diff --git a/components/lwip/lwip/src/core/pbuf.c b/components/lwip/lwip/src/core/pbuf.c
index 059f83a5..67d9b449 100644
--- a/components/lwip/lwip/src/core/pbuf.c
+++ b/components/lwip/lwip/src/core/pbuf.c
@@ -282,7 +282,12 @@ pbuf_alloc(pbuf_layer layer, u16_t length, pbuf_type type)
   switch (type) {
   case PBUF_POOL:
     /* allocate head of pbuf chain into p */
+#ifdef ESP_LWIP
+      /* Only DRAM data can be sent by low-level WIFI */
+    p = (struct pbuf *)memp_malloc_ll(MEMP_PBUF_POOL);
+#else
     p = (struct pbuf *)memp_malloc(MEMP_PBUF_POOL);
+#endif
     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloc: allocated pbuf %p\n", (void *)p));
     if (p == NULL) {
       PBUF_POOL_IS_EMPTY();
@@ -315,7 +320,12 @@ pbuf_alloc(pbuf_layer layer, u16_t length, pbuf_type type)
     rem_len = length - p->len;
     /* any remaining pbufs to be allocated? */
     while (rem_len > 0) {
+#ifdef ESP_LWIP
+      /* Only DRAM data can be sent by low-level WIFI */
+      q = (struct pbuf *)memp_malloc_ll(MEMP_PBUF_POOL);
+#else
       q = (struct pbuf *)memp_malloc(MEMP_PBUF_POOL);
+#endif
       if (q == NULL) {
         PBUF_POOL_IS_EMPTY();
         /* free chain so far allocated */
@@ -357,9 +367,14 @@ pbuf_alloc(pbuf_layer layer, u16_t length, pbuf_type type)
       if (alloc_len < LWIP_MEM_ALIGN_SIZE(length)) {
         return NULL;
       }
-    
+
       /* If pbuf is to be allocated in RAM, allocate memory for it. */
+#ifdef ESP_LWIP
+      /* Only DRAM data can be sent by low-level WIFI */
+      p = (struct pbuf*)mem_malloc_ll(alloc_len);
+#else
       p = (struct pbuf*)mem_malloc(alloc_len);
+#endif
     }
 
     if (p == NULL) {
diff --git a/components/lwip/port/esp8266/freertos/heap.c b/components/lwip/port/esp8266/freertos/heap.c
new file mode 100644
index 00000000..bae921cd
--- /dev/null
+++ b/components/lwip/port/esp8266/freertos/heap.c
@@ -0,0 +1,55 @@
+// Copyright 2018-2019 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <stddef.h>
+#include "lwip/opt.h"
+#include "lwip/memp.h"
+#include "FreeRTOS.h"
+#include "esp8266/eagle_soc.h"
+
+#ifdef ESP_LWIP
+/*
+ * @brief allocate an only DRAM memory block for LWIP pbuf
+ * 
+ * @param s memory size
+ * 
+ * @return memory block pointer
+ */
+void *mem_malloc_ll(size_t s)
+{
+    void *p;
+    void *return_addr = (void *)__builtin_return_address(0);
+
+    p = pvPortMalloc_trace(s, return_addr, (unsigned)-1, false);
+    if (IS_IRAM(p)) {
+        vPortFree_trace(p, return_addr, (unsigned)-1);
+        p = NULL;
+    }
+
+    return p;
+}
+
+void *memp_malloc_ll(size_t type)
+{
+    extern const struct memp_desc* const memp_pools[MEMP_MAX];
+
+    uint8_t *p;
+    const struct memp_desc *desc = memp_pools[type];
+
+    p = (uint8_t *)mem_malloc_ll(MEMP_SIZE + MEMP_ALIGN_SIZE(desc->size));
+
+    return p + MEMP_SIZE;
+}
+
+#endif
diff --git a/components/lwip/port/esp8266/include/lwipopts.h b/components/lwip/port/esp8266/include/lwipopts.h
index 9e0dbfff..7bd39f1d 100644
--- a/components/lwip/port/esp8266/include/lwipopts.h
+++ b/components/lwip/port/esp8266/include/lwipopts.h
@@ -50,6 +50,8 @@
 #include "esp_libc.h"
 #include "esp_system.h"
 
