diff --git a/doc/guides/rel_notes/release_17_08.rst b/doc/guides/rel_notes/release_17_08.rst
index a2da17f..1736a3e 100644
--- a/doc/guides/rel_notes/release_17_08.rst
+++ b/doc/guides/rel_notes/release_17_08.rst
@@ -161,6 +161,13 @@ New Features
   to verify functionality and measure the performance parameters of DPDK
   eventdev devices.
 
+* **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..747eeec 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) += gro_tcp4.c
 
 # install this header file
 SYMLINK-$(CONFIG_RTE_LIBRTE_GRO)-include += rte_gro.h
diff --git a/lib/librte_gro/gro_tcp4.c b/lib/librte_gro/gro_tcp4.c
new file mode 100644
index 0000000..61a0423
--- /dev/null
+++ b/lib/librte_gro/gro_tcp4.c
@@ -0,0 +1,505 @@
+/*-
+ *   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 "gro_tcp4.h"
+
+void *
+gro_tcp4_tbl_create(uint16_t socket_id,
+		uint16_t max_flow_num,
+		uint16_t max_item_per_flow)
+{
+	struct gro_tcp4_tbl *tbl;
+	size_t size;
+	uint32_t entries_num, i;
+
+	entries_num = max_flow_num * max_item_per_flow;
+	entries_num = RTE_MIN(entries_num, GRO_TCP4_TBL_MAX_ITEM_NUM);
+
+	if (entries_num == 0)
+		return NULL;
+
+	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 = 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 = rte_zmalloc_socket(__func__,
+			size,
+			RTE_CACHE_LINE_SIZE,
+			socket_id);
+	if (tbl->keys == NULL) {
+		rte_free(tbl->items);
+		rte_free(tbl);
+		return NULL;
+	}
+	/* INVALID_ARRAY_INDEX indicates empty key */
+	for (i = 0; i < entries_num; i++)
+		tbl->keys[i].start_index = INVALID_ARRAY_INDEX;
+	tbl->max_key_num = entries_num;
+
+	return tbl;
+}
+
+void
+gro_tcp4_tbl_destroy(void *tbl)
+{
+	struct gro_tcp4_tbl *tcp_tbl = tbl;
+
+	if (tcp_tbl) {
+		rte_free(tcp_tbl->items);
+		rte_free(tcp_tbl->keys);
+	}
+	rte_free(tcp_tbl);
+}
+
+/*
+ * merge two TCP/IPv4 packets without updating checksums.
+ * If cmp is larger than 0, append the new packet to the
+ * original packet. Otherwise, pre-pend the new packet to
+ * the original packet.
+ */
+static inline int
+merge_two_tcp4_packets(struct gro_tcp4_item *item_src,
+		struct rte_mbuf *pkt,
+		uint16_t ip_id,
+		uint32_t sent_seq,
+		int cmp)
+{
+	struct rte_mbuf *pkt_head, *pkt_tail, *lastseg;
+	uint16_t tcp_datalen;
+
+	if (cmp > 0) {
+		pkt_head = item_src->firstseg;
+		pkt_tail = pkt;
+	} else {
+		pkt_head = pkt;
+		pkt_tail = item_src->firstseg;
+	}
+
+	/* check if the packet length will be beyond the max value */
+	tcp_datalen = pkt_tail->pkt_len - pkt_tail->l2_len -
+		pkt_tail->l3_len - pkt_tail->l4_len;
+	if (pkt_head->pkt_len - pkt_head->l2_len + tcp_datalen >
+			TCP4_MAX_L3_LENGTH)
+		return 0;
+
+	/* remove packet header for the tail packet */
+	rte_pktmbuf_adj(pkt_tail,
+			pkt_tail->l2_len +
+			pkt_tail->l3_len +
