diff --git a/doc/guides/rel_notes/release_17_08.rst b/doc/guides/rel_notes/release_17_08.rst
index 842f46f..f067247 100644
--- a/doc/guides/rel_notes/release_17_08.rst
+++ b/doc/guides/rel_notes/release_17_08.rst
@@ -75,6 +75,13 @@ New Features
 
   Added support for firmwares with multiple Ethernet ports per physical port.
 
+* **Add Generic Receive Offload API support.**
+
+  Generic Receive Offload (GRO) API supports to reassemble TCP/IPv4
+  packets. GRO API assumes all inputted packets are with correct
+  checksums. GRO API doesn't update checksums for merged packets. If
+  inputted packets are IP fragmented, GRO API assumes they are complete
+  packets (i.e. with L4 headers).
 
 Resolved Issues
 ---------------
diff --git a/lib/librte_gro/Makefile b/lib/librte_gro/Makefile
index 7e0f128..43e276e 100644
--- a/lib/librte_gro/Makefile
+++ b/lib/librte_gro/Makefile
@@ -43,6 +43,7 @@ LIBABIVER := 1
 
 # source files
 SRCS-$(CONFIG_RTE_LIBRTE_GRO) += rte_gro.c
+SRCS-$(CONFIG_RTE_LIBRTE_GRO) += rte_gro_tcp4.c
 
 # install this header file
 SYMLINK-$(CONFIG_RTE_LIBRTE_GRO)-include += rte_gro.h
diff --git a/lib/librte_gro/rte_gro.c b/lib/librte_gro/rte_gro.c
index 648835b..a4641f9 100644
--- a/lib/librte_gro/rte_gro.c
+++ b/lib/librte_gro/rte_gro.c
@@ -32,8 +32,11 @@
 
 #include <rte_malloc.h>
 #include <rte_mbuf.h>
+#include <rte_cycles.h>
+#include <rte_ethdev.h>
 
 #include "rte_gro.h"
+#include "rte_gro_tcp4.h"
 
 typedef void *(*gro_tbl_create_fn)(uint16_t socket_id,
 		uint16_t max_flow_num,
@@ -41,9 +44,12 @@ typedef void *(*gro_tbl_create_fn)(uint16_t socket_id,
 typedef void (*gro_tbl_destroy_fn)(void *tbl);
 typedef uint32_t (*gro_tbl_item_num_fn)(void *tbl);
 
-static gro_tbl_create_fn tbl_create_functions[RTE_GRO_TYPE_MAX_NUM];
-static gro_tbl_destroy_fn tbl_destroy_functions[RTE_GRO_TYPE_MAX_NUM];
-static gro_tbl_item_num_fn tbl_item_num_functions[RTE_GRO_TYPE_MAX_NUM];
+static gro_tbl_create_fn tbl_create_functions[RTE_GRO_TYPE_MAX_NUM] = {
+	gro_tcp4_tbl_create, NULL};
+static gro_tbl_destroy_fn tbl_destroy_functions[RTE_GRO_TYPE_MAX_NUM] = {
+	gro_tcp4_tbl_destroy, NULL};
+static gro_tbl_item_num_fn tbl_item_num_functions[
+	RTE_GRO_TYPE_MAX_NUM] = {gro_tcp4_tbl_item_num, NULL};
 
 /**
  * GRO table, which is used to merge packets. It keeps many reassembly
@@ -130,27 +136,118 @@ void rte_gro_tbl_destroy(void *tbl)
 }
 
