Re: [lwip-users] Decreasing window size problem

[Kieran Mansley]

On Fri, 2007-06-08 at 09:18 +0200, Per-Henrik Lundblom wrote:
> Now to the problem, lwIP doesn't split up
> the data in the unsent queue to fit into A's window. Is this really a
> problem?

Shouldn't be.  It might slow things down for a while, as it prevents B
sending, but if A is struggling to process the data that's probably not
a bad thing.

> In my case, A's window update is lost by B so that B doesn't know that A
> now accepts data packets with a size equal or larger than the packet in
> B's unsent queue. If A's window whould have been 0 bytes, then
> implementation of TCP persist timer into lwIP whould have solved the
> problem by letting B probe A for a window update. Now when A's window
> update is lost, I'm in a deadlock situation.

Hmm, yes, I can see what you're getting at.  The only solution here is
to get B to do zero-window style probes to get a window update from A.
Normally it would only have to do this when it actually has a zero
window available to send into, but we need it to probe whenever it has
seen a window that prevents it sending.  Splitting the data might also
work, but would rather complicate matters, and probably add more code.  

Kieran