Modem connected through Aux port not configurable.

Posted on 2007-03-20
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Last Modified: 2010-04-17
Hello

I followed the advice in this Question:

http://www.experts-exchange.com/Hardware/Networking_Hardware/Routers/Q_22407018.html

and I have a US Robotics 56K* Faxmodem Model 5686E

my sh line is like this:

   Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   Int
     0 CTY              -    -      -    -    -      0       0     0/0       -
*  129 AUX 115200/115200- inout     -    -    -      1       0     0/0       -
*  130 VTY              -    -      -    -    -     54       0     0/0       -
   131 VTY              -    -      -    -    -      6       0     0/0       -
   132 VTY              -    -      -    -    -      0       0     0/0       -
   133 VTY              -    -      -    -    -      0       0     0/0       -
   134 VTY              -    -      -    -    -      0       0     0/0       -

when I configure line 129 and reverse telnet to 2129 it asks me for a password (cisco)
and then says:

Password:
Password OK

afterwards I issue several commands but none of them work. what do you think the problem is?
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Question by:eggster34
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Expert Comment

by:giltjr
ID: 18761338
What errors do you get?

Try setting the speeds to 9600.  It is not the fastest in the world, but typically this is what Cicso supports.

You can also try and follow:

http://www.cisco.com/en/US/tech/tk801/tk36/technologies_tech_note09186a0080094bbc.shtml
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Author Comment

by:eggster34
ID: 18768146
I follow the instructions, reverse telnet into 2129 , it asks for the password, I enter it.
IT says password OK and then nothing happens. I enter the commands but it does not reply me.

I type at but I don'T see it on the screen.

I'm not sure what is wrong.

The cables I'm using are:

CAB-500RJ=

Description: RJ-45 to RJ-45 Cable

 CAB-25AS-MMOD=

Male DB-25 Modem Connector
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Expert Comment

by:giltjr
ID: 18768294
Do you actually get a command prompt?

Which model router do you have?
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Author Comment

by:eggster34
ID: 18768833
what do you mean by a command prompt?
I am connected to the router (2800 series) via a console cable and it works ok.
when I start the reverse telnet session, all I get is the password prompt and when I enter it, it says password OK and then does nothing else.
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Expert Comment

by:giltjr
ID: 18768891
Once you get connected you the router should come back with the router's name and when enable mode it should be followed by a "#".

Do you have the modem properly setup based on the Modem-Router Configuration Guide?  Things like not fixing the DTE speed on the modem and/or not using hardware flow control can really flak things out.
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Author Comment

by:eggster34
ID: 18774519
I know all that. I am able to follow the guide you have sent.
but I cannot reverse telnet into the modem through the aux port.
I can configure the modem as specified for a console port connection: I connect the modem to the pc, issue the commands in hyperterminal, and then connect the modem to the console port as specified. I dial into the modem, I get a reply and then nothing happens on screen. none of the commands I enter work.
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by:giltjr
ID: 18774710
--> then connect the modem to the console port

If I understand the directions correctly the modem should be connected to the AUX port.
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Author Comment

by:eggster34
ID: 18775941
I meant the problem on my original post.

when I do it through the AUX port, I can reverse telnet into the modem but after it accepts my password it does not allow any commands to be sent to the modem through the aux port. I type at but nothing happens.
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Expert Comment

by:giltjr
ID: 18776925
I am a bit confused on what you are trying to do.  The reverse telnet session is for configuring the modem that is connected to the AUX port of the router so that you can dial into that router to configure it from somplace else.
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Author Comment

by:eggster34
ID: 18783105
ok. let's start over. There are 2 methods of connecting to a cisco router via dial in through an external modem.

One is through the AUX port, the other is through the console port. For both methods, you need to initially configure the modem before it's ready, and there are two methods to do that. 1- through the aux port of the router via reverse telnet. 2- through the serial port of a pc via hyperterminal.

My problem is that. I cannot reverse telnet into the modem from the AUX port but I can configure it through hyperterm. But even when I configure it through the hyperterm, neither the aux port method nor the console port method works. the modem auto-answers but the router is unreachable through the modem.
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Expert Comment

by:giltjr
ID: 18784132
It sounds like the DTE speed or the modem is not fixed at the same speed as the AUX port, the modem is not setup for hardware flow control, or both.  Can you see RTS/CTS flashing when you when you dial in?
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Author Comment

by:eggster34
ID: 18792487
how do I fix DTE speed?

I follow these guides to the letter:

for config through the aux port:
http://www.cisco.com/en/US/tech/tk801/tk36/technologies_tech_note09186a0080094bbc.shtml

for config through the console port:
http://www.cisco.com/en/US/tech/tk801/tk36/technologies_tech_note09186a00800941c9.shtml

Note: When I connect the modem to one of my desktops through the serial port of the desktop, it does NOT with the following cables as advertised by cisco:

PC -> db9 to rj45 adapter -> rj45 to rj45 rolled cable -> rj45 to db25 adapter -> modem

however I can use the same db9 to rj45 adapter -> rj45 to rj45 rolled cable to configure the router through the console port. I have tried several rj45 to db25 adapters (all branded cisco) with this usr modem and none of them worked. When I try a null modem cable provided by Belkin, I can easily connect the modem to the desktop, though. Could all of my rj45 to db25 adapters be problematic?

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Expert Comment

by:giltjr
ID: 18793029
You need to do this on the modem.  With the modem connected to your PC set your PC's DTE port speed to 9600, configure the modem with the following string:

     AT&B1&N6

You need to set any other modem configuration parameters and then write the config as the modems default config.

What do you mean by "rj45 rolled" cable?

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Author Comment

by:eggster34
ID: 18799034
giltir, do you not know what a rolled cable is?!?
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Expert Comment

by:giltjr
ID: 18801060
I have been doing networking for 25 years and have never heard the term "rolled cable."
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Author Comment

by:eggster34
ID: 18801643
mmmm
it's what cisco calls its console cables.
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Accepted Solution

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giltjr earned 500 total points
ID: 18802184
I just checked the Cicso site and saw that.  I was taught these were mirrored cables because the wires would appear as if you were holding on end up to a mirror.  I can see the term rolled because you are "rolling" the cable over.

Now that you have taught me something.  The rolled cable could be causing your problem in attempting to communicate with the modem.

It would be better if you could get a normal serial cable that is DB9 on one and and DB25 on the other end.   But if you can't get a serail cable, then try a straight through   cable.
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Author Comment

by:eggster34
ID: 18812529
I realized what the problem was.
the guides mention a rolled cable with the part number CAB-500RJ= , but that part number is NOT a rolled cable.
I'll accept your answer above since you pointed out the problem in a way.

Many thanks indeed. We all learned something from this.
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Expert Comment

by:giltjr
ID: 18812814
Great glad to see you got it working, thanks for the points and yes we both did learn from this.
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