[lwip-devel] [bug #35015] Lost segments over wireless access point

[Brad Benjamin]

URL:
  <http://savannah.nongnu.org/bugs/?35015>

                 Summary: Lost segments over wireless access point
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: bradbenj5952
            Submitted on: Thu 08 Dec 2011 04:58:06 PM GMT
                Category: TCP
                Severity: 3 - Normal
              Item Group: Faulty Behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: 
            lwIP version: 1.4.0

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Details:

I'm using an OS port, sequential API (netconn), MSS == 536, window is 2 * MSS.
Our application has a web server and serves up content from a microSD card.
All works very well when browsing over a wired network. However, whenever
browsing is attempted using a client which connects via WiFi, lwIP frequently
appears to lose segments from which it fails to recover. The net effect of
this behavior is that netconn_write() fails to return to the server thread
because the op_completed semaphore is never signaled by the TCP core. I've
attached a PCAP file which shows a typical session. This scenario is very
repeatable. You'll notice in the PCAP trace that there is a lost segment near
the session start from which lwIP recovers gracefully, however, later in the
session there is another lost segment from which it does not recover.

CPU: STM32F107VC
ETH Driver: stm32_eth V1.1
PHY: DP83848



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File Attachments:


-------------------------------------------------------
Date: Thu 08 Dec 2011 04:58:06 PM GMT  Name: Lost Segments.pcap  Size: 39kB  
By: bradbenj5952
Typical lost segment sessions
<http://savannah.nongnu.org/bugs/download.php?file_id=24547>

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