Subject: Re: [linux-audio-dev] Re: Audio synchronization, MIDI API
From: Eric Dantan Rzewnicki (eric_AT_zhevny.com)
Date: Mon Sep 13 2004 - 05:24:18 EEST
Steve Harris wrote:
> 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.
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