I'm developing an application on the Stellaris LM3S6965 platform with lwip 1.4.1, FreeRTOS 7.5.2 and Stellarisware 10636.
With a host Linux PC I'm sending a HTTP POST request (3011 byte payload) using wget connected to the target platform with a crossover cable.
I've attached a wireshark capture of the strange behavior. It appears that 3 packets are sent from the HTTP post request without an ACK being sent by the lwip system, then several seconds later the host PC resends the first packet, some duplicate ACKs occur, etc.
I wrote a more concise analysis of this before, but Nabble ate my message after I uploaded the capture file.. First and last time I'm using that.
I did some debugging in the Ethernet interface driver receive function and it appears that not all of the packets are arriving. Anyone have any ideas where to go from here? I'm not very familiar with Ethernet hardware drivers, so I don't know how they buffer data and what would cause them to lose a packet. Could I decrease my WND size to try and fix this?
Here are some of the TCP settings I have in my lwipopts.h file:
//#define LWIP_TCP 1
//#define TCP_TTL (IP_DEFAULT_TTL)
#define TCP_WND 4096 // default is 2048
//#define TCP_MAXRTX 12
//#define TCP_SYNMAXRTX 6
#define TCP_QUEUE_OOSEQ 1
#define TCP_MSS 1460 // default is 128
//#define TCP_CALCULATE_EFF_SEND_MSS 1
#define TCP_SND_BUF (2 * TCP_MSS)
//#define TCP_SND_QUEUELEN (4 * (TCP_SND_BUF/TCP_MSS))
//#define TCP_SNDLOWAT (TCP_SND_BUF/2)
//#define TCP_LISTEN_BACKLOG 0
//#define TCP_DEFAULT_LISTEN_BACKLOG 0xff
Thanks in advance for any assistance.
Element Green
http_post_delayed_ack.pcapng