diff --git a/CHANGELOG b/CHANGELOG
index 987bf244..c1b0a5f3 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -23,6 +23,13 @@ HISTORY
 
   ++ New features:
 
+  2007-03-11 Frédéric Bernon, Mace Gael, Steve Reynolds
+  * sockets.h, sockets.c, api.h, api_lib.c, api_msg.h, api_msg.c, igmp.h, igmp.c,
+    ip.c, netif.h, tcpip.c, opt.h:
+    New configuration option LWIP_IGMP to enable IGMP processing. Based on only one 
+    filter per all network interfaces. Declare a new function in netif to enable to
+    control the MAC filter (to reduce lwIP traffic processing).
+
   2007-03-11 Frédéric Bernon
   * tcp.h, tcp.c, sockets.c, tcp_out.c, tcp_in.c, opt.h: Keepalive values can
     be configured at run time with LWIP_TCP_KEEPALIVE, but don't change this
diff --git a/src/api/api_lib.c b/src/api/api_lib.c
index 6e5a7ab9..d784306d 100644
--- a/src/api/api_lib.c
+++ b/src/api/api_lib.c
@@ -682,6 +682,37 @@ netconn_close(struct netconn *conn)
   return conn->err;
 }
 
+#if LWIP_IGMP
+err_t
+netconn_join_leave_group (struct netconn *conn,
+                          struct ip_addr *multiaddr,
+                          struct ip_addr *interface,
+                          u16_t join_or_leave)
+{
+  struct api_msg msg;
+  struct ip_addr *ipaddr[2];
+
+  if (conn == NULL) {
+    return ERR_VAL;
+  }
+
+  if (conn->err != ERR_OK) {
+    return conn->err;
+  }
+
+  msg.type = API_MSG_JOIN_LEAVE;
+  msg.msg.conn = conn;
+  ipaddr[0] = multiaddr;
+  ipaddr[1] = interface;
+  msg.msg.msg.bc.ipaddr = (struct ip_addr *)ipaddr;
+  msg.msg.msg.bc.port = join_or_leave;
+  api_msg_post(&msg);
+  
+  sys_mbox_fetch(conn->mbox, NULL);
+  return conn->err;
+}
+#endif /* LWIP_IGMP */
+
 err_t
 netconn_err(struct netconn *conn)
 {
diff --git a/src/api/api_msg.c b/src/api/api_msg.c
index 325bc683..d62e1259 100644
--- a/src/api/api_msg.c
+++ b/src/api/api_msg.c
@@ -36,6 +36,7 @@
 #include "lwip/memp.h"
 #include "lwip/sys.h"
 #include "lwip/tcpip.h"
+#include "lwip/igmp.h"
 
 #if LWIP_RAW
 static u8_t
@@ -788,6 +789,41 @@ do_close(struct api_msg_msg *msg)
   }
   sys_mbox_post(msg->conn->mbox, NULL);
 }
+ 
+#if LWIP_IGMP
+static void
+do_join_leave_group(struct api_msg_msg *msg)
+{
+  err_t err = ERR_OK;
+  
+  if (msg->conn->pcb.tcp != NULL) {
+    switch (msg->conn->type) {
+#if LWIP_RAW
+    case NETCONN_RAW:
+      break;
+#endif
+#if LWIP_UDP
+    case NETCONN_UDPLITE:
+    case NETCONN_UDPNOCHKSUM:
+    case NETCONN_UDP:
+      switch(msg->msg.bc.port){
+        case NETCONN_JOIN:  err = igmp_joingroup (netif_default, ((struct ip_addr**)(msg->msg.bc.ipaddr))[0]); break;
+        case NETCONN_LEAVE: err = igmp_leavegroup(netif_default, ((struct ip_addr**)(msg->msg.bc.ipaddr))[0]); break;
+      }
+      break;
+#endif /* LWIP_UDP */
+#if LWIP_TCP
+    case NETCONN_TCP:
+        break;
+#endif
+    default:      
+      break;
+    }
+  }
+  msg->conn->err = err;      
+  sys_mbox_post(msg->conn->mbox, NULL);
+}
+#endif /* LWIP_IGMP */
 
