Re: [lwip-users] Question about socket send

[Kieran Mansley]

On Mon, 2009-07-20 at 20:22 -0700, megatron wrote:
> I think it's may not be the fault of WINXP,nor lwip,though lwip has the
> problem that you describled above.It's probably  the bug  of the TCP test
> softerware that I use,it doesn't  read the data that TCP has received,so the
> window gets smaller and smaller.Is that possible?

Yes.  If the receiving application is not reading the data, then the
observed behaviour is correct and we don't need to worry.

> The packet captured when
> slow shows ,there are many duplicated ack and fast retransmission.How does
> this happen? Due to occasionally run out of memery?The lwip stats shows
> there are still occasionally run out of  memery.

Duplicate acks and fast retransmissions means you're either loosing or
corrupting data.  There are lots of possible reasons for this: it could
be running out of memory as you describe, or your lwIP device could
simply be too slow to keep up with the arriving packet rate and so they
get dropped by your driver.

Kieran