[lwip-users] lwip does not ack retransmissions

[john bougs]

I have been having problems with lwip receiving retransmitted packets.

The attached wireshark capture is typical of the problem.

.107 is lwip, .102 is a telnet session on Windows where I have cut and pasted a 
file. 40K file.  A large portion of the file is transfered successfully before 
the capture.

@ packet 37 relative sequence 192 packet is transmitted with len = 128
@ packet 45 we start getting duplicate acks  = 192
@ packet 47 sequence 192 is resent ... this time only one byte
@ packet 52 we get ack = 193
@ packet 53 we start getting duplicate ack = 193
@ packet 56 seq 193 is transmitted len = 1
@ packet 62 ack=194
@ packet 63 we start getting duplicate ack = 194

up to this point things have been pretty consistent, after this point  
specifics may change slightly from run to run, but in all cases all we get are 
duplicate acks.

I am using lwip 1.3 on NXP LPC2368 with the following settings:

#define LWIP_DHCP 0
#define MEM_ALIGNMENT   4
#define NO_SYS          1
#define LWIP_SOCKET                     0
#define LWIP_NETCONN                    0
#define TCP_WND 512
#define PBUF_POOL_BUFSIZE (128+56)
#define PBUF_POOL_SIZE 8
#define IP_REASS_MAX_PBUFS              6


if I return PBUF_POOL_BUFSIZE, PBUF_POOL_SIZE and  IP_REASS_MAX_PBUFS to the 
defaults, things recover after a few seconds rather than going completly dead.

does anyone have any suggestion on what the problem may be?