Serial Driver for PPP - that runs in Half Duplex Mode

Serial Driver for PPP - that runs in Half Duplex Mode

[Vanitha Ramaswami]

Hi All,
Is there a serial PPP Driver , that is capable of operating in half duplex 
mode. I have a radio that operates in half duplex mode and it has a serial 
interface. I want to establish a Point to Point connection between two 
Radios.

Do you have a serial port PPP Driver that supports half-duplex mode of 
operation ?. i.e.  I need RTS to be active when you are transmitting data 
and to be inactive to receive.

Thanks
Vanitha

Re: Serial Driver for PPP - that runs in Half Duplex Mode

[Alan Cox]

On Maw, 2004-08-17 at 11:56, Vanitha Ramaswami wrote:
> Do you have a serial port PPP Driver that supports half-duplex mode of 
> operation ?. i.e.  I need RTS to be active when you are transmitting data 
> and to be inactive to receive.

You can do this with a user space helper if performance isnt critical
(ie its not megabits). Create a tty/pty pair. Plug pppd one side of it
and run your own program the other side between it and the real tty.

This is how the old scarabd radio driver worked, although not using PPP
because we found that with the losses we got on radio other protocols
worked better.

RE: Serial Driver for PPP - that runs in Half Duplex Mode

[Vanitha Ramaswami]

Hello,
    Thanks for your mail. Can you let me know what are the other protocols that performs better than PPP ?

Thanks
Vanitha

-----Original Message-----
From:	Alan Cox [SMTP:alan@lxorguk.ukuu.org.uk]
Sent:	Tuesday, August 17, 2004 10:12 PM
To:	vanitha@agilis.st.com.sg
Cc:	'linux-kernel@vger.kernel.org'
Subject:	Re: Serial Driver for PPP - that runs in Half Duplex Mode

On Maw, 2004-08-17 at 11:56, Vanitha Ramaswami wrote:
> Do you have a serial port PPP Driver that supports half-duplex mode of 
> operation ?. i.e.  I need RTS to be active when you are transmitting data 
> and to be inactive to receive.

You can do this with a user space helper if performance isnt critical
(ie its not megabits). Create a tty/pty pair. Plug pppd one side of it
and run your own program the other side between it and the real tty.

This is how the old scarabd radio driver worked, although not using PPP
because we found that with the losses we got on radio other protocols
worked better.

RE: Serial Driver for PPP - that runs in Half Duplex Mode

[Alan Cox]

On Mer, 2004-08-18 at 12:36, Vanitha Ramaswami wrote:
> Hello,
>     Thanks for your mail. Can you let me know what are the other protocols that performs better than PPP ?

That will depend upon your link quality. If you drop a lot of frames
then a link layer reliable protocol or FEC based protocol will do
better. We used AX.25 (LAP-B with addressing). On radios that do their
own reliability/error handling IP is often just fine (as with 802.11)