[p2p-hackers] UDP file transfer protocol peer review

[David Barrett]

coderman wrote:
> i've found the best results when the wireless transport layer takes
> the following 802.11 specific peculiarities into account:
> - if you are getting interference with other network / clients /
> microwaves the retransmission in layer 2 (802.11MAC) will cause
> intermittent single hop delays in excess of 1 or 2 seconds.

Am I understanding you correctly that even though UDP is unreliable, 
801.11 still does retransmission under some circumstances, and when it 
does it introduces a 1-2 second delay?  Does this delay only affect the 
packet being retransmitted, or does it affect it and all subsequent 
packets in the UDP flow?  In all connections?

> - packet loss without congestion is the norm and not the exception;
> both intermittent latency and intermittent loss must be tolerated to a
> greater degree.
> 
> a fun environment to tune a stack in.

Yes, no kidding.  Have you tried using any congestion control technique 
that doesn't rely upon packet loss as an indicator?  I'm still reading 
through the "TCP-Friendly" congestion control profile for DCCP that Wes 
recommended a while back.  My understanding is it's "equation based" (as 
opposed to packet-loss triggered?) but I haven't read far enough to know 
what that means, though.

-david