 uint16_t
-rte_gro_reassemble_burst(struct rte_mbuf **pkts __rte_unused,
+rte_gro_reassemble_burst(struct rte_mbuf **pkts,
 		uint16_t nb_pkts,
-		const struct rte_gro_param *param __rte_unused)
+		const struct rte_gro_param *param)
 {
-	return nb_pkts;
+	uint16_t i;
+	uint16_t nb_after_gro = nb_pkts;
+	uint32_t item_num;
+
+	/* allocate a reassembly table for TCP/IPv4 GRO */
+	struct gro_tcp4_tbl tcp_tbl;
+	struct gro_tcp4_key tcp_keys[RTE_GRO_MAX_BURST_ITEM_NUM] = {0};
+	struct gro_tcp4_item tcp_items[RTE_GRO_MAX_BURST_ITEM_NUM] = {0};
+
+	struct rte_mbuf *unprocess_pkts[nb_pkts];
+	uint16_t unprocess_num = 0;
+	int32_t ret;
+	uint64_t current_time;
+
+	if ((param->desired_gro_types & RTE_GRO_TCP_IPV4) == 0)
+		return nb_pkts;
+
+	/* get the actual number of items */
+	item_num = RTE_MIN(nb_pkts, (param->max_flow_num *
+			param->max_item_per_flow));
+	item_num = RTE_MIN(item_num, RTE_GRO_MAX_BURST_ITEM_NUM);
+
+	tcp_tbl.keys = tcp_keys;
+	tcp_tbl.items = tcp_items;
+	tcp_tbl.key_num = 0;
+	tcp_tbl.item_num = 0;
+	tcp_tbl.max_key_num = item_num;
+	tcp_tbl.max_item_num = item_num;
+
+	current_time = rte_rdtsc();
+
+	for (i = 0; i < nb_pkts; i++) {
+		if (RTE_ETH_IS_IPV4_HDR(pkts[i]->packet_type) &&
+				(pkts[i]->packet_type & RTE_PTYPE_L4_TCP)) {
+			ret = gro_tcp4_reassemble(pkts[i],
+					&tcp_tbl,
+					param->max_packet_size,
+					current_time);
+			if (ret > 0)
+				/* merge successfully */
+				nb_after_gro--;
+			else if (ret < 0)
+				unprocess_pkts[unprocess_num++] =
+					pkts[i];
+		} else
+			unprocess_pkts[unprocess_num++] =
+				pkts[i];
+	}
+
+	/* re-arrange GROed packets */
+	if (nb_after_gro < nb_pkts) {
+		i = gro_tcp4_tbl_timeout_flush(&tcp_tbl, 0,
+				pkts, nb_pkts);
+		if (unprocess_num > 0)
+			memcpy(&pkts[i], unprocess_pkts,
+					sizeof(struct rte_mbuf *) *
+					unprocess_num);
+	}
+	return nb_after_gro;
 }
 
 uint16_t
-rte_gro_reassemble(struct rte_mbuf **pkts __rte_unused,
+rte_gro_reassemble(struct rte_mbuf **pkts,
 		uint16_t nb_pkts,
-		void *tbl __rte_unused)
+		void *tbl)
 {
-	return nb_pkts;
+	uint16_t i, unprocess_num = 0;
+	struct rte_mbuf *unprocess_pkts[nb_pkts];
+	struct gro_tbl *gro_tbl = (struct gro_tbl *)tbl;
+	uint64_t current_time;
+
+	if ((gro_tbl->desired_gro_types & RTE_GRO_TCP_IPV4) == 0)
+		return nb_pkts;
+
+	current_time = rte_rdtsc();
+	for (i = 0; i < nb_pkts; i++) {
+		if (RTE_ETH_IS_IPV4_HDR(pkts[i]->packet_type) &&
+				(pkts[i]->packet_type & RTE_PTYPE_L4_TCP)) {
+			if (gro_tcp4_reassemble(pkts[i],
+						gro_tbl->tbls[RTE_GRO_TCP_IPV4_INDEX],
+						gro_tbl->max_packet_size,
+						current_time) < 0)
+				unprocess_pkts[unprocess_num++] = pkts[i];
+		} else
+			unprocess_pkts[unprocess_num++] = pkts[i];
+	}
+	if (unprocess_num > 0)
+		memcpy(pkts, unprocess_pkts,
+				sizeof(struct rte_mbuf *) * unprocess_num);
+
+	return unprocess_num;
 }
 
