Re: [lwip-users] http client causes server to stop sending data

[Kieran Mansley]

On Sat, 2005-01-08 at 10:57 -0800, Chris Frost wrote:

> Using tcpdump on the other side of lwip's slip interface, the tcp connection
> looks like this: The lwip-based client connects to the server, they connect.
> They client sends a request, the server acks, and begins responding with
> the http headers and content. I'm not very experience with tcp, but now I'll
> try to mention what looks interesting in what follows in the connection.
> For the first second or so, the client only acks once for every two server
> packets. Then there is a 1-1 until ~packet 100 on a particular test (~11secs)
> when the client begins sending ACKs more sporadically, groups of them
> together. The client is also sending multiple copies of each ACK.

Frame 92 looks a bit suspect: it's from 192.168.2.1 which is an address
that hasn't featured before.  It causes a RST to be sent, which will
terminate the connection.  If you can work out where that comes from,
you'll probably solve your problem.

It also sends a number of duplicate acknowledgements (frames 95, 97, and
99 are duplicates of 93) despite all the data being in the correct order
and none is lost.  What's also odd is that the other end doesn't do a
fast retransmit as a result of these duplicate acknowledgements.

It finally grinds to a halt because 192.168.2.2 thinks its missing a
packet (115 is the one its complaining is missing), but the
68.62.194.163 machine refuses to retransmit it.

Doesn't solve your problem, but might provide some hints about where to
look!

Kieran