 typedef void (* api_msg_decode)(struct api_msg_msg *msg);
 static api_msg_decode decode[API_MSG_MAX] = {
@@ -801,7 +837,10 @@ static api_msg_decode decode[API_MSG_MAX] = {
   do_send,
   do_recv,
   do_write,
-  do_close
+  do_close,
+#if LWIP_IGMP
+  do_join_leave_group
+#endif /* LWIP_IGMP */
   };
 void
 api_msg_input(struct api_msg *msg)
diff --git a/src/api/sockets.c b/src/api/sockets.c
index ce5ebfcb..5043b767 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -39,7 +39,7 @@
 #include "lwip/api.h"
 #include "lwip/arch.h"
 #include "lwip/sys.h"
-
+#include "lwip/igmp.h"
 #include "lwip/sockets.h"
 
 #define NUM_SOCKETS MEMP_NUM_NETCONN
@@ -1237,6 +1237,21 @@ int lwip_setsockopt (int s, int level, int optname, const void *optval, socklen_
         err = EINVAL;
       }
         break;
+    #if LWIP_IGMP
+    case IP_MULTICAST_TTL:
+     { if(( optlen != sizeof(char) ) && ( optlen != sizeof(int) )) //NOTE, some BSD implementation use "int", some others "char"
+        { err = EINVAL;
+        }
+       break;
+     }
+    case IP_ADD_MEMBERSHIP:
+    case IP_DROP_MEMBERSHIP:
+      { if( optlen < sizeof(struct ip_mreq) )
+         { err = EINVAL;
+         }
+        break;
+      }
+    #endif /* LWIP_IGMP */
       default:
       LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IP, UNIMPL: optname=0x%x, ..)\n", s, optname));
       err = ENOPROTOOPT;
@@ -1328,6 +1343,27 @@ int lwip_setsockopt (int s, int level, int optname, const void *optval, socklen_
       sock->conn->pcb.tcp->tos = (u8_t)(*(int*)optval);
       LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IP, IP_TOS, ..)-> %u\n", s, sock->conn->pcb.tcp->tos));
       break;
+    #if LWIP_IGMP
+    case IP_MULTICAST_TTL:
+     { if (optlen==sizeof(int))  sock->conn->pcb.tcp->ttl = (u8_t)(*(int*) optval);
+       if (optlen==sizeof(u8_t)) sock->conn->pcb.tcp->ttl = (u8_t)(*(u8_t*)optval);
+       break;
+     }
+    case IP_ADD_MEMBERSHIP:
+    case IP_DROP_MEMBERSHIP:
+     { /* If this is a TCP or a RAW socket, ignore these options. */
+       if ((sock->conn->type == NETCONN_TCP) || (sock->conn->type == NETCONN_RAW))
+        { err = EAFNOSUPPORT;
+        }
+       else
+        { struct ip_mreq *imr = (struct ip_mreq *)optval;
+          if (netconn_join_leave_group( sock->conn, (struct ip_addr *)&(imr->imr_multiaddr.s_addr), (struct ip_addr *)&(imr->imr_interface.s_addr), ((optname==IP_ADD_MEMBERSHIP)?NETCONN_JOIN:NETCONN_LEAVE)) < 0)
+           { err = EADDRNOTAVAIL;
+           }
+        }
+       break;
+     }
+    #endif /* LWIP_IGMP */
     }  /* switch */
     break;
 
diff --git a/src/api/tcpip.c b/src/api/tcpip.c
index cc55756c..0660d5be 100644
--- a/src/api/tcpip.c
+++ b/src/api/tcpip.c
@@ -45,6 +45,7 @@
 #include "lwip/tcp.h"
 
