[lwip-devel] [patch #8312] Congestion problem

[Marek NOVAK]

URL:
  <http://savannah.nongnu.org/patch/?8312>

                 Summary: Congestion problem
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: ok2nmz
            Submitted on: Wed 12 Feb 2014 12:25:32 PM GMT
                Category: TCP
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None

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Details:

Hello everybody,
 First, I'd like to say thank you to every single developper who has worked on
LwIP. It is such a nice piece of code!

Now for what I found out.
I am using LPC1768 as my platform and I wrote a simple telnet implementation
using RAW api. My system is quite short on memory (2x32kB) and as I fear
memory fragmentation, I am using pools for all dynamically
allocated/deallocated memory.
If I try to send a lot of querries to my telnet, the TCP connections hangs
with output queue full and keeps retransmitting everything and for me, it
seems like LwIP starts ignoring any ACK sent to these retransmissions. Some
time afterwards, LwIP resets the TCP connection, since the max number of
retransmissions is reached.
However, when I changed this from:
#define TCP_OVERSIZE    0
#define LWIP_NETIF_TX_SINGLE_PBUF  0

to 

#define TCP_OVERSIZE    TCP_MSS
#define LWIP_NETIF_TX_SINGLE_PBUF   1 

The problems disappeared.

I am using LwIP head version.

I hope it helps somebody... 

Regards from the Czech republic, BUT FEEC university in Brno,
 Marek Novak




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