On Fri, 2 Apr 1999, Stefano Giacometti wrote:
> I think I have the following choices about the implementation of a real-time
> brigde between two NIC:
>
> - I could try to work inside the NIC network driver (eg. tulip.c)
> to try to perform some actions on a packet-by-packet basis (maybe
> I have to work with very low bit rates...)
>
> - I could use RT-Linux to implement a RealTime module talking
> directly with my network adapter (but I remember there were
> some PIC adresses issues...)
>
> Do anyone of you has a clue about the feasibility of this idea?
>
> (PS, just to explain, the realtime work to be carried out is a sharp delayer
> on a packet basis...)
If you want to do this correctly, and have a controlled hardware system, you
should use 3c905B "Cyclone" cards. The Cyclone has the ability to schedule
packet *transmit* on a real-time basis. It delays the transmit attempt until
the on-chip timer matches the time value in the packet header.
Obviously Linux doesn't use this very specialized feature. To do it right
you need support in every switch along the connection for reserved bandwidth
and service priorities -- and all of the other issues that make doing ATM
correctly impossibly complex.
Donald Becker [EMAIL PROTECTED]
USRA-CESDIS, Center of Excellence in Space Data and Information Sciences.
Code 930.5, Goddard Space Flight Center, Greenbelt, MD. 20771
301-286-0882 http://cesdis.gsfc.nasa.gov/people/becker/whoiam.html
-
To unsubscribe from this list: send the line "unsubscribe linux-net" in
the body of a message to [EMAIL PROTECTED]