 #include "lwip/tcpip.h"
+#include "lwip/igmp.h"
 
 static void (* tcpip_init_done)(void *arg) = NULL;
 static void *tcpip_init_done_arg;
@@ -168,6 +169,9 @@ tcpip_thread(void *arg)
   sys_timeout(DHCP_COARSE_TIMER_SECS*1000, dhcp_timer_coarse, NULL);
   sys_timeout(DHCP_FINE_TIMER_MSECS, dhcp_timer_fine, NULL);
 #endif
+#if LWIP_IGMP
+  igmp_init();
+#endif
 
   if (tcpip_init_done != NULL) {
     tcpip_init_done(tcpip_init_done_arg);
diff --git a/src/core/ipv4/ip.c b/src/core/ipv4/ip.c
index 9d655f8b..5fa56fce 100644
--- a/src/core/ipv4/ip.c
+++ b/src/core/ipv4/ip.c
@@ -59,6 +59,9 @@
 #  include "lwip/dhcp.h"
 #endif /* LWIP_DHCP */
 
+#if LWIP_IGMP
+#  include "lwip/igmp.h"
+#endif /* LWIP_IGMP */
 
 /**
  * Initializes the IP layer.
@@ -227,28 +230,44 @@ ip_input(struct pbuf *p, struct netif *inp) {
   pbuf_realloc(p, ntohs(IPH_LEN(iphdr)));
 
   /* match packet against an interface, i.e. is this packet for us? */
-  for (netif = netif_list; netif != NULL; netif = netif->next) {
-
-    LWIP_DEBUGF(IP_DEBUG, ("ip_input: iphdr->dest 0x%"X32_F" netif->ip_addr 0x%"X32_F" (0x%"X32_F", 0x%"X32_F", 0x%"X32_F")\n",
-      iphdr->dest.addr, netif->ip_addr.addr,
-      iphdr->dest.addr & netif->netmask.addr,
-      netif->ip_addr.addr & netif->netmask.addr,
-      iphdr->dest.addr & ~(netif->netmask.addr)));
-
-    /* interface is up and configured? */
-    if ((netif_is_up(netif)) && (!ip_addr_isany(&(netif->ip_addr))))
-    {
-      /* unicast to this interface address? */
-      if (ip_addr_cmp(&(iphdr->dest), &(netif->ip_addr)) ||
-         /* or broadcast on this interface network address? */
-         ip_addr_isbroadcast(&(iphdr->dest), netif)) {
-        LWIP_DEBUGF(IP_DEBUG, ("ip_input: packet accepted on interface %c%c\n",
-          netif->name[0], netif->name[1]));
-        /* break out of for loop */
-        break;
+#if LWIP_IGMP
+  if (ip_addr_ismulticast(&(iphdr->dest)))
+   { if (lookfor_group( inp, &(iphdr->dest)))
+      { netif = inp;
       }
-    }
-  }
+     else
+      { netif = NULL;
+      } 
+   }
+  else
+   {
+#endif
+   for (netif = netif_list; netif != NULL; netif = netif->next) {
+
+     LWIP_DEBUGF(IP_DEBUG, ("ip_input: iphdr->dest 0x%"X32_F" netif->ip_addr 0x%"X32_F" (0x%"X32_F", 0x%"X32_F", 0x%"X32_F")\n",
+       iphdr->dest.addr, netif->ip_addr.addr,
+       iphdr->dest.addr & netif->netmask.addr,
+       netif->ip_addr.addr & netif->netmask.addr,
+       iphdr->dest.addr & ~(netif->netmask.addr)));
+
+     /* interface is up and configured? */
+     if ((netif_is_up(netif)) && (!ip_addr_isany(&(netif->ip_addr))))
+     {
+       /* unicast to this interface address? */
+       if (ip_addr_cmp(&(iphdr->dest), &(netif->ip_addr)) ||
+          /* or broadcast on this interface network address? */
+          ip_addr_isbroadcast(&(iphdr->dest), netif)) {
+         LWIP_DEBUGF(IP_DEBUG, ("ip_input: packet accepted on interface %c%c\n",
+           netif->name[0], netif->name[1]));
+         /* break out of for loop */
+         break;
+       }
+     }
+   }
+ #if LWIP_IGMP
+ }
+ #endif
+ 
 #if LWIP_DHCP
   /* Pass DHCP messages regardless of destination address. DHCP traffic is addressed
    * using link layer addressing (such as Ethernet MAC) so we must not filter on IP.
@@ -310,7 +329,13 @@ ip_input(struct pbuf *p, struct netif *inp) {
   }
 
