diff --git a/boards.txt b/boards.txt
index 1519bba24..af080f735 100644
--- a/boards.txt
+++ b/boards.txt
@@ -1680,7 +1680,7 @@ coredev.build.lwip_flags=
 
 coredev.menu.LwIPVariant.Espressif=Espressif (xcc)
 coredev.menu.LwIPVariant.Espressif.build.lwip_lib=-llwip
-coredev.menu.LwIPVariant.Espressif.build.lwip_flags=
+coredev.menu.LwIPVariant.Espressif.build.lwip_flags=-DLWIP_MAYBE_XCC
 coredev.menu.LwIPVariant.Prebuilt=Prebuilt Source (gcc)
 coredev.menu.LwIPVariant.Prebuilt.build.lwip_lib=-llwip_gcc
 coredev.menu.LwIPVariant.Prebuilt.build.lwip_flags=-DLWIP_OPEN_SRC
diff --git a/libraries/ESP8266WiFi/src/include/UdpContext.h b/libraries/ESP8266WiFi/src/include/UdpContext.h
index c367492cd..9213accfe 100644
--- a/libraries/ESP8266WiFi/src/include/UdpContext.h
+++ b/libraries/ESP8266WiFi/src/include/UdpContext.h
@@ -44,11 +44,11 @@ public:
     , _tx_buf_head(0)
     , _tx_buf_cur(0)
     , _tx_buf_offset(0)
-    , _multicast_ttl(1)
-    , _dest_port(0)
     {
         _pcb = udp_new();
-        _dest_addr.addr = 0;
+#ifdef LWIP_MAYBE_XCC
+        _mcast_ttl = 1;
+#endif
     }
 
     ~UdpContext()
@@ -87,8 +87,8 @@ public:
 
     bool connect(ip_addr_t addr, uint16_t port)
     {
-        _dest_addr = addr;
-        _dest_port = port;
+        ip_addr_copy(_pcb->remote_ip, addr);
+        _pcb->remote_port = port;
         return true;
     }
 
@@ -106,17 +106,16 @@ public:
 
     void setMulticastInterface(ip_addr_t addr)
     {
-        // newer versions of lwip have a macro to set the multicast ip
-        // udp_set_multicast_netif_addr(_pcb, addr);
-        _pcb->multicast_ip = addr;
+        udp_set_multicast_netif_addr(_pcb, addr);
     }
 
     void setMulticastTTL(int ttl)
     {
-        // newer versions of lwip have an additional field (mcast_ttl) for this purpose
-        // and a macro to set it instead of direct field access
-        // udp_set_multicast_ttl(_pcb, ttl);
-        _multicast_ttl = ttl;
+#ifdef LWIP_MAYBE_XCC
+        _mcast_ttl = ttl;
+#else
+        udp_set_multicast_ttl(_pcb, ttl);
+#endif
     }
 
     // warning: handler is called from tcp stack context
@@ -275,20 +274,22 @@ public:
 
 
         if (!addr) {
-            addr = &_dest_addr;
-            port = _dest_port;
+            addr = &_pcb->remote_ip;
+            port = _pcb->remote_port;
         }
-
+#ifdef LWIP_MAYBE_XCC
         uint16_t old_ttl = _pcb->ttl;
         if (ip_addr_ismulticast(addr)) {
-            _pcb->ttl = _multicast_ttl;
+            _pcb->ttl = _mcast_ttl;
         }
-
+#endif
         err_t err = udp_sendto(_pcb, tx_copy, addr, port);
         if (err != ERR_OK) {
             DEBUGV(":ust rc=%d\r\n", err);
         }
+#ifdef LWIP_MAYBE_XCC
         _pcb->ttl = old_ttl;
+#endif
         pbuf_free(tx_copy);
         return err == ERR_OK;
     }
@@ -365,10 +366,10 @@ private:
     pbuf* _tx_buf_head;
     pbuf* _tx_buf_cur;
     size_t _tx_buf_offset;
-    uint16_t _multicast_ttl;
-    uint16_t _dest_port;
-    ip_addr_t _dest_addr;
     rxhandler_t _on_rx;
+#ifdef LWIP_MAYBE_XCC
+    uint16_t _mcast_ttl;
+#endif
 };
 
 
diff --git a/tools/sdk/lib/liblwip_gcc.a b/tools/sdk/lib/liblwip_gcc.a
index 6006179d8..f1cfed0d3 100644
Binary files a/tools/sdk/lib/liblwip_gcc.a and b/tools/sdk/lib/liblwip_gcc.a differ
diff --git a/tools/sdk/lwip/include/lwip/tcp_impl.h b/tools/sdk/lwip/include/lwip/tcp_impl.h
index 24ca8bb95..f6778700a 100644
--- a/tools/sdk/lwip/include/lwip/tcp_impl.h
+++ b/tools/sdk/lwip/include/lwip/tcp_impl.h
@@ -1,8 +1,8 @@
 /*
  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
- * All rights reserved. 
- * 
- * Redistribution and use in source and binary forms, with or without modification, 
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright notice,
@@ -11,21 +11,21 @@
  *    this list of conditions and the following disclaimer in the documentation
  *    and/or other materials provided with the distribution.
  * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission. 
+ *    derived from this software without specific prior written permission.
  *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  * OF SUCH DAMAGE.
  *
  * This file is part of the lwIP TCP/IP stack.
- * 
+ *
  * Author: Adam Dunkels <adam@sics.se>
  *
  */
@@ -284,7 +284,7 @@ struct tcp_seg {
   u16_t oversize_left;     /* Extra bytes available at the end of the last
                               pbuf in unsent (used for asserting vs.
                               tcp_pcb.unsent_oversized only) */
-#endif /* TCP_OVERSIZE_DBGCHECK */ 
+#endif /* TCP_OVERSIZE_DBGCHECK */
 #if TCP_CHECKSUM_ON_COPY
   u16_t chksum;
   u8_t  chksum_swapped;
@@ -313,7 +313,7 @@ extern u32_t tcp_ticks;
 
 /* The TCP PCB lists. */
 union tcp_listen_pcbs_t { /* List of all TCP PCBs in LISTEN state. */
-  struct tcp_pcb_listen *listen_pcbs; 
+  struct tcp_pcb_listen *listen_pcbs;
   struct tcp_pcb *pcbs;
 };
 extern struct tcp_pcb *tcp_bound_pcbs;
@@ -325,7 +325,7 @@ extern struct tcp_pcb *tcp_tw_pcbs;      /* List of all TCP PCBs in TIME-WAIT. *
 
 extern struct tcp_pcb *tcp_tmp_pcb;      /* Only used for temporary storage. */
 
-/* Axioms about the above lists:   
+/* Axioms about the above lists:
    1) Every TCP PCB that is not CLOSED is in one of the lists.
    2) A PCB is only in one of the lists.
    3) All PCBs in the tcp_listen_pcbs list is in LISTEN state.
@@ -396,6 +396,26 @@ extern struct tcp_pcb *tcp_tmp_pcb;      /* Only used for temporary storage. */
 
 #endif /* LWIP_DEBUG */
 
+#define TCP_TW_LIMIT(l)                                   \
+  do {                                                    \
+    u32_t tcp_tmp_pcbs_count = 0;                         \
+    tcp_tmp_pcb = tcp_tw_pcbs;                            \
+    while(tcp_tmp_pcb != NULL) {                          \
+      if(++tcp_tmp_pcbs_count == (l)) {                   \
+        struct tcp_pcb *_tcp_tmp_pcb = tcp_tmp_pcb->next; \
+        tcp_tmp_pcb->next = NULL;                         \
+        tcp_tmp_pcb = _tcp_tmp_pcb;                       \
+        while(tcp_tmp_pcb != NULL) {                      \
+          _tcp_tmp_pcb = tcp_tmp_pcb;                     \
+          tcp_pcb_purge(tcp_tmp_pcb);                     \
+          tcp_tmp_pcb = tcp_tmp_pcb->next;                \
+          memp_free(MEMP_TCP_PCB, _tcp_tmp_pcb);          \
+        }                                                 \
+        break;                                            \
+      }                                                   \
+      tcp_tmp_pcb = tcp_tmp_pcb->next;                    \
+    }                                                     \
+  } while(0)
 
