[p2p-hackers] Optimal UDP Message size for data streaming...

[David Barrett]

> -----Original Message-----
> From: Daniel Stutzbach
> 
> The right solution is to use path-MTU discovery.  Initially set your
> datagram size to be your local MTU, and set the Don't-Fragment bit in
> all your packets.  If you get back ICMP Needs Fragmentation messages,
> then you gradually lower the datagram size until they fit.  You can
> also include an extra field in your protocol's initial handshake so
> each side learns the other's local MTU (since *typically* the lowest
> MTU is at one of the two edges).  TCP does all of this for you
> behind-the-scenes.

Has anyone on this list gotten MTU discovery over UDP to work in the real
world?  And if so, is there truly such variance that it's worth it?  If the
range is 1472-1500 bytes, it seems like a pointless exercise.  If it's
1472-65536 bytes, then it's more interesting.

Basically, given that you've got to make your application work well on
small-MTU paths, is it worth the effort to find and use big MTUs or just
more practical to find the lowest common denominator?

-david