Re: [lwip-users] Decreasing window size problem

[Per-Henrik Lundblom]

* Kieran Mansley <address@hidden> [070608 10:01]:

> 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.

Good, that is my understanding too =)

> > 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.  

I will look into implementing the persistent timer and using the same
mechanism for sending probes without the remote peer having a zero
window.

/PH

--
Per-Henrik Lundblom           epost: address@hidden
telefon: 0733-20 71 26        hemsida: www.whatever.nu