 /* Internal functions: */
 struct tcp_pcb *tcp_pcb_copy(struct tcp_pcb *pcb)ICACHE_FLASH_ATTR;
diff --git a/tools/sdk/lwip/include/lwip/udp.h b/tools/sdk/lwip/include/lwip/udp.h
index cb53d33e7..2e4b57ae7 100644
--- a/tools/sdk/lwip/include/lwip/udp.h
+++ b/tools/sdk/lwip/include/lwip/udp.h
@@ -1,8 +1,8 @@
 /*
  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
- * All rights reserved. 
- * 
- * Redistribution and use in source and binary forms, with or without modification, 
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright notice,
@@ -11,21 +11,21 @@
  *    this list of conditions and the following disclaimer in the documentation
  *    and/or other materials provided with the distribution.
  * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission. 
+ *    derived from this software without specific prior written permission.
  *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  * OF SUCH DAMAGE.
  *
  * This file is part of the lwIP TCP/IP stack.
- * 
+ *
  * Author: Adam Dunkels <adam@sics.se>
  *
  */
@@ -103,6 +103,10 @@ struct udp_pcb {
 #if LWIP_IGMP
   /** outgoing network interface for multicast packets */
   ip_addr_t multicast_ip;
+#ifndef LWIP_MAYBE_XCC
+  /** TTL for outgoing multicast packets */
+  u8_t mcast_ttl;
+#endif /* LWIP_MAYBE_XCC */
 #endif /* LWIP_IGMP */
 
 #if LWIP_UDPLITE
@@ -113,7 +117,7 @@ struct udp_pcb {
   /** receive callback function */
   udp_recv_fn recv;
   /** user-supplied argument for the recv callback */
-  void *recv_arg;  
+  void *recv_arg;
 };
 /* udp_pcbs export for exernal reference (e.g. SNMP agent) */
 extern struct udp_pcb *udp_pcbs;
@@ -156,6 +160,15 @@ void             udp_input      (struct pbuf *p, struct netif *inp)ICACHE_FLASH_
 
 #define udp_init() /* Compatibility define, not init needed. */
 
+#if LWIP_IGMP
+#define udp_set_multicast_netif_addr(pcb, ipaddr)  ip_addr_copy((pcb)->multicast_ip, (ipaddr))
+#define udp_get_multicast_netif_addr(pcb)          ((pcb)->multicast_ip)
+#ifndef LWIP_MAYBE_XCC
+#define udp_set_multicast_ttl(pcb, value)      do { (pcb)->mcast_ttl = value; } while(0)
+#define udp_get_multicast_ttl(pcb)                 ((pcb)->mcast_ttl)
+#endif /* LWIP_MAYBE_XCC */
+#endif /* LWIP_IGMP */
+
 #if UDP_DEBUG
 void udp_debug_print(struct udp_hdr *udphdr)ICACHE_FLASH_ATTR;
 #else
diff --git a/tools/sdk/lwip/include/lwipopts.h b/tools/sdk/lwip/include/lwipopts.h
index c163ac625..2081b3aea 100644
--- a/tools/sdk/lwip/include/lwipopts.h
+++ b/tools/sdk/lwip/include/lwipopts.h
@@ -6,9 +6,9 @@
 
 /*
  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
- * All rights reserved. 
- * 
- * Redistribution and use in source and binary forms, with or without modification, 
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright notice,
@@ -17,21 +17,21 @@
  *    this list of conditions and the following disclaimer in the documentation
  *    and/or other materials provided with the distribution.
  * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission. 
+ *    derived from this software without specific prior written permission.
  *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  * OF SUCH DAMAGE.
  *
  * This file is part of the lwIP TCP/IP stack.
- * 
+ *
  * Author: Adam Dunkels <adam@sics.se>
  *
  */
@@ -56,7 +56,7 @@
 #define SYS_LIGHTWEIGHT_PROT            0
 #endif
 
-/** 
+/**
  * NO_SYS==1: Provides VERY minimal functionality. Otherwise,
  * use lwIP facilities.
  */
@@ -179,8 +179,8 @@
 /**
  * MEMP_USE_CUSTOM_POOLS==1: whether to include a user file lwippools.h
  * that defines additional pools beyond the "standard" ones required
- * by lwIP. If you set this to 1, you must have lwippools.h in your 
- * inlude path somewhere. 
+ * by lwIP. If you set this to 1, you must have lwippools.h in your
+ * inlude path somewhere.
  */
 #ifndef MEMP_USE_CUSTOM_POOLS
 #define MEMP_USE_CUSTOM_POOLS           0
@@ -255,6 +255,14 @@
 #define MEMP_NUM_TCP_PCB_LISTEN         2
 #endif
 
+/**
+ * MEMP_NUM_TCP_PCB_TIME_WAIT: the number of TCP pcbs in TIME_WAIT state.
+ * (requires the LWIP_TCP option, 0 = disabled)
+ */
+#ifndef MEMP_NUM_TCP_PCB_TIME_WAIT
+#define MEMP_NUM_TCP_PCB_TIME_WAIT       5
+#endif
+
 /**
  * MEMP_NUM_TCP_SEG: the number of simultaneously queued TCP segments.
  * (requires the LWIP_TCP option)
@@ -328,7 +336,7 @@
 
 /**
  * MEMP_NUM_TCPIP_MSG_API: the number of struct tcpip_msg, which are used
- * for callback/timeout API communication. 
+ * for callback/timeout API communication.
  * (only needed if you use tcpip.c)
  */
 #ifndef MEMP_NUM_TCPIP_MSG_API
@@ -337,7 +345,7 @@
 
 /**
  * MEMP_NUM_TCPIP_MSG_INPKT: the number of struct tcpip_msg, which are used
- * for incoming packets. 
+ * for incoming packets.
  * (only needed if you use tcpip.c)
  */
 #ifndef MEMP_NUM_TCPIP_MSG_INPKT
@@ -402,7 +410,7 @@
 #endif
 
 /**
- * PBUF_POOL_SIZE: the number of buffers in the pbuf pool. 
+ * PBUF_POOL_SIZE: the number of buffers in the pbuf pool.
  */
 #ifndef PBUF_POOL_SIZE
 #define PBUF_POOL_SIZE                  10
@@ -714,7 +722,7 @@
 
 /**
  * SNMP_CONCURRENT_REQUESTS: Number of concurrent requests the module will
- * allow. At least one request buffer is required. 
+ * allow. At least one request buffer is required.
  */
 #ifndef SNMP_CONCURRENT_REQUESTS
 #define SNMP_CONCURRENT_REQUESTS        0
@@ -729,7 +737,7 @@
 #endif
 
 /**
- * SNMP_PRIVATE_MIB: 
+ * SNMP_PRIVATE_MIB:
  */
 #ifndef SNMP_PRIVATE_MIB
 #define SNMP_PRIVATE_MIB                0
@@ -775,7 +783,7 @@
    ----------------------------------
 */
 /**
- * LWIP_IGMP==1: Turn on IGMP module. 
+ * LWIP_IGMP==1: Turn on IGMP module.
  */
 #ifndef LWIP_IGMP
 #define LWIP_IGMP                       1
@@ -903,12 +911,12 @@
 #endif
 
 /**
- * TCP_WND: The size of a TCP window.  This must be at least 
+ * TCP_WND: The size of a TCP window.  This must be at least
  * (2 * TCP_MSS) for things to work well
  */
 #ifndef TCP_WND
 #define TCP_WND                         (*(volatile uint32*)0x600011F0)
-#endif 
+#endif
 
