Re: [lwip-users] Window memory leak from retransmitted packets

[Kieran Mansley]

On Mon, 2009-06-22 at 12:32 +0100, David Ward wrote:
> Hi
> I wonder if anyone can help with a lwip problem on a Xilinx ML506  
> Virtex 5 evaluation board with a microblaze processor and Xilinx Lwip  
> 2.0

Any idea what version of lwIP that corresponds to?  We're still on 1.3.0
as the most recent release.

> We are using the raw packet implemetation with a single TCPIP socket  
> link between a windows PC and the development board. I have based my  
> code on the Xilinx web server examples.
> 
> Our link connects and runs for a while, then fails.
> Investigating with wireshark shows that on occasion lwip fails to ack  
> a packet or two causing the PC to perform a fast re-transmission, lwip  
> transmits an ack and the link re covers, except that our window size  
> has reduced by the size of the re-transmitted packet. It is this  
> 'window buffer leak' that causes the link to fail eventually.
> 
> Is there anything I am missing, or that I need to do to clear out  
> duplicate packets?

You could try disabling TCP_QUEUE_OOSEQ and see if your problem goes
away.  If it does, that suggests packets aren't being from from the out-
of-order segment list.

Kieran