 uint16_t
-rte_gro_timeout_flush(void *tbl __rte_unused,
-		uint64_t desired_gro_types __rte_unused,
-		struct rte_mbuf **out __rte_unused,
-		uint16_t max_nb_out __rte_unused)
+rte_gro_timeout_flush(void *tbl,
+		uint64_t desired_gro_types,
+		struct rte_mbuf **out,
+		uint16_t max_nb_out)
 {
+	struct gro_tbl *gro_tbl = (struct gro_tbl *)tbl;
+
+	desired_gro_types = desired_gro_types &
+		gro_tbl->desired_gro_types;
+	if (desired_gro_types & RTE_GRO_TCP_IPV4)
+		return gro_tcp4_tbl_timeout_flush(
+				gro_tbl->tbls[RTE_GRO_TCP_IPV4_INDEX],
+				gro_tbl->max_timeout_cycles,
+				out, max_nb_out);
 	return 0;
 }
 
diff --git a/lib/librte_gro/rte_gro.h b/lib/librte_gro/rte_gro.h
index 02c9113..68d2fc6 100644
--- a/lib/librte_gro/rte_gro.h
+++ b/lib/librte_gro/rte_gro.h
@@ -45,7 +45,11 @@ extern "C" {
 
 /* max number of supported GRO types */
 #define RTE_GRO_TYPE_MAX_NUM 64
-#define RTE_GRO_TYPE_SUPPORT_NUM 0	/**< current supported GRO num */
+#define RTE_GRO_TYPE_SUPPORT_NUM 1	/**< current supported GRO num */
+
+/* TCP/IPv4 GRO flag */
+#define RTE_GRO_TCP_IPV4_INDEX 0
+#define RTE_GRO_TCP_IPV4 (1ULL << RTE_GRO_TCP_IPV4_INDEX)
 