 /**
  * TCP_MAXRTX: Maximum number of retransmissions of data segments.
@@ -973,7 +981,7 @@
 
 
 /**
- * TCP_SND_BUF: TCP sender buffer space (bytes). 
+ * TCP_SND_BUF: TCP sender buffer space (bytes).
  */
 #ifndef TCP_SND_BUF
 #define TCP_SND_BUF                     2 * TCP_MSS
@@ -1064,7 +1072,7 @@
 #ifndef LWIP_EVENT_API
 #define LWIP_EVENT_API                  0
 #define LWIP_CALLBACK_API               1
-#else 
+#else
 #define LWIP_EVENT_API                  1
 #define LWIP_CALLBACK_API               0
 #endif
@@ -1762,28 +1770,28 @@
 #ifndef CHECKSUM_GEN_IP
 #define CHECKSUM_GEN_IP                 1
 #endif
- 
+
 /**
  * CHECKSUM_GEN_UDP==1: Generate checksums in software for outgoing UDP packets.
  */
 #ifndef CHECKSUM_GEN_UDP
 #define CHECKSUM_GEN_UDP                1
 #endif
- 
+
 /**
  * CHECKSUM_GEN_TCP==1: Generate checksums in software for outgoing TCP packets.
  */
 #ifndef CHECKSUM_GEN_TCP
 #define CHECKSUM_GEN_TCP                1
 #endif
- 
+
 /**
  * CHECKSUM_CHECK_IP==1: Check checksums in software for incoming IP packets.
  */
 #ifndef CHECKSUM_CHECK_IP
 #define CHECKSUM_CHECK_IP               1
 #endif
- 
+
 /**
  * CHECKSUM_CHECK_UDP==1: Check checksums in software for incoming UDP packets.
  */
diff --git a/tools/sdk/lwip/src/Makefile b/tools/sdk/lwip/src/Makefile
index e03fda331..5f65751bd 100644
--- a/tools/sdk/lwip/src/Makefile
+++ b/tools/sdk/lwip/src/Makefile
@@ -28,5 +28,8 @@ all: $(LWIP_LIB)
 install: all
 	cp -f $(LWIP_LIB) $(SDK_PATH)/lib/$(LWIP_LIB)
 
+release: all
+	cp -f $(LWIP_LIB) $(SDK_PATH)/lib/liblwip_gcc.a
+
 clean:
 	@rm -rf $(BUILD_PATH) $(LWIP_LIB)
diff --git a/tools/sdk/lwip/src/core/tcp.c b/tools/sdk/lwip/src/core/tcp.c
index ee50cebd7..a3651c61d 100644
--- a/tools/sdk/lwip/src/core/tcp.c
+++ b/tools/sdk/lwip/src/core/tcp.c
@@ -10,9 +10,9 @@
 
 /*
  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
- * All rights reserved. 
- * 
- * Redistribution and use in source and binary forms, with or without modification, 
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright notice,
@@ -21,21 +21,21 @@
  *    this list of conditions and the following disclaimer in the documentation
  *    and/or other materials provided with the distribution.
  * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission. 
+ *    derived from this software without specific prior written permission.
  *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  * OF SUCH DAMAGE.
  *
  * This file is part of the lwIP TCP/IP stack.
- * 
+ *
  * Author: Adam Dunkels <adam@sics.se>
  *
  */
@@ -61,17 +61,17 @@ static const char mem_debug_file[] ICACHE_RODATA_ATTR = __FILE__;
 
 #if TCP_DEBUG
 const char tcp_state_str_rodata[][12] ICACHE_RODATA_ATTR = {
-  "CLOSED",      
-  "LISTEN",      
-  "SYN_SENT",    
-  "SYN_RCVD",    
-  "ESTABLISHED", 
-  "FIN_WAIT_1",  
-  "FIN_WAIT_2",  
-  "CLOSE_WAIT",  
-  "CLOSING",     
-  "LAST_ACK",    
-  "TIME_WAIT"   
+  "CLOSED",
+  "LISTEN",
+  "SYN_SENT",
+  "SYN_RCVD",
+  "ESTABLISHED",
+  "FIN_WAIT_1",
+  "FIN_WAIT_2",
+  "CLOSE_WAIT",
+  "CLOSING",
+  "LAST_ACK",
+  "TIME_WAIT"
 };
 
 char tcp_state_str[12];
@@ -105,7 +105,7 @@ struct tcp_pcb ** const tcp_pcb_lists[] ICACHE_RODATA_ATTR = {&tcp_listen_pcbs.p
 /** Only used for temporary storage. */
 struct tcp_pcb *tcp_tmp_pcb;
 
-/** Timer counter to handle calling slow-timer from tcp_tmr() */ 
+/** Timer counter to handle calling slow-timer from tcp_tmr() */
 static u8_t tcp_timer;
 static u16_t tcp_new_port(void);//����µ�tcp���ض˿�
 
