[c-nsp] does duplex mismatch affect UDP throughput?

[Mikael Abrahamsson]

On Sun, 24 Jul 2011, Martin T wrote:

> So I guess duplex mismatch does affect UDP traffic as well? And why are 
> upload/download so unequal?

Because a duplex mismatch affects differently depending on direction.

The party which is in half duplex will see traffic coming the other 
direction as a late collission and will retransmit the packet from the 
switch/router buffer. The party in full duplex will never retransmit, so 
that packet is lost.

It's also a timing thing, a duplex mismatch is only a problem if there are 
packets being sent simultaneously in both directions. If you manage to 
time the traffic exactly so this never happens, then you won't see any 
packet loss at all.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se