Exosite internet client high count TCP/UDP receive packet drops at various times.

* Interesting how LWIP host can receive UDP packets without LWIP_UDP enabled in (lwipopts.h), so required by LWIP doc notes for DNS. Receive packet drops seemingly bomb the UDP (pcb) and at times quickly corrupt the memory pool Heap. LWIP IP debug shows DNS packets are received and transmitted on UDP port 53.

LWIP web Wiki states the definitions for (lwipopt.h) #defines are listed in (opt.h),  Clearly is not the case as some defines cause compiler errors if or when a value is set as the text states. One example is the time outs define. You can't make this stuff up, it was here all along. Seemingly many Ethernet configuration parameters are being enabled from (opt.h) when (#ifndef) in (lwipopt.h) making it impossible to trouble shoot heap memory issues. 

http://lwip.wikia.com/wiki/LwIP_Wiki

Update high count packet drops:

2.24.2015: https://e2e.ti.com/support/microcontrollers/tiva_arm/f/908/t/417592

The Sys_Timeout list of argument value total is not asserted here if {NO_SYS == 1} in (lwipopts.h) 

/**
 * MEMP_NUM_SYS_TIMEOUT: the number of simultaneously active timeouts.
 * (requires NO_SYS==0)
 * The default number of timeouts is calculated here for all enabled modules.
 * The formula expects (argument list values) to be either '0' or '1'.
 */
#ifndef MEMP_NUM_SYS_TIMEOUT
#define MEMP_NUM_SYS_TIMEOUT     (LWIP_TCP + IP_REASSEMBLY + LWIP_ARP + (2*LWIP_DHCP) + LWIP_AUTOIP + LWIP_IGMP + LWIP_DNS + PPP_SUPPORT)
#endif

The reported time window mysteriously changed after posting to an all hour event.

Seemingly it is Not necessary to set DNS server LWIP options unless a DNS server will be running locally in the TCP stack. Exosite connect to server function has the host server IP address embedded in software and the (m2.exoiste.com) domain name is only placed in the http header per RFC packet transfer rules. The open socket function does not need to name resolve and likely only uses an outside DNS query to check for an internet connection to mark the socket ok.

No need for DNS timer in order to use (dns.c) symbols only for host name resolve function (dns_gethostbyname). Then (LWIP_DNS == 1) enable does not require LWIP_UDP== 1 to be enabled.

4.23.2015 Sneaky LWIP v.1.4.11 have most all NETIF setting configured in (opt.h). TI programmer only added a few overrides in (lwipopts.h). Many over rides do not function in (lwipopts.h) we must add {#include "lwip/opt.h"} then things get better in LWIP stack.

Notes:

Client DNS (per RFC) 1st broadcast query connectionless UDP53, if fails then connects to TCP 53 to get Host name to IP resolve.

Possible UDP memory leak LWIP issue and how UDP protocol even work when disabled in (lwipopts.h) makes for an interesting coffee break discussions at the water cooler.  LWIP services these two timers no matter if enable or disable here has no effect the timers still assert as shown below during host client timer asserting.

void
lwIPHostTimerHandler(void)
{
    uint32_t ui32IPAddr;
    err_t eError;

#if NO_SYS
    //if(HWREGBITW(&g_sEnet.ui32Flags, FLAG_TIMER_DNS_EN))
    //{
     //   dns_tmr();
    //}

    //if(HWREGBITW(&g_sEnet.ui32Flags, FLAG_TIMER_TCP_EN))
    //{
       // tcp_tmr();
   //}
#endif // #if NO_SYS

LWIP internal timer services both DNS/TCP timers. The two calls above post seem to be redundant. Auto IP DHCP should assign two Name servers IP addresses for (dns.c) name resolves.

//*****************************************************************************
//
// This function services all of the lwIP periodic timers, including TCP and
// Host timers.  This should be called from the lwIP context, which may be
// the Ethernet interrupt (in the case of a non-RTOS system) or the lwIP
// thread, in the event that an RTOS is used.
//
//*****************************************************************************
#if NO_SYS
static void
lwIPServiceTimers(void)
{
~~~~~~~~~~~~~~

    //
    // Service the DNS Timer
    //
#if LWIP_DNS
    if((g_ui32LocalTimer - g_ui32DNSTimer) >= DNS_TMR_INTERVAL)
    {
        g_ui32DNSTimer = g_ui32LocalTimer;
        dns_tmr();
    }
#endif

    //
    // Service the link timer.
    //
#if LWIP_AUTOIP || LWIP_DHCP
    if((g_ui32LocalTimer - g_ui32LinkTimer) >= LINK_TMR_INTERVAL)
    {
        g_ui32LinkTimer = g_ui32LocalTimer;
        lwIPLinkDetect();
    }
#endif
}
#endif