@@ -166,7 +166,9 @@ tcp_close_shutdown(struct tcp_pcb *pcb, u8_t rst_on_unacked_data)
       TCP_RMV(&tcp_active_pcbs, pcb);
       pcb->state = TIME_WAIT;
       TCP_REG(&tcp_tw_pcbs, pcb);
-
+#if MEMP_NUM_TCP_PCB_TIME_WAIT
+      TCP_TW_LIMIT(MEMP_NUM_TCP_PCB_TIME_WAIT);
+#endif
       return ERR_OK;
     }
   }
@@ -177,24 +179,24 @@ tcp_close_shutdown(struct tcp_pcb *pcb, u8_t rst_on_unacked_data)
      * however, it is in this state once allocated and as yet unused
      * and the user needs some way to free it should the need arise.
      * Calling tcp_close() with a pcb that has already been closed, (i.e. twice)
-     * or for a pcb that has been used and then entered the CLOSED state 
+     * or for a pcb that has been used and then entered the CLOSED state
      * is erroneous, but this should never happen as the pcb has in those cases
      * been freed, and so any remaining handles are bogus. */
-     /*��CLOSED״̬�¹ر�һ��pcb�ƺ��Ǵ���ģ� 
-     *������ˣ�һ�������״̬�·����˶��һ�û��ʹ��,�û���ҪһЩ�취���ͷ��� 
-     *����һ���Ѿ����رյ�pcb��tcp_close(),(��2��)����һ���Ѿ���ʹ����֮�󣬽���CLOSE״̬�Ǵ���� 
-     *������Щ����±��ͷŵ�pcb�Dz�����ڵ�,��ˣ��κ�ʣ��ľ���Ǽٵ� 
-     */  
-    err = ERR_OK;//�趨����ֵ 
+     /*��CLOSED״̬�¹ر�һ��pcb�ƺ��Ǵ���ģ�
+     *������ˣ�һ�������״̬�·����˶��һ�û��ʹ��,�û���ҪһЩ�취���ͷ���
+     *����һ���Ѿ����رյ�pcb��tcp_close(),(��2��)����һ���Ѿ���ʹ����֮�󣬽���CLOSE״̬�Ǵ����
+     *������Щ����±��ͷŵ�pcb�Dz�����ڵ�,��ˣ��κ�ʣ��ľ���Ǽٵ�
+     */
+    err = ERR_OK;//�趨����ֵ
     if (pcb->local_port != 0) {
-    	TCP_RMV(&tcp_bound_pcbs, pcb); 
+    	TCP_RMV(&tcp_bound_pcbs, pcb);
     }
     memp_free(MEMP_TCP_PCB, pcb);//��MEMP_TCP_PCB�ڴ���趨�ͷŵ���pcb��Ӧ�ĵ�Ԫֵ,�ͷ��ڴ�
     pcb = NULL;
     break;
   case LISTEN:
     err = ERR_OK;
-    tcp_pcb_remove(&tcp_listen_pcbs.pcbs, pcb);//�Ӽ����PCB�б���ɾ���Ӧ��pcb  
+    tcp_pcb_remove(&tcp_listen_pcbs.pcbs, pcb);//�Ӽ����PCB�б���ɾ���Ӧ��pcb
     memp_free(MEMP_TCP_PCB_LISTEN, pcb);//��MEMP_TCP_PCB_LISTEN�ڴ�����趨�ͷŵ�pcb��Ԫֵ  ,�ͷ��ڴ�
     pcb = NULL;
     break;
@@ -261,14 +263,14 @@ tcp_close_shutdown(struct tcp_pcb *pcb, u8_t rst_on_unacked_data)
  * @return ERR_OK if connection has been closed
  *         another err_t if closing failed and pcb is not freed
  */
- /* 
- *ͨ��PCB�ر��������� 
- *�����е�pcbӦ�ñ��ͷŵģ�Ҳ����ԶҲ���ᱻʹ���� 
- *���û�����ӻ�����Ҳû�б�����,���ӵ�pcbӦ�ñ��ͷŵ� 
- *���һ�����ӱ�����(����SYN�Ѿ������ջ�����һ���ر��е�״̬) 
- *���ӱ��ر��ˣ�����������һ�����ڹرյ�״̬ 
- *pcb�Զ���tcp_slowtmr()�ͷ�,�����������Dz���ȫ�� 
- */ 
+ /*
+ *ͨ��PCB�ر���������
+ *�����е�pcbӦ�ñ��ͷŵģ�Ҳ����ԶҲ���ᱻʹ����
+ *���û�����ӻ�����Ҳû�б�����,���ӵ�pcbӦ�ñ��ͷŵ�
+ *���һ�����ӱ�����(����SYN�Ѿ������ջ�����һ���ر��е�״̬)
+ *���ӱ��ر��ˣ�����������һ�����ڹرյ�״̬
+ *pcb�Զ���tcp_slowtmr()�ͷ�,�����������Dz���ȫ��
+ */
 err_t
 tcp_close(struct tcp_pcb *pcb)
 {
@@ -341,7 +343,7 @@ tcp_abandon(struct tcp_pcb *pcb, int reset)
   u32_t seqno, ackno;
   u16_t remote_port, local_port;
   ip_addr_t remote_ip, local_ip;
-#if LWIP_CALLBACK_API  
+#if LWIP_CALLBACK_API
   tcp_err_fn errf;
 #endif /* LWIP_CALLBACK_API */
   void *errf_arg;
@@ -373,7 +375,7 @@ tcp_abandon(struct tcp_pcb *pcb, int reset)
     if (pcb->unsent != NULL) {
       tcp_segs_free(pcb->unsent);
     }
-#if TCP_QUEUE_OOSEQ    
+#if TCP_QUEUE_OOSEQ
     if (pcb->ooseq != NULL) {
       tcp_segs_free(pcb->ooseq);
     }
@@ -555,7 +557,7 @@ tcp_listen_with_backlog(struct tcp_pcb *pcb, u8_t backlog)
   return (struct tcp_pcb *)lpcb;
 }
 
-/** 
+/**
  * Update the state that tracks the available window space to advertise.
  *
  * Returns how much extra window would be advertised if we sent an
@@ -636,7 +638,7 @@ tcp_new_port(void)
 #define TCP_LOCAL_PORT_RANGE_END   0x7fff
 #endif
   static u16_t port = TCP_LOCAL_PORT_RANGE_START;
-  
+
  again:
 //  if (++port >= TCP_LOCAL_PORT_RANGE_END) {
 //    port = TCP_LOCAL_PORT_RANGE_START;
@@ -646,7 +648,7 @@ tcp_new_port(void)
   if (port < TCP_LOCAL_PORT_RANGE_START)
 	  port += TCP_LOCAL_PORT_RANGE_START;
   /* Check all PCB lists. */
-  for (i = 0; i < NUM_TCP_PCB_LISTS; i++) {  
+  for (i = 0; i < NUM_TCP_PCB_LISTS; i++) {
     for(pcb = *tcp_pcb_lists[i]; pcb != NULL; pcb = pcb->next) {
       if (pcb->local_port == port) {
         goto again;
@@ -743,7 +745,7 @@ tcp_connect(struct tcp_pcb *pcb, ip_addr_t *ipaddr, u16_t port,
   pcb->ssthresh = pcb->mss * 10;
 #if LWIP_CALLBACK_API
   pcb->connected = connected;//ע��connected�ص�����
-#else /* LWIP_CALLBACK_API */  
+#else /* LWIP_CALLBACK_API */
   LWIP_UNUSED_ARG(connected);
 #endif /* LWIP_CALLBACK_API */
 
@@ -849,7 +851,7 @@ tcp_slowtmr(void)
           LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_slowtmr: cwnd %"U16_F
                                        " ssthresh %"U16_F"\n",
                                        pcb->cwnd, pcb->ssthresh));
- 
+
           /* The following needs to be called AFTER cwnd is set to one
              mss - STJ */
           tcp_rexmit_rto(pcb);
@@ -873,7 +875,7 @@ tcp_slowtmr(void)
       if((u32_t)(tcp_ticks - pcb->tmr) >
          (pcb->keep_idle + (pcb->keep_cnt*pcb->keep_intvl))
          / TCP_SLOW_INTERVAL)
-#else      
+#else
       if((u32_t)(tcp_ticks - pcb->tmr) >
          (pcb->keep_idle + TCP_MAXIDLE) / TCP_SLOW_INTERVAL)
 #endif /* LWIP_TCP_KEEPALIVE */
@@ -881,17 +883,17 @@ tcp_slowtmr(void)
         LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: KEEPALIVE timeout. Aborting connection to %"U16_F".%"U16_F".%"U16_F".%"U16_F".\n",
                                 ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
                                 ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip)));
-        
+
         ++pcb_remove;
         ++pcb_reset;
       }
 #if LWIP_TCP_KEEPALIVE
-      else if((u32_t)(tcp_ticks - pcb->tmr) > 
+      else if((u32_t)(tcp_ticks - pcb->tmr) >
               (pcb->keep_idle + pcb->keep_cnt_sent * pcb->keep_intvl)
               / TCP_SLOW_INTERVAL)
 #else
-      else if((u32_t)(tcp_ticks - pcb->tmr) > 
-              (pcb->keep_idle + pcb->keep_cnt_sent * TCP_KEEPINTVL_DEFAULT) 
+      else if((u32_t)(tcp_ticks - pcb->tmr) >
+              (pcb->keep_idle + pcb->keep_cnt_sent * TCP_KEEPINTVL_DEFAULT)
               / TCP_SLOW_INTERVAL)
 #endif /* LWIP_TCP_KEEPALIVE */
       {
@@ -942,12 +944,12 @@ tcp_slowtmr(void)
         LWIP_ASSERT("tcp_slowtmr: first pcb == tcp_active_pcbs", tcp_active_pcbs == pcb);
         tcp_active_pcbs = pcb->next;
       }
-      
+
       if (pcb_reset) {
         tcp_rst(pcb->snd_nxt, pcb->rcv_nxt, &pcb->local_ip, &pcb->remote_ip,
           pcb->local_port, pcb->remote_port);
       }
-	  
+
 	  TCP_EVENT_ERR(pcb->errf, pcb->callback_arg, ERR_ABRT);
       pcb2 = pcb;
       pcb = pcb->next;
@@ -971,7 +973,7 @@ tcp_slowtmr(void)
     }
   }
 
-  
+
   /* Steps through all of the TIME-WAIT PCBs. */
   prev = NULL;
   pcb = tcp_tw_pcbs;
@@ -983,7 +985,7 @@ tcp_slowtmr(void)
     if ((u32_t)(tcp_ticks - pcb->tmr) > 2 * TCP_MSL / TCP_SLOW_INTERVAL) {
       ++pcb_remove;
     }
-    
+
 