 
 struct rte_gro_param {
@@ -118,14 +122,14 @@ uint16_t rte_gro_reassemble_burst(struct rte_mbuf **pkts,
  *
  * @param pkts
  *  packet to reassemble. Besides, after this function finishes, it
- *  keeps the unprocessed packets (i.e. without data or unsupported
+ *  keeps the unprocessed packets (e.g. without data or unsupported
  *  GRO types).
  * @param nb_pkts
  *  the number of packets to reassemble.
  * @param tbl
  *  a pointer points to a GRO table.
  * @return
- *  return the number of unprocessed packets (i.e. without data or
+ *  return the number of unprocessed packets (e.g. without data or
  *  unsupported GRO types). If all packets are processed (merged or
  *  inserted into the table), return 0.
  */
diff --git a/lib/librte_gro/rte_gro_tcp4.c b/lib/librte_gro/rte_gro_tcp4.c
new file mode 100644
index 0000000..8f2aa86
--- /dev/null
+++ b/lib/librte_gro/rte_gro_tcp4.c
@@ -0,0 +1,439 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2017 Intel Corporation. All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "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 COPYRIGHT
+ *   OWNER OR CONTRIBUTORS 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.
+ */
+
+#include <rte_malloc.h>
+#include <rte_mbuf.h>
+#include <rte_cycles.h>
+
+#include <rte_ethdev.h>
+#include <rte_ip.h>
+#include <rte_tcp.h>
+
+#include "rte_gro_tcp4.h"
+
+void *gro_tcp4_tbl_create(uint16_t socket_id,
+		uint16_t max_flow_num,
+		uint16_t max_item_per_flow)
+{
+	size_t size;
+	uint32_t entries_num;
+	struct gro_tcp4_tbl *tbl;
+
+	entries_num = max_flow_num * max_item_per_flow;
+	entries_num = entries_num > GRO_TCP4_TBL_MAX_ITEM_NUM ?
+		GRO_TCP4_TBL_MAX_ITEM_NUM : entries_num;
+
+	if (entries_num == 0)
+		return NULL;
+
+	tbl = (struct gro_tcp4_tbl *)rte_zmalloc_socket(
+			__func__,
+			sizeof(struct gro_tcp4_tbl),
+			RTE_CACHE_LINE_SIZE,
+			socket_id);
+	if (tbl == NULL)
+		return NULL;
+
+	size = sizeof(struct gro_tcp4_item) * entries_num;
+	tbl->items = (struct gro_tcp4_item *)rte_zmalloc_socket(
+			__func__,
+			size,
+			RTE_CACHE_LINE_SIZE,
+			socket_id);
+	if (tbl->items == NULL) {
+		rte_free(tbl);
+		return NULL;
+	}
+	tbl->max_item_num = entries_num;
+
+	size = sizeof(struct gro_tcp4_key) * entries_num;
+	tbl->keys = (struct gro_tcp4_key *)rte_zmalloc_socket(
+			__func__,
+			size, RTE_CACHE_LINE_SIZE,
+			socket_id);
+	if (tbl->keys == NULL) {
+		rte_free(tbl->items);
+		rte_free(tbl);
+		return NULL;
+	}
+	tbl->max_key_num = entries_num;
+	return tbl;
+}
+
+void gro_tcp4_tbl_destroy(void *tbl)
+{
+	struct gro_tcp4_tbl *tcp_tbl = (struct gro_tcp4_tbl *)tbl;
+
+	if (tcp_tbl) {
+		rte_free(tcp_tbl->items);
+		rte_free(tcp_tbl->keys);
+	}
+	rte_free(tcp_tbl);
+}
+
+static struct rte_mbuf *get_mbuf_lastseg(struct rte_mbuf *pkt)
+{
+	struct rte_mbuf *lastseg = pkt;
+
+	while (lastseg->next)
+		lastseg = lastseg->next;
+
+	return lastseg;
+}
+
+/**
+ * merge two TCP/IPv4 packets without updating checksums.
+ */
+static int
+merge_two_tcp4_packets(struct gro_tcp4_item *item_src,
+		struct rte_mbuf *pkt,
+		uint32_t max_packet_size,
+		int cmp)
+{
+	struct rte_mbuf *pkt_head, *pkt_tail, *lastseg;
+	struct ipv4_hdr *ipv4_hdr1, *ipv4_hdr0;
+	uint16_t tcp_dl1;
+
+	if (cmp > 0) {
+		/* append the new packet into tail */
+		pkt_head = item_src->pkt;
+		pkt_tail = pkt;
+	} else {