 #if IP_OPTIONS == 0 /* no support for IP options in the IP header? */
+
+#if LWIP_IGMP
+  /* there is an extra "router alert" option in IGMP messages which we allow for but do not police */
+  if((iphdrlen > IP_HLEN &&  (IPH_PROTO(iphdr) != IP_PROTO_IGMP)) {
+#else
   if (iphdrlen > IP_HLEN) {
+#endif
     LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since there were IP options (while IP_OPTIONS == 0).\n"));
     pbuf_free(p);
     IP_STATS_INC(ip.opterr);
@@ -349,6 +374,11 @@ ip_input(struct pbuf *p, struct netif *inp) {
     snmp_inc_ipindelivers();
     icmp_input(p, inp);
     break;
+#if LWIP_IGMP
+  case IP_PROTO_IGMP:
+    igmp_input(p,inp,&(iphdr->dest));
+    break;
+#endif
   default:
     /* send ICMP destination protocol unreachable unless is was a broadcast */
     if (!ip_addr_isbroadcast(&(iphdr->dest), inp) &&
diff --git a/src/include/lwip/api.h b/src/include/lwip/api.h
index 905afbb5..5472307e 100644
--- a/src/include/lwip/api.h
+++ b/src/include/lwip/api.h
@@ -71,6 +71,13 @@ enum netconn_evt {
   NETCONN_EVT_SENDMINUS
 };
 
+#if LWIP_IGMP
+enum netconn_igmp {
+  NETCONN_JOIN,
+  NETCONN_LEAVE
+};
+#endif /* LWIP_IGMP */
+
 struct netbuf {
   struct pbuf *p, *ptr;
   struct ip_addr *fromaddr;
@@ -155,6 +162,13 @@ err_t             netconn_write   (struct netconn *conn,
            u8_t copy);
 err_t             netconn_close   (struct netconn *conn);
 
+#if LWIP_IGMP
+err_t             netconn_join_leave_group (struct netconn *conn,
+                                            struct ip_addr *multiaddr,
+                                            struct ip_addr *interface,
+                                            u16_t join_or_leave);
+#endif /* LWIP_IGMP */
+
 err_t             netconn_err     (struct netconn *conn);
 
 #endif /* __LWIP_API_H__ */
diff --git a/src/include/lwip/api_msg.h b/src/include/lwip/api_msg.h
index e15ea388..b274cd2b 100644
--- a/src/include/lwip/api_msg.h
+++ b/src/include/lwip/api_msg.h
@@ -59,7 +59,11 @@ enum api_msg_type {
   API_MSG_WRITE,
 
   API_MSG_CLOSE,
-  
+
+#if LWIP_IGMP
+  API_MSG_JOIN_LEAVE,
+#endif /* LWIP_IGMP */
+ 
   API_MSG_MAX
 };
 
diff --git a/src/include/lwip/netif.h b/src/include/lwip/netif.h
index b7737699..4e58e734 100644
--- a/src/include/lwip/netif.h
+++ b/src/include/lwip/netif.h
@@ -126,6 +126,10 @@ struct netif {
   u32_t ifoutnucastpkts;
   u32_t ifoutdiscards;
 #endif
+#if LWIP_IGMP
+  /* This function could be called to add or delete a entry in the multicast filter table of the ethernet MAC.*/
+  err_t (*igmp_mac_filter)( struct netif *netif, struct ip_addr *group, u8_t action);
+#endif
 };
 
