nobeastsofierce
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Joined: Thu May 22, 2014 1:36 am

USB-Serial Adapter missing characters from Cisco Router

Thu May 22, 2014 1:55 am

(Very) Brief Backstory: I want to make a console server, I want to plug in multiple USB-9 pin Serial adapters to a USB hub, and then connect the serial ports to console ports on Cisco Router/Switches. I can use netcat to telnet to various ports on the pi, to access the various console ports (for my homelab, in case I screw up the config on a router or switch, and can't telnet to it normally)

Right now I just have one USB-Serial adapter plugged directly into the Raspberry Pi. (Well I have two, I have tried them both, same issue)

Right now, I am using Minicom to connect to the serial device.

If I do a show ip int brief command, the output I get is garbage http://i.imgur.com/9kL7QLs.jpg

For those not familiar with Cisco IOS, it should be a nicely formed table, something like this: http://salopek.eu/repository/blog/6-9.png

I am pretty sure I have Minicom configured correctly.

Supporting info:

Raspberry Pi: Model B
OS: Raspbian Wheezy
USB Serial Adapter: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port

The USB adapter works flawlessly under windows. so I don't think there is any fault with it. Is it possible to update the driver? How do I go about doing that?

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FTrevorGowen
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Re: USB-Serial Adapter missing characters from Cisco Router

Thu May 22, 2014 8:06 am

nobeastsofierce wrote: ...
Right now, I am using Minicom to connect to the serial device.
If I do a show ip int brief command, the output I get is garbage http://i.imgur.com/9kL7QLs.jpg
For those not familiar with Cisco IOS, it should be a nicely formed table, something like this: http://salopek.eu/repository/blog/6-9.png
I am pretty sure I have Minicom configured correctly.
...
It might just be a "minicom issue". I couldn't get that working properly with a number of USB-to-serial devices but found GtkTerm (installed "by default" on my Ubuntu netbook) to work O.K.** What happens if you reduce the baud rate (if that's possible)?
Trev.
** http://www.cpmspectrepi.webspace.virgin ... pters.html,
http://www.cpmspectrepi.webspace.virgin ... apter.html,
http://www.cpmspectrepi.webspace.virgin ... rtRep.html
Still running Raspbian Jessie or Stretch on some older Pi's (an A, B1, B2, B+, P2B, 3xP0, P0W, 2xP3A+, P3B+, P3B, B+, A+ and a B2) but Buster on the P4B's. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

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DeeJay
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Re: USB-Serial Adapter missing characters from Cisco Router

Thu May 22, 2014 9:07 am

A couple of thoughts - I recall encountering similar problems in just this scenario of accessing a cisco console.

One is that although many usb serial adapters are based on the PL2303 chip they are not all equal in build-quality.

The other is to consider flow control. Is the ios device spitting out characters faster than you can cope with them, expecting the connected device to impose either hardware or software flow control until it is ready again? Maybe your Windows application is doing this by default and minicom is not?
How To Ask Questions The Smart Way: http://www.catb.org/~esr/faqs/smart-questions.html
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nobeastsofierce
Posts: 2
Joined: Thu May 22, 2014 1:36 am

Re: USB-Serial Adapter missing characters from Cisco Router

Thu May 22, 2014 5:08 pm

Thanks for the responses. I think I have resolved it.

I thought that maybe the Pi wasn't giving adequate power on the USB port, so on a hunch I decided to plug the adapter into a powered USB hub.

It works perfectly when I plug this USB hub into the Pi: http://i.imgur.com/emXTmik.png

Not sure if my logic is flawed or not, but the problem has definitely disappeared ;)

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