+			pkt_tail->l4_len);
+
+	/* chain two packets together */
+	if (cmp > 0) {
+		item_src->lastseg->next = pkt;
+		item_src->lastseg = rte_pktmbuf_lastseg(pkt);
+		/* update IP ID to the larger value */
+		item_src->ip_id = ip_id;
+	} else {
+		lastseg = rte_pktmbuf_lastseg(pkt);
+		lastseg->next = item_src->firstseg;
+		item_src->firstseg = pkt;
+		/* update sent_seq to the smaller value */
+		item_src->sent_seq = sent_seq;
+	}
+	item_src->nb_merged++;
+
+	/* 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 inline int
+check_seq_option(struct gro_tcp4_item *item,
+		struct tcp_hdr *tcp_hdr,
+		uint16_t tcp_hl,
+		uint16_t tcp_dl,
+		uint16_t ip_id,
+		uint32_t sent_seq)
+{
+	struct rte_mbuf *pkt0 = item->firstseg;
+	struct ipv4_hdr *ipv4_hdr0;
+	struct tcp_hdr *tcp_hdr0;
+	uint16_t tcp_hl0, tcp_dl0;
+	uint16_t len;
+
+	ipv4_hdr0 = (struct ipv4_hdr *)(rte_pktmbuf_mtod(pkt0, char *) +
+			pkt0->l2_len);
+	tcp_hdr0 = (struct tcp_hdr *)((char *)ipv4_hdr0 + pkt0->l3_len);
+	tcp_hl0 = pkt0->l4_len;
+
+	/* 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 */
+	tcp_dl0 = pkt0->pkt_len - pkt0->l2_len - pkt0->l3_len - tcp_hl0;
+	if ((sent_seq == (item->sent_seq + tcp_dl0)) &&
+			(ip_id == (item->ip_id + 1)))
+		/* append the new packet */
+		return 1;
+	else if (((sent_seq + tcp_dl) == item->sent_seq) &&
+			((ip_id + item->nb_merged) == item->ip_id))
+		/* pre-pend the new packet */
+		return -1;
+	else
+		return 0;
+}
+
+static inline uint32_t
+find_an_empty_item(struct gro_tcp4_tbl *tbl)
+{
+	uint32_t i;
+	uint32_t max_item_num = tbl->max_item_num;
+
+	for (i = 0; i < max_item_num; i++)
+		if (tbl->items[i].firstseg == NULL)
+			return i;
+	return INVALID_ARRAY_INDEX;
+}
+
+static inline uint32_t
+find_an_empty_key(struct gro_tcp4_tbl *tbl)
+{
+	uint32_t i;
+	uint32_t max_key_num = tbl->max_key_num;
+
+	for (i = 0; i < max_key_num; i++)
+		if (tbl->keys[i].start_index == INVALID_ARRAY_INDEX)
+			return i;
+	return INVALID_ARRAY_INDEX;
+}
+
+static inline uint32_t
+insert_new_item(struct gro_tcp4_tbl *tbl,
+		struct rte_mbuf *pkt,
+		uint16_t ip_id,
+		uint32_t sent_seq,
+		uint32_t prev_idx,
+		uint64_t start_time)
+{
+	uint32_t item_idx;
+
+	item_idx = find_an_empty_item(tbl);
+	if (item_idx == INVALID_ARRAY_INDEX)
+		return INVALID_ARRAY_INDEX;
+
+	tbl->items[item_idx].firstseg = pkt;
+	tbl->items[item_idx].lastseg = rte_pktmbuf_lastseg(pkt);
+	tbl->items[item_idx].start_time = start_time;
+	tbl->items[item_idx].next_pkt_idx = INVALID_ARRAY_INDEX;
+	tbl->items[item_idx].sent_seq = sent_seq;
+	tbl->items[item_idx].ip_id = ip_id;
+	tbl->items[item_idx].nb_merged = 1;
+	tbl->item_num++;
+
+	/* if the previous packet exists, chain the new one with it */
+	if (prev_idx != INVALID_ARRAY_INDEX) {
+		tbl->items[item_idx].next_pkt_idx =
