TCP_QUEUE_OOSEQ is set at default, enabled. In order to keep the amount of generated debug output to a minimum since this extra processing (delay) somehow reduces the occurrence of these issues, I have only TCP_INPUT_DEBUG and MEMP_DEBUG enabled, and also commented the following lines:
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("+-+-+-+-+-+-+-+-+-+-+-+-+-+- tcp_input: flags
"));
tcp_debug_print_flags(TCPH_FLAGS(tcphdr));
LWIP_DEBUGF(TCP_INPUT_DEBUG, ("-+-+-+-+-+-+-+-+-+-+-+-+-+-+\n"));
Otherwise, no code changes were performed. The debug output:
SYN-SENT: ackno 6558 pcb->snd_nxt 6558 unacked 6557
tcp_receive: ACK for 6662, unacked->seqno 6558:6662
tcp_receive: removing 6558:6662 from pcb->unacked
tcp_input: packet discarded due to failing checksum 0xe4db
tcp_receive: duplicate seqno 2971771236
tcp_input: packet discarded due to failing checksum 0x3b18
tcp_receive: duplicate seqno 2971772867
tcp_input: packet discarded due to failing checksum 0x0e15
The capture is attached. 192.168.0.169 is lwIP. In the previous emails I had
TCP_WND = 2*MSS, where MSS=1460, but for this capture I thought I could
simplify and have changed TCP_WND=MSS.
I'm not sure if there's enough information here to come to any conclusions.
The problem in my case is too much debug output partially fixes these issues,
even if I insert delays instead of the UART output function. Again this is
v1.3.0, no RTOS. Thanks for your help.
--- On Thu, 8/20/09, Kieran Mansley <[email protected]> wrote:
From: Kieran Mansley <[email protected]>
Subject: Re: [lwip-users] Delayed ACK behavior
To: "Mailing list for lwIP users" <[email protected]>
Date: Thursday, August 20, 2009, 3:48 AM
On Wed, 2009-08-19 at 09:27 -0700, JM wrote:
> I've attached the capture here again in case you don't have the older
> messages where it was originally sent. I did forget some pertinent
> info that might be helpful: it's v1.3.0, no RTOS, all processing is
> done in the ethernet interrupt. In the capture: .112 is the
> "transmitter" (my computer, .169 is the lwIP (Stellaris micro)
> board.
>
> Although I should have the debug output to include, in summary it
> complained of duplicate seqno when a packet was retransmitted
> from .112.
The debug output would be useful to see which of the retransmissions it
is complaining about.
Also, do you have TCP_QUEUE_OOSEQ on or off?
Kieran
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