+		/* append the new packet into head */
+		pkt_head = pkt;
+		pkt_tail = item_src->pkt;
+	}
+
+	/* parse the tail packet */
+	ipv4_hdr1 = (struct ipv4_hdr *)(rte_pktmbuf_mtod(pkt_tail,
+				char *) + pkt_tail->l2_len);
+	tcp_dl1 = rte_be_to_cpu_16(ipv4_hdr1->total_length) -
+		pkt_tail->l3_len - pkt_tail->l4_len;
+
+	if (pkt_head->pkt_len + tcp_dl1 > max_packet_size)
+		return -1;
+
+	/* remove packet header for the tail packet */
+	rte_pktmbuf_adj(pkt_tail, pkt_tail->l2_len +
+			pkt_tail->l3_len +
+			pkt_tail->l4_len);
+
+	if (cmp > 0) {
+		/* chain the new packet to the tail of the original packet */
+		item_src->lastseg->next = pkt_tail;
+		/* update the lastseg for the item */
+		item_src->lastseg = get_mbuf_lastseg(pkt_tail);
+	} else {
+		/* chain the original packet to the tail of the new packet */
+		lastseg = get_mbuf_lastseg(pkt_head);
+		lastseg->next = pkt_tail;
+		/* update the item */
+		item_src->pkt = pkt_head;
+	}
+
+	/* parse the head packet */
+	ipv4_hdr0 = (struct ipv4_hdr *)(rte_pktmbuf_mtod(pkt_head,
+				char *) + pkt_head->l2_len);
+
+	/* update IP header for the head packet */
+	ipv4_hdr0->total_length = rte_cpu_to_be_16(
+			rte_be_to_cpu_16(
+				ipv4_hdr0->total_length)
+			+ tcp_dl1);
+	ipv4_hdr0->packet_id = ipv4_hdr1->packet_id;
+
+	/* update mbuf metadata for the merged packet */
+	pkt_head->nb_segs += pkt_tail->nb_segs;
+	pkt_head->pkt_len += pkt_tail->pkt_len;
+	return 1;
+}
+
+static int
+check_seq_option(struct rte_mbuf *pkt,
+		struct tcp_hdr *tcp_hdr,
+		uint16_t ip_id,
+		uint16_t tcp_hl,
+		uint16_t tcp_dl)
+{
+	struct ipv4_hdr *ipv4_hdr0;
+	struct tcp_hdr *tcp_hdr0;
+	uint16_t tcp_hl0, tcp_dl0, ip_id0;
+	uint32_t sent_seq0, sent_seq;
+	uint16_t len;
+
+	ipv4_hdr0 = (struct ipv4_hdr *)(rte_pktmbuf_mtod(pkt,
+				char *) + pkt->l2_len);
+	tcp_hdr0 = (struct tcp_hdr *)((char *)ipv4_hdr0 + pkt->l3_len);
+
+	ip_id0 = rte_be_to_cpu_16(ipv4_hdr0->packet_id);
+	tcp_hl0 = pkt->l4_len;
+	tcp_dl0 = rte_be_to_cpu_16(ipv4_hdr0->total_length) -
+		pkt->l3_len - tcp_hl0;
+
+	/* check if TCP option fields equal. If not, return 0. */
+	len = RTE_MAX(tcp_hl, tcp_hl0) - sizeof(struct tcp_hdr);
+	if ((tcp_hl != tcp_hl0) || ((len > 0) &&
+				(memcmp(tcp_hdr + 1,
+						tcp_hdr0 + 1,
+						len) != 0)))
+		return 0;
+
+	/* check if the two packets are neighbors */
+	sent_seq0 = rte_be_to_cpu_32(tcp_hdr0->sent_seq);
+	sent_seq = rte_be_to_cpu_32(tcp_hdr->sent_seq);
+
+	if ((sent_seq == (sent_seq0 + tcp_dl0)) &&
+			(ip_id == (ip_id0 + 1)))
+		/* append the new packet into tail */
+		return 1;
+	else if (((sent_seq + tcp_dl) == sent_seq0) &&
+		((ip_id + 1) == ip_id0))
+		/* append the new packet into head */
+		return -1;
+	else
+		return 0;
+}
+
+static uint32_t
+find_an_empty_item(struct gro_tcp4_tbl *tbl)
+{
+	uint32_t i;
+
+	for (i = 0; i < tbl->max_item_num; i++)
+		if (tbl->items[i].pkt == NULL)
+			return i;
+	return INVALID_ARRAY_INDEX;
+}
+
+static uint32_t
+find_an_empty_key(struct gro_tcp4_tbl *tbl)
+{
+	uint32_t i;
+
+	for (i = 0; i < tbl->max_key_num; i++)
+		if (tbl->keys[i].is_valid == 0)
+			return i;
+	return INVALID_ARRAY_INDEX;
+}
+
+int32_t
+gro_tcp4_reassemble(struct rte_mbuf *pkt,
+		struct gro_tcp4_tbl *tbl,
+		uint32_t max_packet_size,
+		uint64_t start_time)
+{
+	struct ether_hdr *eth_hdr;
+	struct ipv4_hdr *ipv4_hdr;
+	struct tcp_hdr *tcp_hdr;
+	uint16_t tcp_dl, ip_id;
+