 
     /* If the PCB should be removed, do it. */
@@ -1101,7 +1103,7 @@ tcp_setprio(struct tcp_pcb *pcb, u8_t prio)
  *
  * @param seg the old tcp_seg
  * @return a copy of seg
- */ 
+ */
 struct tcp_seg *
 tcp_seg_copy(struct tcp_seg *seg)
 {
@@ -1111,7 +1113,7 @@ tcp_seg_copy(struct tcp_seg *seg)
   if (cseg == NULL) {
     return NULL;
   }
-  SMEMCPY((u8_t *)cseg, (const u8_t *)seg, sizeof(struct tcp_seg)); 
+  SMEMCPY((u8_t *)cseg, (const u8_t *)seg, sizeof(struct tcp_seg));
   pbuf_ref(cseg->p);
   return cseg;
 }
@@ -1150,7 +1152,7 @@ tcp_kill_prio(u8_t prio)
 
 
   mprio = TCP_PRIO_MAX;
-  
+
   /* We kill the oldest active connection that has lower priority than prio. */
   inactivity = 0;
   inactive = NULL;
@@ -1207,7 +1209,7 @@ tcp_alloc(u8_t prio)
 {
   struct tcp_pcb *pcb;
   u32_t iss;
-  
+
   pcb = (struct tcp_pcb *)memp_malloc(MEMP_TCP_PCB);//�����ڴ�ؿռ�
   if (pcb == NULL) {
 	//os_printf("tcp_pcb memory is fail\n");
@@ -1253,18 +1255,18 @@ tcp_alloc(u8_t prio)
     pcb->snd_wl2 = iss;										//��ʼ�����ʹ��ڸ����ֶ�
     pcb->snd_nxt = iss;
     pcb->lastack = iss;
-    pcb->snd_lbb = iss;   
+    pcb->snd_lbb = iss;
     pcb->tmr = tcp_ticks;										//��¼���ƿ鴴��ϵͳʱ��
 
     pcb->polltmr = 0;										//����������¼���ʱ��
 
 #if LWIP_CALLBACK_API
     pcb->recv = tcp_recv_null;								//ע�������ݵ�Ĭ���ϲ㺯��
-#endif /* LWIP_CALLBACK_API */  
-    
+#endif /* LWIP_CALLBACK_API */
+
     /* Init KEEPALIVE timer */
     pcb->keep_idle  = TCP_KEEPIDLE_DEFAULT;
-    
+
 #if LWIP_TCP_KEEPALIVE
     pcb->keep_intvl = TCP_KEEPINTVL_DEFAULT;
     pcb->keep_cnt   = TCP_KEEPCNT_DEFAULT;
@@ -1300,10 +1302,10 @@ tcp_new(void)
 * ���ֶν���Ϊ����ݸ��������
  * @param pcb tcp_pcb to set the callback argument
  * @param arg void pointer argument to pass to callback functions
- */ 
+ */
 void
 tcp_arg(struct tcp_pcb *pcb, void *arg)
-{  
+{
   pcb->callback_arg = arg;
 }
 #if LWIP_CALLBACK_API
@@ -1314,7 +1316,7 @@ tcp_arg(struct tcp_pcb *pcb, void *arg)
  *����ƿ��recv�ֶ�ע�ắ���յ����ʱ�ص�
  * @param pcb tcp_pcb to set the recv callback
  * @param recv callback function to call for this pcb when data is received
- */ 
+ */
 void
 tcp_recv(struct tcp_pcb *pcb, tcp_recv_fn recv)
 {
@@ -1327,7 +1329,7 @@ tcp_recv(struct tcp_pcb *pcb, tcp_recv_fn recv)
  *����ƿ�send �ֶ�ע�ắ����ݷ��ͳɹ���ص�
  * @param pcb tcp_pcb to set the sent callback
  * @param sent callback function to call for this pcb when data is successfully sent
- */ 
+ */
 void
 tcp_sent(struct tcp_pcb *pcb, tcp_sent_fn sent)
 {
@@ -1341,7 +1343,7 @@ tcp_sent(struct tcp_pcb *pcb, tcp_sent_fn sent)
  * @param pcb tcp_pcb to set the err callback
  * @param err callback function to call for this pcb when a fatal error
  *        has occured on the connection
- */ 
+ */
 void
 tcp_err(struct tcp_pcb *pcb, tcp_err_fn err)
 {
@@ -1355,7 +1357,7 @@ tcp_err(struct tcp_pcb *pcb, tcp_err_fn err)
  * @param pcb tcp_pcb to set the accept callback
  * @param accept callback function to call for this pcb when LISTENing
  *        connection has been connected to another host
- */ 
+ */
 void
 tcp_accept(struct tcp_pcb *pcb, tcp_accept_fn accept)
 {
@@ -1369,15 +1371,15 @@ tcp_accept(struct tcp_pcb *pcb, tcp_accept_fn accept)
  * from TCP. The interval is specified in terms of the TCP coarse
  * timer interval, which is called twice a second.
  *����ƿ��POLL�ֶ�ע�ắ��ú��������Ա�����
- */ 
+ */
 void
 tcp_poll(struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval)
 {
 #if LWIP_CALLBACK_API
   pcb->poll = poll;
-#else /* LWIP_CALLBACK_API */  
+#else /* LWIP_CALLBACK_API */
   LWIP_UNUSED_ARG(poll);
-#endif /* LWIP_CALLBACK_API */  
+#endif /* LWIP_CALLBACK_API */
   pcb->pollinterval = interval;
 }
 
@@ -1461,7 +1463,7 @@ tcp_pcb_remove(struct tcp_pcb **pcblist, struct tcp_pcb *pcb)
   TCP_RMV(pcblist, pcb);
 
   tcp_pcb_purge(pcb);
-  
+
   /* if there is an outstanding delayed ACKs, send it */
   if (pcb->state != TIME_WAIT &&
      pcb->state != LISTEN &&
@@ -1492,7 +1494,7 @@ u32_t
 tcp_next_iss(void)
 {
   static u32_t iss = 6510;
-  
+
   again:
     iss += tcp_ticks;       /* XXX */
     if (iss == 0)
@@ -1632,21 +1634,21 @@ tcp_debug_print_pcbs(void)
                        pcb->local_port, pcb->remote_port,
                        pcb->snd_nxt, pcb->rcv_nxt));
     tcp_debug_print_state(pcb->state);
-  }    
+  }
   LWIP_DEBUGF(TCP_DEBUG, ("Listen PCB states:\n"));
   for(pcb = (struct tcp_pcb *)tcp_listen_pcbs.pcbs; pcb != NULL; pcb = pcb->next) {
     LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ",
                        pcb->local_port, pcb->remote_port,
                        pcb->snd_nxt, pcb->rcv_nxt));
     tcp_debug_print_state(pcb->state);
-  }    
+  }
   LWIP_DEBUGF(TCP_DEBUG, ("TIME-WAIT PCB states:\n"));
   for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next) {
     LWIP_DEBUGF(TCP_DEBUG, ("Local port %"U16_F", foreign port %"U16_F" snd_nxt %"U32_F" rcv_nxt %"U32_F" ",
                        pcb->local_port, pcb->remote_port,
                        pcb->snd_nxt, pcb->rcv_nxt));
     tcp_debug_print_state(pcb->state);
-  }    
+  }
 }
 
 /**
diff --git a/tools/sdk/lwip/src/core/tcp_in.c b/tools/sdk/lwip/src/core/tcp_in.c
index be74a28ac..409559605 100644
--- a/tools/sdk/lwip/src/core/tcp_in.c
+++ b/tools/sdk/lwip/src/core/tcp_in.c
@@ -6,7 +6,7 @@
  *
  * These functions are generally called in the order (ip_input() ->)
  * tcp_input() -> * tcp_process() -> tcp_receive() (-> application).
- * 
+ *
  */
 
