#ICMP CHECKSUM PC#

I will even think that without the LWIP_ICMP defined it should still work when responding to a echo request from the host.īut if you are trying to build a ping command into the MCU then I think the ping will be implemented in the application layer. The ICMP is part of the LwiP's IP stack for diagnostic. In No 134, the MCU is sending the echo (ping reply) as follows. The checksum in the ping request is as follows.

#ICMP CHECKSUM PC#

In No 131, the PC tries to ping the MCU with a echo (ping) request. Is this correct?Ĭan you try one of TivaWare ethernet example (I used enet_lwip) and use the PC to ping the board? I just tried that and below is what I see on the wireshark. I assume that your PC is trying to send a ping command to the custom board. changed from the original, all of these were commented Ip_output_if (p, ip_current_dest_addr(), IP_HDRINCL, ICMP_TTL, 0, IP_PROTO_ICMP, inp) // Line 223 in icmp.c As far as I can tell this is the only thing holding my ping response hostage. LWIP_ICMP is defined to 1 and all of the checksums in the checksum options are defined to 1.Īt this point I am stuck and would like some help getting this checksum issue fixed. I have traced through ip_output_if and can not find a single place that modifies the checksum handed in through the payload buffer. When i have tried to step through this section I can see the checksum go into ip_output_if with a value and come back out with a 0. So, I have looked at a few other LWIP sources and found that the issue is in the icmp.c (ipv4) source file in the icmp_input function. Because the checksum is a 0 the response in my command line is 'Request timed out'. I have been trying to implement ping via LWIP into my custom TM4C board with little success.Īfter doing tracing on wireshark I have found that the board receives the ping and does respond but leaves the checksum as a 0 (all of this done on Windows 10).

Icmp checksum