+	struct tcp4_key key;
+	uint32_t cur_idx, prev_idx, item_idx;
+	uint32_t i, key_idx;
+	int cmp;
+
+	eth_hdr = rte_pktmbuf_mtod(pkt, struct ether_hdr *);
+	ipv4_hdr = (struct ipv4_hdr *)((char *)eth_hdr + pkt->l2_len);
+
+	/* check if the packet should be processed */
+	if (pkt->l3_len < sizeof(struct ipv4_hdr))
+		return -1;
+	tcp_hdr = (struct tcp_hdr *)((char *)ipv4_hdr + pkt->l3_len);
+	/* if SYN, FIN, RST, PSH or URG is set, return immediately */
+	if ((tcp_hdr->tcp_flags & (~((uint8_t)TCP_ACK_FLAG))) ||
+			((tcp_hdr->tcp_flags & TCP_ACK_FLAG) == 0))
+		return -1;
+	tcp_dl = rte_be_to_cpu_16(ipv4_hdr->total_length) - pkt->l3_len
+		- pkt->l4_len;
+	if (tcp_dl == 0)
+		return -1;
+
+	ip_id = rte_be_to_cpu_16(ipv4_hdr->packet_id);
+
+	/* find a key and traverse all packets in its item group */
+	key.eth_saddr = eth_hdr->s_addr;
+	key.eth_daddr = eth_hdr->d_addr;
+	key.ip_src_addr = rte_be_to_cpu_32(ipv4_hdr->src_addr);
+	key.ip_dst_addr = rte_be_to_cpu_32(ipv4_hdr->dst_addr);
+	key.src_port = rte_be_to_cpu_16(tcp_hdr->src_port);
+	key.dst_port = rte_be_to_cpu_16(tcp_hdr->dst_port);
+	key.recv_ack = rte_be_to_cpu_32(tcp_hdr->recv_ack);
+
+	for (i = 0; i < tbl->max_key_num; i++) {
+		/* search for a key */
+		if ((tbl->keys[i].is_valid == 0) ||
+				(memcmp(&(tbl->keys[i].key), &key,
+						sizeof(struct tcp4_key)) != 0))
+			continue;
+
+		cur_idx = tbl->keys[i].start_index;
+		prev_idx = cur_idx;
+		while (cur_idx != INVALID_ARRAY_INDEX) {
+			cmp = check_seq_option(tbl->items[cur_idx].pkt,
+					tcp_hdr,
+					ip_id,
+					pkt->l4_len,
+					tcp_dl);
+			if (cmp != 0) {
+				if (merge_two_tcp4_packets(
+							&(tbl->items[cur_idx]),
+							pkt,
+							max_packet_size,
+							cmp) > 0)
+					return 1;
+				/**
+				 * fail to merge two packets since
+				 * it's beyond the max packet length.
+				 * Insert it into the item group.
+				 */
+				item_idx = find_an_empty_item(tbl);
+				if (item_idx == INVALID_ARRAY_INDEX)
+					return -1;
+				tbl->items[prev_idx].next_pkt_idx = item_idx;
+				tbl->items[item_idx].pkt = pkt;
+				tbl->items[item_idx].lastseg =
+					get_mbuf_lastseg(pkt);
+				tbl->items[item_idx].next_pkt_idx =
+					INVALID_ARRAY_INDEX;
+				tbl->items[item_idx].start_time = start_time;
+				tbl->item_num++;
+				return 0;
+			}
+			prev_idx = cur_idx;
+			cur_idx = tbl->items[cur_idx].next_pkt_idx;
+		}
+		/**
+		 * find a corresponding item group but fails to find
+		 * one packet to merge. Insert it into this item group.
+		 */
+		item_idx = find_an_empty_item(tbl);
+		if (item_idx == INVALID_ARRAY_INDEX)
+			return -1;
+		tbl->items[prev_idx].next_pkt_idx = item_idx;
+		tbl->items[item_idx].pkt = pkt;
+		tbl->items[item_idx].lastseg =
+			get_mbuf_lastseg(pkt);
+		tbl->items[item_idx].next_pkt_idx = INVALID_ARRAY_INDEX;
+		tbl->items[item_idx].start_time = start_time;
+		tbl->item_num++;
+		return 0;
+	}
+
+	/**
+	 * merge fail as the given packet has
+	 * a new key. So insert a new key.
+	 */
+	item_idx = find_an_empty_item(tbl);
+	key_idx = find_an_empty_key(tbl);
+	/**
+	 * if current key or item number is greater than the max
+	 * value, don't insert the packet into the table and return
+	 * immediately.
+	 */
+	if (item_idx == INVALID_ARRAY_INDEX ||
+			key_idx == INVALID_ARRAY_INDEX)
+		return -1;
+	tbl->items[item_idx].pkt = pkt;
+	tbl->items[item_idx].lastseg = get_mbuf_lastseg(pkt);