 /*
@@ -92,12 +92,12 @@ static err_t tcp_timewait_input(struct tcp_pcb *pcb)ICACHE_FLASH_ATTR;
  * @param p received TCP segment to process (p->payload pointing to the IP header)
  * @param inp network interface on which this segment was received
  */
- /** 
- *  TCP��ʼ�����봦�?��֤��TCPͷ���������IP����� 
- 
- * @����p:������յ�TCP��(ָ��IPͷ�ĸ���) 
- * @����inp:���նε�����ӿ� 
- */ 
+ /**
+ *  TCP��ʼ�����봦�?��֤��TCPͷ���������IP�����
+
+ * @����p:������յ�TCP��(ָ��IPͷ�ĸ���)
+ * @����inp:���նε�����ӿ�
+ */
 void
 tcp_input(struct pbuf *p, struct netif *inp)
 {
@@ -112,15 +112,15 @@ tcp_input(struct pbuf *p, struct netif *inp)
 
   PERF_START;
 
-  TCP_STATS_INC(tcp.recv);	//״̬��1 
+  TCP_STATS_INC(tcp.recv);	//״̬��1
   snmp_inc_tcpinsegs();			//tcp����μ�1
 
   iphdr = (struct ip_hdr *)p->payload;// pointer to the actual data in the buffer
-  /* 
-  *��ͷ����(IHL)��4λ��IPЭ���ͷ�ij��ȣ�ָ��IPv4Э���ͷ���ȵ��ֽ������ٸ�32λ�� 
-  *����IPv4�İ�ͷ���ܰ�ɱ������Ŀ�ѡ ���������ֶο�������ȷ��IPv4��ݱ�����ݲ��ֵ�ƫ������ 
-  *IPv4��ͷ����С������20���ֽڣ����IHL����ֶε���Сֵ��ʮ���Ʊ�ʾ����5 (5x4 = 20�ֽ�)�� 
-  *����˵�����ʾ�İ�ͷ�����ֽ�����4�ֽڵı���  
+  /*
+  *��ͷ����(IHL)��4λ��IPЭ���ͷ�ij��ȣ�ָ��IPv4Э���ͷ���ȵ��ֽ������ٸ�32λ��
+  *����IPv4�İ�ͷ���ܰ�ɱ������Ŀ�ѡ ���������ֶο�������ȷ��IPv4��ݱ�����ݲ��ֵ�ƫ������
+  *IPv4��ͷ����С������20���ֽڣ����IHL����ֶε���Сֵ��ʮ���Ʊ�ʾ����5 (5x4 = 20�ֽ�)��
+  *����˵�����ʾ�İ�ͷ�����ֽ�����4�ֽڵı���
   */
   tcphdr = (struct tcp_hdr *)((u8_t *)p->payload + IPH_HL(iphdr) * 4);
 
@@ -135,7 +135,7 @@ tcp_input(struct pbuf *p, struct netif *inp)
     TCP_STATS_INC(tcp.lenerr);//���󳤶ȼ���
     TCP_STATS_INC(tcp.drop);//��ֹ����
     snmp_inc_tcpinerrs();
-    pbuf_free(p);//�ͷ�buffer 
+    pbuf_free(p);//�ͷ�buffer
     return;
   }
 
@@ -183,23 +183,23 @@ tcp_input(struct pbuf *p, struct netif *inp)
   /* Convert fields in TCP header to host byte order. */
   tcphdr->src = ntohs(tcphdr->src);				//ת��Դ��ַ
   tcphdr->dest = ntohs(tcphdr->dest);				//ת��Ŀ�ĵ�ַ
-  seqno = tcphdr->seqno = ntohl(tcphdr->seqno);	//ת�����к� 
+  seqno = tcphdr->seqno = ntohl(tcphdr->seqno);	//ת�����к�
   ackno = tcphdr->ackno = ntohl(tcphdr->ackno);	//ת��Ӧ���
   tcphdr->wnd = ntohs(tcphdr->wnd);				//ת��tcp����
 
-  flags = TCPH_FLAGS(tcphdr);//�õ�tcp header�ı�־ 
-  /* 
-  *��־��3λ�����ֶΣ��� 
-  *    ����λ��1λ 
-  *    ���ֶ�λ��1λ��ȡֵ��0��������ݱ��ֶΣ���1����ݱ����ֶܷΣ� 
-  *    ����λ��1λ��ȡֵ��0����ݰ����û�а�1����ݰ�����и��İ� 
-  */ 
+  flags = TCPH_FLAGS(tcphdr);//�õ�tcp header�ı�־
+  /*
+  *��־��3λ�����ֶΣ���
+  *    ����λ��1λ
+  *    ���ֶ�λ��1λ��ȡֵ��0��������ݱ��ֶΣ���1����ݱ����ֶܷΣ�
+  *    ����λ��1λ��ȡֵ��0����ݰ����û�а�1����ݰ�����и��İ�
+  */
   tcplen = p->tot_len + ((flags & (TCP_FIN | TCP_SYN)) ? 1 : 0);//TCP_FIN �� TCP_SYN ���1�������0
 
   /* Demultiplex an incoming segment. First, we check if it is destined
      for an active connection. ���ȣ�����Ƿ�һ��Ҫ����һ������*/
  ////////////////////////////////////////////////////////////////////////////////////////
-  prev = NULL;  
+  prev = NULL;
   for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next) {//������б�
     LWIP_ASSERT("tcp_input: active pcb->state != CLOSED", pcb->state != CLOSED);
     LWIP_ASSERT("tcp_input: active pcb->state != TIME-WAIT", pcb->state != TIME_WAIT);
@@ -286,9 +286,9 @@ tcp_input(struct pbuf *p, struct netif *inp)
               /* put this listening pcb at the head of the listening list */
         tcp_listen_pcbs.listen_pcbs = lpcb;
       }
-    
+
       LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_input: packed for LISTENing connection.\n"));
-      tcp_listen_input(lpcb);//����tcp������ݰ� 
+      tcp_listen_input(lpcb);//����tcp������ݰ�
       pbuf_free(p);
       return;
     }
@@ -385,7 +385,7 @@ tcp_input(struct pbuf *p, struct netif *inp)
 	//PSH��־ PSH ����λ��
 	//��PSH=1ʱ��Ҫ���ͷ����Ϸ��͸÷ֶΣ�
 	//����շ�����Ľ����Ľ���Ӧ�ò㣬�������д��?
-		  
+
           if (flags & TCP_PSH) {
             recv_data->flags |= PBUF_FLAG_PUSH;//���bufferӦ������������
           }
@@ -411,7 +411,7 @@ tcp_input(struct pbuf *p, struct netif *inp)
           if (pcb->rcv_wnd != TCP_WND) {
             pcb->rcv_wnd++;
           }
-	 
+
           TCP_EVENT_CLOSED(pcb, err);
           if (err == ERR_ABRT) {
             goto aborted;
@@ -595,21 +595,21 @@ tcp_listen_input(struct tcp_pcb_listen *pcb)
 static err_t
 tcp_timewait_input(struct tcp_pcb *pcb)
 {
-  
+
   if (flags & TCP_RST)  {		//RST��λ��ֱ�ӷ���
     return ERR_OK;
   }
- 
+
   if (flags & TCP_SYN) {		//��SYN������Ϣ����������ݱ���ڽ��մ����ڣ����ͷ�����RST����
- 
+
     if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, pcb->rcv_nxt+pcb->rcv_wnd)) {
-      
+
       tcp_rst(ackno, seqno + tcplen, ip_current_dest_addr(), ip_current_src_addr(),
         tcphdr->dest, tcphdr->src);
       return ERR_OK;
     }
   } else if (flags & TCP_FIN) {	//���İ�FIN������Ϣ
-  						    
+
     pcb->tmr = tcp_ticks;		  	//��λ�ȴ�2MSLʱ�䣬���ƿ����µȴ�2MSL
   }
 
