NDK for TM4C129 ARP re-sending timing setting

Hi Kaz,

Thanks for providing all of that information.

I’ve analyzed the Wireshark capture. I don’t think increasing the ARP times will help you. I think the problem is that the NDK is not updating its ARP table when it receives the gratuitous ARP from the PC (PC announcing its new IP address).

By default, the NDK is configured to drop/ignore all gratuitous ARP packets. The following configuration parameter governs this behavior:

CFGITEM_IP_RTGARP /* How to handle received gratuitous ARP */

                                       /* 0 : discard them. (Default) */

                                       /* 1 : update MAC address of HOST, if it */

                                       /*     is already in the routing table. */

                                       /* 2 : add HOST to routing table, if it */

                                       /*     does NOT exist. If exists, update */

                                       /*     MAC address. */

Can you try adding the following configuration code to change the behavior for gratuitous ARPs? Note that you need to do this in C code at runtime, and a good place to do that is one of the NDK hook functions. The following steps should help you:

1. Update the application configuration file (*.cfg file) with the following code to add an NDK hook function:

var Global = xdc.useModule('ti.ndk.config.Global');

Global.stackInitHook = '&myInitFxn';

2. Add the following C code, that implements the myInitFxn() to configure the gratuitous ARP setting:

#include <netmain.h>

#include <stkmain.h>

void myInitFxn(HANDLE hCfg)

{

   int garpValue = 1;

   CfgAddEntry(hCfg, CFGTAG_IP, CFGITEM_IP_RTGARP, CFG_ADDMODE_UNIQUE,

           sizeof(uint), (UINT8 *)&garpValue, 0);

}

Steve