Alcatel OmniSwitch 6900 - USB Console Port Cable

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Hi there,

I need your help with an Alcatel Omniswitch 6900-x20. I need to connect to the switch with the console port, to make a factory Reset on it because I don´t get the password anymore. It seems I can only access the console through the USB Console Port on the Switch, then my question is, what kind of Cable I need to connect the Switch (USB Port) to my Notebook (DB9M) ? I tried using a concerter USB/RS232 to connect with a RS232 Cable (Cisco), but nothing appears with Putty.
Thanks for your Help

Content-Key: 1763272866


Printed on: August 17, 2022 at 00:08 o'clock

Member: aqui
aqui Jan 27, 2022 updated at 19:15:51 (UTC)
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Its a serial connection, so far its correct. See HERE on Page 2-5.
DCE means that you perhaps do NOT need a crossover serial cable (null modem) like Cisco does.
A lot of vendors use straight through 1:1 here with RS 232 Pins 2 and 3 (RX and TX) not crossed. ...
I bet this will do the trick !
Member: Olivier
Olivier Jan 28, 2022 at 07:26:30 (UTC)
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Thanks for your answer, I guess you are right at this point. I guess I get the right cable here but how can I convert to USB ? The switch got only USB Console port. I tried with an DB9/USB Adapter but nothing happened. Do I need a special converter or cable ?
Member: aqui
aqui Jan 28, 2022, updated at Jan 30, 2022 at 14:08:23 (UTC)
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You are right. Unfortunately the Alcatel documentation on Page 3-2 is very unclear here. face-sad
The documentation states its definitely a serial Port and ist working in DCE mode.
The port can have 2 different types of connectors depending on the the model. RJ-45 and USB Type A.
OK, RJ-45 is pretty simple and common cause it uses mostly RX TX data with center pinning according the Cisco scheme.
With USB its always tricky how vendors implement this.
There are vendors who use an internal USB serial converter chip on the switchhardware itself. So here its sufficient to just plug in a standard USB cable (and have the right driver for the chipset of course !)
But also a lot of them who use USB ports have NO serail chipset inside and just put the raw serial RS232 terminal data on the USB Ports.
This is of course NOT standard like and confuses endusers a lot, cause nobody expects serial RS232 data on USB ports. Serail Ports are in generall RJ-45 or DB-9 connectors.
This is a bit a nasty vendor strategy, cause that way they can sell totally overpriced "special" cables for terminal access. face-sad
To sum it up...
Alcatel is very confusing here. The management guide: ...
says on page 2-6 IT IS an embedded USB serail chipset from Silabs and requires their drivers of course:
So its possible that its only a question of drivers if its an embedded chipset.

If Alcatel states its a serial port it can be one of these non standard USB ports with serial data on it. In 99% of the cases it follows the USB cabeling. So ground is also used as ground. Data+ is often TX and data- is RX. 5V is not in use on terminal cables, cause not required. Serial RS232 data only needs 3 pins.
If you do not use the Alcatel cable you probably need to pull out your soldering iron.
Take a cheap USB type A cable cut off the connector and solder the data and ground pins to a DB-9 connector following the above pinout. Maybe you need to swap between data + and - in case RX and TX pins are swapped. That can easily be found out when booting the switch. Usually you see a lot of terminal messages which then shows you have the right pinout.
Maybe also a RS-232 breakout box or breakout connector helps. You'll find also a lot of information on the web regarding this. ...