+	tbl->items[item_idx].next_pkt_idx = INVALID_ARRAY_INDEX;
+	tbl->items[item_idx].start_time = start_time;
+	tbl->item_num++;
+
+	memcpy(&(tbl->keys[key_idx].key),
+			&key, sizeof(struct tcp4_key));
+	tbl->keys[key_idx].start_index = item_idx;
+	tbl->keys[key_idx].is_valid = 1;
+	tbl->key_num++;
+
+	return 0;
+}
+
+uint16_t
+gro_tcp4_tbl_timeout_flush(struct gro_tcp4_tbl *tbl,
+		uint64_t timeout_cycles,
+		struct rte_mbuf **out,
+		uint16_t nb_out)
+{
+	uint16_t k = 0;
+	uint32_t i, j;
+	uint64_t current_time;
+
+	current_time = rte_rdtsc();
+	for (i = 0; i < tbl->max_key_num; i++) {
+		/* all keys have been checked, return immediately */
+		if (tbl->key_num == 0)
+			return k;
+
+		if (tbl->keys[i].is_valid == 0)
+			continue;
+
+		j = tbl->keys[i].start_index;
+		while (j != INVALID_ARRAY_INDEX) {
+			if (current_time - tbl->items[j].start_time >=
+					timeout_cycles) {
+				out[k++] = tbl->items[j].pkt;
+				tbl->items[j].pkt = NULL;
+				tbl->item_num--;
+				j = tbl->items[j].next_pkt_idx;
+
+				/**
+				 * delete the key as all of
+				 * its packets are flushed.
+				 */
+				if (j == INVALID_ARRAY_INDEX) {
+					tbl->keys[i].is_valid = 0;
+					tbl->key_num--;
+				} else
+					/* update start_index of the key */
+					tbl->keys[i].start_index = j;
+
+				if (k == nb_out)
+					return k;
+			} else
+				/**
+				 * left packets of this key won't be
+				 * timeout, so go to check other keys.
+				 */
+				break;
+		}
+	}
+	return k;
+}
+
+uint32_t gro_tcp4_tbl_item_num(void *tbl)
+{
+	struct gro_tcp4_tbl *gro_tbl = (struct gro_tcp4_tbl *)tbl;
+
+	if (gro_tbl)
+		return gro_tbl->item_num;
+	return 0;
+}
diff --git a/lib/librte_gro/rte_gro_tcp4.h b/lib/librte_gro/rte_gro_tcp4.h
new file mode 100644
index 0000000..27856f8
--- /dev/null
+++ b/lib/librte_gro/rte_gro_tcp4.h
@@ -0,0 +1,172 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2017 Intel Corporation. All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "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 COPYRIGHT
+ *   OWNER OR CONTRIBUTORS 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.
+ */
+
+#ifndef _RTE_GRO_TCP4_H_
+#define _RTE_GRO_TCP4_H_
+
+#define INVALID_ARRAY_INDEX 0xffffffffUL
+#define GRO_TCP4_TBL_MAX_ITEM_NUM (UINT32_MAX - 1)
+
+/* criteria of mergeing packets */
+struct tcp4_key {
+	struct ether_addr eth_saddr;
+	struct ether_addr eth_daddr;
+	uint32_t ip_src_addr;
+	uint32_t ip_dst_addr;
+
+	uint32_t recv_ack;	/**< acknowledgment sequence number. */
+	uint16_t src_port;
+	uint16_t dst_port;
+};
+
+struct gro_tcp4_key {
+	struct tcp4_key key;
+	uint32_t start_index;	/**< the first packet index of the flow */
+	uint8_t is_valid;
+};
+
+struct gro_tcp4_item {
+	struct rte_mbuf *pkt;	/**< packet address. */
+	struct rte_mbuf *lastseg;	/**< last segment of the packet */
+	/* the time when the packet in added into the table */
+	uint64_t start_time;
+	uint32_t next_pkt_idx;	/**< next packet index. */
+};
+
+/**
+ * TCP/IPv4 reassembly table.
+ */
+struct gro_tcp4_tbl {
+	struct gro_tcp4_item *items;	/**< item array */
+	struct gro_tcp4_key *keys;	/**< key array */
+	uint32_t item_num;	/**< current item number */
+	uint32_t key_num;	/**< current key num */
+	uint32_t max_item_num;	/**< item array size */
+	uint32_t max_key_num;	/**< key array size */
+};
+
+/**