+#define ESP_LWIP 1
+
 #ifdef CONFIG_LWIP_SOCKET_MULTITHREAD
 #define SOCKETS_MT
 #endif
@@ -194,12 +196,32 @@
  */
 #define MEM_LIBC_MALLOC                 1
 
+#ifdef ESP_LWIP
+/*
+ * @brief allocate an only DRAM memory block for LWIP pbuf
+ * 
+ * @param s memory size
+ * 
+ * @return memory block pointer
+ */
+void *mem_malloc_ll(size_t s);
+
+/*
+ * @brief allocate an only DRAM memory pool for LWIP pbuf
+ * 
+ * @param type memory type
+ * 
+ * @return memory pool pointer
+ */
+void *memp_malloc_ll(size_t type);
+#endif
+
 /**
  * Use DRAM instead of IRAM
  */
-#define mem_clib_free os_free
-#define mem_clib_malloc os_malloc
-#define mem_clib_calloc os_calloc
+#define mem_clib_free free
+#define mem_clib_malloc malloc
+#define mem_clib_calloc calloc
 
 /**
  * MEMP_MEM_MALLOC==1: Use mem_malloc/mem_free instead of the lwip pool allocator.
diff --git a/components/lwip/port/esp8266/netif/ethernetif.c b/components/lwip/port/esp8266/netif/ethernetif.c
index 5f140846..ae4abfe3 100644
--- a/components/lwip/port/esp8266/netif/ethernetif.c
+++ b/components/lwip/port/esp8266/netif/ethernetif.c
@@ -89,7 +89,7 @@ static inline struct pbuf *ethernetif_transform_pbuf(struct pbuf *pbuf)
 {
     struct pbuf *p;
 
-    if (!(pbuf->flags & PBUF_FLAG_IS_CUSTOM)) {
+    if (!(pbuf->flags & PBUF_FLAG_IS_CUSTOM) && IS_DRAM(pbuf->payload)) {
         /*
          * Add ref to pbuf to avoid it to be freed by upper layer.
          */
@@ -101,6 +101,12 @@ static inline struct pbuf *ethernetif_transform_pbuf(struct pbuf *pbuf)
     if (!p)
         return NULL;
 
+    if (IS_IRAM(p->payload)) {
+        LWIP_DEBUGF(NETIF_DEBUG, ("low_level_output: data in IRAM\n"));
+        pbuf_free(p);
+        return NULL;
+    }
+
     memcpy(p->payload, pbuf->payload, pbuf->len);
 
     /*
@@ -147,12 +153,7 @@ static int8_t low_level_output(struct netif* netif, struct pbuf* p)
     p = ethernetif_transform_pbuf(p);
     if (!p) {
         LWIP_DEBUGF(NETIF_DEBUG, ("low_level_output: lack memory\n"));
-        goto exit; // return ERR_OK
-    }
-
-    if (IS_IRAM(p->payload)) {
-        LWIP_DEBUGF(NETIF_DEBUG, ("low_level_output: data in IRAM\n"));
-        goto error; // return ERR_OK
+        return ERR_OK;
     }
 
     aio.fd = (int)netif->state;
@@ -171,11 +172,9 @@ static int8_t low_level_output(struct netif* netif, struct pbuf* p)
         if (err == ERR_MEM)
             err = ERR_OK;
 
-        goto error;
+        pbuf_free(p);
     }
 
-    return ERR_OK;
-
 //  signal that packet should be sent();
 
 #if ETH_PAD_SIZE
@@ -185,9 +184,6 @@ static int8_t low_level_output(struct netif* netif, struct pbuf* p)
 #if LWIP_STATS
     LINK_STATS_INC(link.xmit);
 #endif
-error:
-    pbuf_free(p);
-exit:
     return err;
 }