Re: [lwip-users] Recent tcp_rexmit() changes

[K.J. Mansley]

On Fri, 2004-07-23 at 13:38, K.J. Mansley wrote:

> Perhaps we should just implement Selective ACKs - that would certainly
> help in this case! 

Indeed, from the summary of the problem SACK is trying to solve:

"Multiple packet losses from a window of data can have a catastrophic
effect on TCP throughput. TCP uses a cumulative acknowledgment scheme in
which received segments that are not at the left edge of the receive
window are not acknowledged. This forces the sender to either wait a
roundtrip time to find out about each lost packet, or to unnecessarily
retransmit segments which have been correctly received."

(http://www.opalsoft.net/qos/TCP-90.htm)

Which seems to describe pretty much what you're seeing.

Would SACK be useful for you?  i.e. Do the clients you're communicating
with support it?

Kieran