+			tbl->items[prev_idx].next_pkt_idx;
+		tbl->items[prev_idx].next_pkt_idx = item_idx;
+	}
+
+	return item_idx;
+}
+
+static inline uint32_t
+delete_item(struct gro_tcp4_tbl *tbl, uint32_t item_idx,
+		uint32_t prev_item_idx)
+{
+	uint32_t next_idx = tbl->items[item_idx].next_pkt_idx;
+
+	/* set NULL to firstseg to indicate it's an empty item */
+	tbl->items[item_idx].firstseg = NULL;
+	tbl->item_num--;
+	if (prev_item_idx != INVALID_ARRAY_INDEX)
+		tbl->items[prev_item_idx].next_pkt_idx = next_idx;
+
+	return next_idx;
+}
+
+static inline uint32_t
+insert_new_key(struct gro_tcp4_tbl *tbl,
+		struct tcp4_key *key_src,
+		uint32_t item_idx)
+{
+	struct tcp4_key *key_dst;
+	uint32_t key_idx;
+
+	key_idx = find_an_empty_key(tbl);
+	if (key_idx == INVALID_ARRAY_INDEX)
+		return INVALID_ARRAY_INDEX;
+
+	key_dst = &(tbl->keys[key_idx].key);
+
+	ether_addr_copy(&(key_src->eth_saddr), &(key_dst->eth_saddr));
+	ether_addr_copy(&(key_src->eth_daddr), &(key_dst->eth_daddr));
+	key_dst->ip_src_addr = key_src->ip_src_addr;
+	key_dst->ip_dst_addr = key_src->ip_dst_addr;
+	key_dst->recv_ack = key_src->recv_ack;
+	key_dst->src_port = key_src->src_port;
+	key_dst->dst_port = key_src->dst_port;
+
+	/* non-INVALID_ARRAY_INDEX value indicates this key is valid */
+	tbl->keys[key_idx].start_index = item_idx;
+	tbl->key_num++;
+
+	return key_idx;
+}
+
+static inline int
+is_same_key(struct tcp4_key k1, struct tcp4_key k2)
+{
+	if (is_same_ether_addr(&k1.eth_saddr, &k2.eth_saddr) == 0)
+		return 0;
+
+	if (is_same_ether_addr(&k1.eth_daddr, &k2.eth_daddr) == 0)
+		return 0;
+
+	return ((k1.ip_src_addr == k2.ip_src_addr) &&
+			(k1.ip_dst_addr == k2.ip_dst_addr) &&
+			(k1.recv_ack == k2.recv_ack) &&
+			(k1.src_port == k2.src_port) &&
+			(k1.dst_port == k2.dst_port));
+}
+
+/*
+ * update packet length for the flushed packet.
+ */
+static inline void
+update_header(struct gro_tcp4_item *item)
+{
+	struct ipv4_hdr *ipv4_hdr;
+	struct rte_mbuf *pkt = item->firstseg;
+
+	ipv4_hdr = (struct ipv4_hdr *)(rte_pktmbuf_mtod(pkt, char *) +
+			pkt->l2_len);
+	ipv4_hdr->total_length = rte_cpu_to_be_16(pkt->pkt_len -
+			pkt->l2_len);
+}
+
+int32_t
+gro_tcp4_reassemble(struct rte_mbuf *pkt,
+		struct gro_tcp4_tbl *tbl,
+		uint64_t start_time)
+{
+	struct ether_hdr *eth_hdr;
+	struct ipv4_hdr *ipv4_hdr;
+	struct tcp_hdr *tcp_hdr;
+	uint32_t sent_seq;
+	uint16_t tcp_dl, ip_id;
+
+	struct tcp4_key key;
+	uint32_t cur_idx, prev_idx, item_idx;
+	uint32_t i, max_key_num;
+	int cmp;
+
+	eth_hdr = rte_pktmbuf_mtod(pkt, struct ether_hdr *);
+	ipv4_hdr = (struct ipv4_hdr *)((char *)eth_hdr + pkt->l2_len);
+	tcp_hdr = (struct tcp_hdr *)((char *)ipv4_hdr + pkt->l3_len);
+
+	/*
+	 * if FIN, SYN, RST, PSH, URG, ECE or
+	 * CWR is set, return immediately.
