On Apr 15, 2007, at 1:49 AM, Petri Helenius wrote:
Marshall Eubanks wrote:
I advise people doing streaming to not use MTU's larger than ~1450
for these sorts of reasons.
The unfortunate side-effect of that is that most prominent
streaming apps (don't know about Youtube though) then send
fragmented UDP packets which leads to reassembly overhead and in
case of lost packets, a significantly larger lost data than
neccessary.
Pete
Dear Pete;
The streaming servers that I have dealt with (such as Darwin
Streaming Server) do the fragmentation at the application layer. They
thus send out lots of packets at or near (in this case) 1450 bytes,
but they are not UDP fragments.
That's the whole point - many networks will not deliver fragments at
all, much less the increased risk of loss when they do. (I use Cox
Cable at home, and this network apparently does not forward fragments
and also has an apparent MTU of 1480 bytes.)
Just looked at a YouTube dump, btw, and almost all of the packets are
1448 bytes.
Regards
Marshall
Kind regards
Peter and Karin Dambier
Regards
Marshall
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