udp_mcast_ttl

#include <rtl.h>

BOOL udp_mcast_ttl (
    U8  socket,     /* UDP socket to set Time to Live. */
    U8* ttl);       /* TTL value - number of routers to cross. */

The udp_mcast_ttl function sets the Time to Live value for multicast packets of an UDP socket identified with a parameter socket. A TTL value controls the number of routers the packet can cross before being expired. For multicast message the default TTL value is 1. If this function is not called a default TTL value of 1 is assumed for all transmitted Multicast UDP datagrams.

The argument ttl specifies the TTL value for the UDP socket.

The udp_mcast_ttl function is in the RL-TCPnet library. The prototype is defined in rtl.h.

note

• This TTL value is not used for unicast UDP datagrams.

The udp_mcast_ttl function returns __TRUE when the TTL value successfully changed. Otherwise, the function returns __FALSE.

udp_get_socket, udp_open, udp_send

 ..
udp_soc = udp_get_socket (0, UDP_OPT_SEND_CS | UDP_OPT_CHK_CS, udp_callback);
if (udp_soc != 0) {
  /* Open UDP port 1000 for communication */
  udp_open (udp_soc, 1000);
  /* Let UDP Multicast datagrams cross a router. */
  udp_mcast_ttl (udp_soc, 2);
}