+	 */
+	if (tcp_hdr->tcp_flags != TCP_ACK_FLAG)
+		return -1;
+	/* if payload length is 0, return immediately */
+	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);
+	sent_seq = rte_be_to_cpu_32(tcp_hdr->sent_seq);
+
+	ether_addr_copy(&(eth_hdr->s_addr), &(key.eth_saddr));
+	ether_addr_copy(&(eth_hdr->d_addr), &(key.eth_daddr));
+	key.ip_src_addr = ipv4_hdr->src_addr;
+	key.ip_dst_addr = ipv4_hdr->dst_addr;
+	key.src_port = tcp_hdr->src_port;
+	key.dst_port = tcp_hdr->dst_port;
+	key.recv_ack = tcp_hdr->recv_ack;
+
+	/* search for a key */
+	max_key_num = tbl->max_key_num;
+	for (i = 0; i < max_key_num; i++) {
+		if ((tbl->keys[i].start_index != INVALID_ARRAY_INDEX) &&
+				is_same_key(tbl->keys[i].key, key))
+			break;
+	}
+
+	/* can't find a key, so insert a new key and a new item. */
+	if (i == tbl->max_key_num) {
+		item_idx = insert_new_item(tbl, pkt, ip_id, sent_seq,
+				INVALID_ARRAY_INDEX, start_time);
+		if (item_idx == INVALID_ARRAY_INDEX)
+			return -1;
+		if (insert_new_key(tbl, &key, item_idx) ==
+				INVALID_ARRAY_INDEX) {
+			/*
+			 * fail to insert a new key, so
+			 * delete the inserted item
+			 */
+			delete_item(tbl, item_idx, INVALID_ARRAY_INDEX);
+			return -1;
+		}
+		return 0;
+	}
+
+	/* traverse all packets in the item group to find one to merge */
+	cur_idx = tbl->keys[i].start_index;
+	prev_idx = cur_idx;
+	do {
+		cmp = check_seq_option(&(tbl->items[cur_idx]), tcp_hdr,
+				pkt->l4_len, tcp_dl, ip_id, sent_seq);
+		if (cmp) {
+			if (merge_two_tcp4_packets(&(tbl->items[cur_idx]),
+						pkt, ip_id,
+						sent_seq, cmp))
+				return 1;
+			/*
+			 * fail to merge two packets since the packet
+			 * length will be greater than the max value.
+			 * So insert the packet into the item group.
+			 */
+			if (insert_new_item(tbl, pkt, ip_id, sent_seq,
+						prev_idx, start_time) ==
+					INVALID_ARRAY_INDEX)
+				return -1;
+			return 0;
+		}
+		prev_idx = cur_idx;
+		cur_idx = tbl->items[cur_idx].next_pkt_idx;
+	} while (cur_idx != INVALID_ARRAY_INDEX);
+
+	/*
+	 * can't find a packet in the item group to merge,
+	 * so insert the packet into the item group.