 /** The list of network interfaces. */
diff --git a/src/include/lwip/opt.h b/src/include/lwip/opt.h
index 269434c1..375f287f 100644
--- a/src/include/lwip/opt.h
+++ b/src/include/lwip/opt.h
@@ -52,6 +52,7 @@
 #ifndef NO_SYS
 #define NO_SYS                          0
 #endif
+
 /* ---------- Memory options ---------- */
 #ifndef MEM_LIBC_MALLOC
 #define MEM_LIBC_MALLOC                 0
@@ -162,10 +163,7 @@ a lot of data that needs to be copied, this should be set high. */
 #define PBUF_LINK_HLEN                  14
 #endif
 
-
-
 /* ---------- ARP options ---------- */
-
 /** Number of active hardware address, IP address pairs cached */
 #ifndef ARP_TABLE_SIZE
 #define ARP_TABLE_SIZE                  10
@@ -270,13 +268,11 @@ a lot of data that needs to be copied, this should be set high. */
 #endif
 
 /* ---------- ICMP options ---------- */
-
 #ifndef ICMP_TTL
 #define ICMP_TTL                       (IP_DEFAULT_TTL)
 #endif
 
-/* ---------- RAW options ---------- */
-
+/* ---------- RAW options ----------- */
 #ifndef LWIP_RAW
 #define LWIP_RAW                        1
 #endif
@@ -286,7 +282,6 @@ a lot of data that needs to be copied, this should be set high. */
 #endif
 
 /* ---------- DHCP options ---------- */
-
 #ifndef LWIP_DHCP
 #define LWIP_DHCP                       0
 #endif
@@ -317,6 +312,11 @@ a lot of data that needs to be copied, this should be set high. */
 #define SNMP_PRIVATE_MIB                0
 #endif
 
+/* ---------- IGMP options ---------- */
+#ifndef LWIP_IGMP
+#define LWIP_IGMP                       0
+#endif
+
 /* ---------- UDP options ---------- */
 #ifndef LWIP_UDP
 #define LWIP_UDP                        1
@@ -516,7 +516,6 @@ a lot of data that needs to be copied, this should be set high. */
 #endif /* LWIP_STATS */
 
 /* ---------- PPP options ---------- */
-
 #ifndef PPP_SUPPORT
 #define PPP_SUPPORT                     0      /* Set for PPP */
 #endif
@@ -764,5 +763,3 @@ a lot of data that needs to be copied, this should be set high. */
 
 #endif /* __LWIP_OPT_H__ */
 
-
-
diff --git a/src/include/lwip/sockets.h b/src/include/lwip/sockets.h
index 16af3832..bdcd724c 100644
--- a/src/include/lwip/sockets.h
+++ b/src/include/lwip/sockets.h
@@ -123,10 +123,26 @@ struct linger {
 /*
  * Options for level IPPROTO_IP
  */
-#define IP_TOS       1
-#define IP_TTL       2
+#define IP_TOS             1
+#define IP_TTL             2
 
 
+#ifdef LWIP_IGMP
+/*
+ * Options and types for UDP multicast traffic handling
+ */
+#define IP_ADD_MEMBERSHIP  3
+#define IP_DROP_MEMBERSHIP 4
+#define IP_MULTICAST_TTL   5
+#define IP_MULTICAST_IF    6
+#define IP_MULTICAST_LOOP  7
+
+typedef struct ip_mreq {
+    struct in_addr imr_multiaddr; /* IP multicast address of group */
+    struct in_addr imr_interface; /* local IP address of interface */
+} ip_mreq;
+#endif /* LWIP_IGMP */
+
 #define IPTOS_TOS_MASK          0x1E
 #define IPTOS_TOS(tos)          ((tos) & IPTOS_TOS_MASK)
 #define IPTOS_LOWDELAY          0x10