@@ -648,7 +648,7 @@ tcp_process(struct tcp_pcb *pcb)
         acceptable = 1;
       }
     } else {
-      if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, 
+      if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
                           pcb->rcv_nxt+pcb->rcv_wnd)) {
         acceptable = 1;
       }
@@ -669,12 +669,12 @@ tcp_process(struct tcp_pcb *pcb)
     }
   }
 
-  if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) { 
+  if ((flags & TCP_SYN) && (pcb->state != SYN_SENT && pcb->state != SYN_RCVD)) {
     /* Cope with new connection attempt after remote end crashed */
     tcp_ack_now(pcb);
     return ERR_OK;
   }
-  
+
   if ((pcb->flags & TF_RXCLOSED) == 0) {
     /* Update the PCB (in)activity timer unless rx is closed (see tcp_shutdown) */
     pcb->tmr = tcp_ticks;
@@ -808,6 +808,9 @@ tcp_process(struct tcp_pcb *pcb)
         TCP_RMV(&tcp_active_pcbs, pcb);
         pcb->state = TIME_WAIT;
         TCP_REG(&tcp_tw_pcbs, pcb);
+  #if MEMP_NUM_TCP_PCB_TIME_WAIT
+        TCP_TW_LIMIT(MEMP_NUM_TCP_PCB_TIME_WAIT);
+  #endif
       } else {
         tcp_ack_now(pcb);
         pcb->state = CLOSING;
@@ -825,6 +828,9 @@ tcp_process(struct tcp_pcb *pcb)
       TCP_RMV(&tcp_active_pcbs, pcb);
       pcb->state = TIME_WAIT;
       TCP_REG(&tcp_tw_pcbs, pcb);
+#if MEMP_NUM_TCP_PCB_TIME_WAIT
+      TCP_TW_LIMIT(MEMP_NUM_TCP_PCB_TIME_WAIT);
+#endif
     }
     break;
   case CLOSING:
@@ -835,6 +841,9 @@ tcp_process(struct tcp_pcb *pcb)
       TCP_RMV(&tcp_active_pcbs, pcb);
       pcb->state = TIME_WAIT;
       TCP_REG(&tcp_tw_pcbs, pcb);
+#if MEMP_NUM_TCP_PCB_TIME_WAIT
+      TCP_TW_LIMIT(MEMP_NUM_TCP_PCB_TIME_WAIT);
+#endif
     }
     break;
   case LAST_ACK:
@@ -939,7 +948,7 @@ tcp_receive(struct tcp_pcb *pcb)
 #if TCP_WND_DEBUG
     } else {
       if (pcb->snd_wnd != tcphdr->wnd) {
-        LWIP_DEBUGF(TCP_WND_DEBUG, 
+        LWIP_DEBUGF(TCP_WND_DEBUG,
                     ("tcp_receive: no window update lastack %"U32_F" ackno %"
                      U32_F" wl1 %"U32_F" seqno %"U32_F" wl2 %"U32_F"\n",
                      pcb->lastack, ackno, pcb->snd_wl1, seqno, pcb->snd_wl2));
@@ -954,12 +963,12 @@ tcp_receive(struct tcp_pcb *pcb)
      * 3) the advertised window hasn't changed ���ش���û�и���
      * 4) There is outstanding unacknowledged data (retransmission timer running)������ݵȴ�ȷ��
      * 5) The ACK is == biggest ACK sequence number so far seen (snd_una)   ackno = lastack
-     * 
-     * If it passes all five, should process as a dupack: 
-     * a) dupacks < 3: do nothing 
-     * b) dupacks == 3: fast retransmit 
-     * c) dupacks > 3: increase cwnd 
-     * 
+     *
+     * If it passes all five, should process as a dupack:
+     * a) dupacks < 3: do nothing
+     * b) dupacks == 3: fast retransmit
+     * c) dupacks > 3: increase cwnd
+     *
      * If it only passes 1-3, should reset dupack counter (and add to
      * stats, which we don't do in lwIP)
      *
@@ -1002,10 +1011,10 @@ tcp_receive(struct tcp_pcb *pcb)
       }
     } else if (TCP_SEQ_BETWEEN(ackno, pcb->lastack+1, pcb->snd_nxt)){//ackno��lastack+1��snd_nxt֮�䣬�жϷ��ʹ��������
       /* We come here when the ACK acknowledges new data. */
-	  
+
       if (pcb->flags & TF_INFR) {
         pcb->flags &= ~TF_INFR;// Reset the "IN Fast Retransmit" flag,since we are no longer in fast retransmit
-        pcb->cwnd = pcb->ssthresh;//Reset the congestion window to the  "slow start threshold".       
+        pcb->cwnd = pcb->ssthresh;//Reset the congestion window to the  "slow start threshold".
       }
 
       /* Reset the number of retransmissions. */
@@ -1047,7 +1056,7 @@ tcp_receive(struct tcp_pcb *pcb)
                                     ntohl(pcb->unacked->tcphdr->seqno) + TCP_TCPLEN(pcb->unacked): 0));
 
       /* Remove segment from the unacknowledged list if the incoming
-         ACK acknowlegdes them. 
+         ACK acknowlegdes them.
          *�ͷ�unacked�����ϱ�ȷ�ϵı��ĶΣ�
          *ֱ��unacked����Ϊ��ֹͣ*/
       while (pcb->unacked != NULL &&
@@ -1068,7 +1077,7 @@ tcp_receive(struct tcp_pcb *pcb)
           pcb->acked--;
         }
 
-        pcb->snd_queuelen -= pbuf_clen(next->p);//�������������pbufs���� 
+        pcb->snd_queuelen -= pbuf_clen(next->p);//�������������pbufs����
         tcp_seg_free(next);//�ͷ�tcp��
 
         LWIP_DEBUGF(TCP_QLEN_DEBUG, ("%"U16_F" (after freeing unacked)\n", (u16_t)pcb->snd_queuelen));
@@ -1099,13 +1108,13 @@ tcp_receive(struct tcp_pcb *pcb)
        in fact have been sent once. */
        /** unsent�������Ƿ��ܱ�acknoȷ�ϵı��ĶΣ������ͷ�**/
     while (pcb->unsent != NULL &&
-           TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) + 
+           TCP_SEQ_BETWEEN(ackno, ntohl(pcb->unsent->tcphdr->seqno) +
                            TCP_TCPLEN(pcb->unsent), pcb->snd_nxt)) {
       LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_receive: removing %"U32_F":%"U32_F" from pcb->unsent\n",
                                     ntohl(pcb->unsent->tcphdr->seqno), ntohl(pcb->unsent->tcphdr->seqno) +
                                     TCP_TCPLEN(pcb->unsent)));
 
