On Sat, Sep 11, 2004 at 10:25:53AM -0700, Andrew Burgess wrote:In pratice people dont really demand hard realtime and it will be OK, but
the maximum time taken to transmit a UDP packet is unbounded, it uses
exponential backoff IIRC.That sounds like TCP. I think UDP is send and forget, if you want guaranteed delivery or sequencing you need a higher protocol like TCP. Or are you thinking of ethernet level collision detect and retransmit? Does that go on forever (unbounded)?I dont think so, but IP (including UDP) does. There is a difference between raw ethernet packets and UDP. Ethernet has checksums to detect problems (maybe in;c forward correction), but AFAICR it doesnt retransmit on its own, I would imagine that that is why the commercial audio-over-ethernet systems work.
So at what level in the tcp/ip stack does a collision get detected? From what I understand, if there is a collision on a network segment each end will backoff for a randomly chosen time and then retransmit. Is this at the ethernet, IP, or TCP level?
-Eric Rz.