+ * This function creates a TCP/IPv4 reassembly table.
+ *
+ * @param socket_id
+ *  socket index where the Ethernet port connects to.
+ * @param max_flow_num
+ *  the maximum number of flows in the TCP/IPv4 GRO table
+ * @param max_item_per_flow
+ *  the maximum packet number per flow.
+ * @return
+ *  if create successfully, return a pointer which points to the
+ *  created TCP/IPv4 GRO table. Otherwise, return NULL.
+ */
+void *gro_tcp4_tbl_create(uint16_t socket_id,
+		uint16_t max_flow_num,
+		uint16_t max_item_per_flow);
+
+/**
+ * This function destroys a TCP/IPv4 reassembly table.
+ * @param tbl
+ *  a pointer points to the TCP/IPv4 reassembly table.
+ */
+void gro_tcp4_tbl_destroy(void *tbl);
+
+/**
+ * This function searches for a packet in the TCP/IPv4 reassembly table
+ * to merge with the inputted one. To merge two packets is to chain them
+ * together and update packet headers. Packets, whose SYN, FIN, RST, PSH
+ * or URG bit is set, are returned immediately. Packets which only have
+ * packet headers (i.e. without data) are also returned immediately.
+ * Otherwise, the packet is either merged, or inserted into the table.
+ * Besides, if there is no available space to insert the packet, this
+ * function returns immediately too.
+ *
+ * This function assumes the inputted packet is with correct IPv4 and
+ * TCP checksums. And if two packets are merged, it won't re-calculate
+ * IPv4 and TCP checksums. Besides, if the inputted packet is IP
+ * fragmented, it assumes the packet is complete (with TCP header).
+ *
+ * @param pkt
+ *  packet to reassemble.
+ * @param tbl
+ *  a pointer that points to a TCP/IPv4 reassembly table.
+ * @param max_packet_size
+ *  max packet length after merged
+ * @start_time
+ *  the start time that the packet is inserted into the table
+ * @return
+ *  if the packet doesn't have data, or SYN, FIN, RST, PSH or URG bit is
+ *  set, or there is no available space in the table to insert a new
+ *  item or a new key, return a negative value. If the packet is merged
+ *  successfully, return an positive value. If the packet is inserted
+ *  into the table, return 0.
+ */
+int32_t
+gro_tcp4_reassemble(struct rte_mbuf *pkt,
+		struct gro_tcp4_tbl *tbl,
+		uint32_t max_packet_size,
+		uint64_t start_time);
+
+/**
+ * This function flushes timeout packets in a TCP/IPv4 reassembly table
+ * to applications, and without updating checksums for merged packets.
+ * The max number of flushed timeout packets is the element number of
+ * the array which is used to keep flushed packets.
+ *
+ * @param tbl
+ *  a pointer that points to a TCP GRO table.
+ * @param timeout_cycles
+ *  the maximum time that packets can stay in the table.
+ * @param out
+ *  pointer array which is used to keep flushed packets.
+ * @param nb_out
+ *  the element number of out. It's also the max number of timeout
+ *  packets that can be flushed finally.
+ * @return
+ *  the number of packets that are returned.
+ */
+uint16_t
+gro_tcp4_tbl_timeout_flush(struct gro_tcp4_tbl *tbl,
+		uint64_t timeout_cycles,
+		struct rte_mbuf **out,
+		uint16_t nb_out);
+
+/**
+ * This function returns the number of the packets in a TCP/IPv4
+ * reassembly table.
+ *
+ * @param tbl
+ *  pointer points to a TCP/IPv4 reassembly table.
+ * @return
+ *  the number of packets in the table
+ */
+uint32_t
+gro_tcp4_tbl_item_num(void *tbl);
+#endif