-      next = pcb->unsent;//pcbδ���ͱ�־ 
+      next = pcb->unsent;//pcbδ���ͱ�־
       pcb->unsent = pcb->unsent->next;//δ���͵���һ��
       LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"U16_F" ... ", (u16_t)pcb->snd_queuelen));
       LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
@@ -1252,7 +1261,7 @@ tcp_receive(struct tcp_pcb *pcb)
     /* The sequence number must be within the window (above rcv_nxt
        and below rcv_nxt + rcv_wnd) in order to be further
        processed. */
-    if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt, 
+    if (TCP_SEQ_BETWEEN(seqno, pcb->rcv_nxt,
                         pcb->rcv_nxt + pcb->rcv_wnd - 1)){//rcv_nxt <  seqno < rcv_nxt + rcv_wnd - 1,������ڽ��շ�Χ��
       if (pcb->rcv_nxt == seqno) {
         /* The incoming segment is the next in sequence. We check if
@@ -1261,12 +1270,12 @@ tcp_receive(struct tcp_pcb *pcb)
         tcplen = TCP_TCPLEN(&inseg);//���㱨�Ķγ���
 
         if (tcplen > pcb->rcv_wnd) {//������մ��ڴ�С��������β���ض�
-          LWIP_DEBUGF(TCP_INPUT_DEBUG, 
+          LWIP_DEBUGF(TCP_INPUT_DEBUG,
                       ("tcp_receive: other end overran receive window"
                        "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
                        seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
           if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
-            /* Must remove the FIN from the header as we're trimming 
+            /* Must remove the FIN from the header as we're trimming
              * that byte of sequence-space from the packet */
             TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) &~ TCP_FIN);
           }
@@ -1286,7 +1295,7 @@ tcp_receive(struct tcp_pcb *pcb)
            - inseq overlaps with ooseq */
         if (pcb->ooseq != NULL) {
           if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
-            LWIP_DEBUGF(TCP_INPUT_DEBUG, 
+            LWIP_DEBUGF(TCP_INPUT_DEBUG,
                         ("tcp_receive: received in-order FIN, binning ooseq queue\n"));
             /* Received in-order FIN means anything that was received
              * out of order must now have been received in-order, so
@@ -1394,7 +1403,7 @@ tcp_receive(struct tcp_pcb *pcb)
             recv_flags |= TF_GOT_FIN;
             if (pcb->state == ESTABLISHED) { /* force passive close or we can move to active close */
               pcb->state = CLOSE_WAIT;
-            } 
+            }
           }
 
           pcb->ooseq = cseg->next;
@@ -1507,12 +1516,12 @@ tcp_receive(struct tcp_pcb *pcb)
                   }
                   /* check if the remote side overruns our receive window */
                   if ((u32_t)tcplen + seqno > pcb->rcv_nxt + (u32_t)pcb->rcv_wnd) {
-                    LWIP_DEBUGF(TCP_INPUT_DEBUG, 
+                    LWIP_DEBUGF(TCP_INPUT_DEBUG,
                                 ("tcp_receive: other end overran receive window"
                                  "seqno %"U32_F" len %"U16_F" right edge %"U32_F"\n",
                                  seqno, tcplen, pcb->rcv_nxt + pcb->rcv_wnd));
                     if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
-                      /* Must remove the FIN from the header as we're trimming 
+                      /* Must remove the FIN from the header as we're trimming
                        * that byte of sequence-space from the packet */
                       TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) &~ TCP_FIN);
                     }
@@ -1549,7 +1558,7 @@ tcp_receive(struct tcp_pcb *pcb)
 }
 
 /**
- * Parses the options contained in the incoming segment. 
+ * Parses the options contained in the incoming segment.
  *
  * Called from tcp_listen_input() and tcp_process().
  * Currently, only the MSS option is supported!
@@ -1606,7 +1615,7 @@ tcp_parseopt(struct tcp_pcb *pcb)
           return;
         }
         /* TCP timestamp option with valid length */
-        tsval = (opts[c+2]) | (opts[c+3] << 8) | 
+        tsval = (opts[c+2]) | (opts[c+3] << 8) |
           (opts[c+4] << 16) | (opts[c+5] << 24);
         if (flags & TCP_SYN) {
           pcb->ts_recent = ntohl(tsval);
diff --git a/tools/sdk/lwip/src/core/udp.c b/tools/sdk/lwip/src/core/udp.c
index db12c48e9..42539d6d7 100644
--- a/tools/sdk/lwip/src/core/udp.c
+++ b/tools/sdk/lwip/src/core/udp.c
@@ -144,7 +144,7 @@ udp_input(struct pbuf *p, struct netif *inp)
     /* all packets for DHCP_CLIENT_PORT not coming from DHCP_SERVER_PORT are dropped! */
     if (src == DHCP_SERVER_PORT) {
       if ((inp->dhcp != NULL) && (inp->dhcp->pcb != NULL)) {
-        /* accept the packe if 
+        /* accept the packe if
            (- broadcast or directed to us) -> DHCP is link-layer-addressed, local ip is always ANY!
            - inp->dhcp->pcb->remote == ANY or iphdr->src */
         if ((ip_addr_isany(&inp->dhcp->pcb->remote_ip) ||
@@ -196,7 +196,7 @@ udp_input(struct pbuf *p, struct netif *inp)
            (broadcast))) {
 #endif /* IP_SOF_BROADCAST_RECV */
         local_match = 1;
-        if ((uncon_pcb == NULL) && 
+        if ((uncon_pcb == NULL) &&
             ((pcb->flags & UDP_FLAGS_CONNECTED) == 0)) {
           /* the first unconnected matching PCB */
           uncon_pcb = pcb;
@@ -422,7 +422,7 @@ udp_send_chksum(struct udp_pcb *pcb, struct pbuf *p,
  *
  * If the PCB already has a remote address association, it will
  * be restored after the data is sent.
- * 
+ *
  * @return lwIP error code (@see udp_send for possible error codes)
  *
  * @see udp_disconnect() udp_send()
@@ -504,6 +504,7 @@ udp_sendto_if_chksum(struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *dst_ip,
   ip_addr_t *src_ip;
   err_t err;
   struct pbuf *q; /* q will be sent down the stack */
+  u8_t ttl;
 
 #if IP_SOF_BROADCAST
   /* broadcast filter? */
@@ -553,11 +554,11 @@ udp_sendto_if_chksum(struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *dst_ip,
   udphdr->src = htons(pcb->local_port);
   udphdr->dest = htons(dst_port);
   /* in UDP, 0 checksum means 'no checksum' */
-  udphdr->chksum = 0x0000; 
+  udphdr->chksum = 0x0000;
 
   /* Multicast Loop? */
 #if LWIP_IGMP
-  if (ip_addr_ismulticast(dst_ip) && ((pcb->flags & UDP_FLAGS_MULTICAST_LOOP) != 0)) {
+  if (((pcb->flags & UDP_FLAGS_MULTICAST_LOOP) != 0) && ip_addr_ismulticast(dst_ip)) {
     q->flags |= PBUF_FLAG_MCASTLOOP;
   }
 #endif /* LWIP_IGMP */
@@ -665,13 +666,21 @@ udp_sendto_if_chksum(struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *dst_ip,
       udphdr->chksum = udpchksum;
     }
 #endif /* CHECKSUM_GEN_UDP */
+
+  /* Determine TTL to use */
+#if LWIP_IGMP
+    ttl = (ip_addr_ismulticast(dst_ip) ? pcb->mcast_ttl : pcb->ttl);
+#else /* LWIP_IGMP */
+    ttl = pcb->ttl;
+#endif /* LWIP_IGMP */
+
     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP checksum 0x%04"X16_F"\n", udphdr->chksum));
     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: ip_output_if (,,,,IP_PROTO_UDP,)\n"));
     /* output to IP */
 #if LWIP_NETIF_HWADDRHINT
     netif->addr_hint = &(pcb->addr_hint);
 #endif /* LWIP_NETIF_HWADDRHINT*/
-    err = ip_output_if(q, src_ip, dst_ip, pcb->ttl, pcb->tos, IP_PROTO_UDP, netif);
+    err = ip_output_if(q, src_ip, dst_ip, ttl, pcb->tos, IP_PROTO_UDP, netif);
 #if LWIP_NETIF_HWADDRHINT
     netif->addr_hint = NULL;
 #endif /* LWIP_NETIF_HWADDRHINT*/
@@ -950,6 +959,9 @@ udp_new(void)
     /* initialize PCB to all zeroes */
     os_memset(pcb, 0, sizeof(struct udp_pcb));
     pcb->ttl = UDP_TTL;
+#if LWIP_IGMP
+    pcb->mcast_ttl = UDP_TTL;
+#endif
   }
   return pcb;
 }