RE: MTU greater than rcv.wnd
> Small MTU will reduce performance somewhat because of overhead.In this particular case, receive window is less than 1*MTU, smaller negotiated
MSS may actually help. With big MSS, if a segment is lost, the only way to
recover that is a timeout. But if MSS is smaller, multiple segments can be
sent. This means that fast retransmit can happen. Since RTO is usually
bigger than RTT (in BSD's case, it can be much bigger), this definitely helps
in recovery. But the MSS has to be small enough to allow at least 4 segments
to be sent in a window.