+	 */
+	if (insert_new_item(tbl, pkt, ip_id, sent_seq, prev_idx,
+				start_time) == INVALID_ARRAY_INDEX)
+		return -1;
+
+	return 0;
+}
+
+uint16_t
+gro_tcp4_tbl_timeout_flush(struct gro_tcp4_tbl *tbl,
+		uint64_t flush_timestamp,
+		struct rte_mbuf **out,
+		uint16_t nb_out)
+{
+	uint16_t k = 0;
+	uint32_t i, j;
+	uint32_t max_key_num = tbl->max_key_num;
+
+	for (i = 0; i < max_key_num; i++) {
+		/* all keys have been checked, return immediately */
+		if (tbl->key_num == 0)
+			return k;
+
+		j = tbl->keys[i].start_index;
+		while (j != INVALID_ARRAY_INDEX) {
+			if (tbl->items[j].start_time <= flush_timestamp) {
+				out[k++] = tbl->items[j].firstseg;
+				if (tbl->items[j].nb_merged > 1)
+					update_header(&(tbl->items[j]));
+				/*
+				 * delete the item and get
+				 * the next packet index
+				 */
+				j = delete_item(tbl, j,
+						INVALID_ARRAY_INDEX);
+
+				/*
+				 * delete the key as all of
+				 * packets are flushed
+				 */
+				if (j == INVALID_ARRAY_INDEX) {
+					tbl->keys[i].start_index =
+						INVALID_ARRAY_INDEX;
+					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_pkt_count(void *tbl)
+{
+	struct gro_tcp4_tbl *gro_tbl = tbl;
+
+	if (gro_tbl)
+		return gro_tbl->item_num;
+
+	return 0;
+}
diff --git a/lib/librte_gro/gro_tcp4.h b/lib/librte_gro/gro_tcp4.h
new file mode 100644
index 0000000..f41dcee
--- /dev/null
+++ b/lib/librte_gro/gro_tcp4.h
@@ -0,0 +1,210 @@
+/*-
+ *   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 _GRO_TCP4_H_
+#define _GRO_TCP4_H_
+
+#define INVALID_ARRAY_INDEX 0xffffffffUL
+#define GRO_TCP4_TBL_MAX_ITEM_NUM (1024UL * 1024UL)
+
+/*
+ * the max L3 length of a TCP/IPv4 packet. The L3 length
+ * is the sum of ipv4 header, tcp header and L4 payload.
+ */
+#define TCP4_MAX_L3_LENGTH UINT16_MAX
+
+/* 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;
+	uint16_t src_port;
+	uint16_t dst_port;
+};
+
+struct gro_tcp4_key {
+	struct tcp4_key key;
+	/*
+	 * the index of the first packet in the item group.
+	 * If the value is INVALID_ARRAY_INDEX, it means
+	 * the key is empty.
+	 */
+	uint32_t start_index;
+};
+
+struct gro_tcp4_item {
+	/*
+	 * first segment of the packet. If the value
+	 * is NULL, it means the item is empty.
+	 */
+	struct rte_mbuf *firstseg;
+	/* last segment of the packet */
+	struct rte_mbuf *lastseg;
+	/*
+	 * the time when the first packet is inserted
+	 * into the table. If a packet in the table is
+	 * merged with an incoming packet, this value
+	 * won't be updated. We set this value only
+	 * when the first packet is inserted into the
+	 * table.
+	 */
+	uint64_t start_time;
+	/*
+	 * we use next_pkt_idx to chain the packets that
+	 * have same key value but can't be merged together.
+	 */
+	uint32_t next_pkt_idx;
+	/* the sequence number of the packet */
+	uint32_t sent_seq;
+	/* the IP ID of the packet */
+	uint16_t ip_id;
+	/* the number of merged packets */
+	uint16_t nb_merged;
+};
+
+/*
+ * TCP/IPv4 reassembly table structure.
+ */
+struct gro_tcp4_tbl {
+	/* item array */
+	struct gro_tcp4_item *items;
+	/* key array */
+	struct gro_tcp4_key *keys;
+	/* current item number */
+	uint32_t item_num;
+	/* current key num */
+	uint32_t key_num;
+	/* item array size */
+	uint32_t max_item_num;
+	/* key array size */
+	uint32_t max_key_num;
+};
+
+/**
+ * This function creates a TCP/IPv4 reassembly table.
+ *
+ * @param socket_id
+ *  socket index for allocating TCP/IPv4 reassemblt table
+ * @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
+ * CWR, ECE 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.
+ * @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, CWR, ECE
+ *  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,
+		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 flush_timestamp
+ *  this function flushes packets which are inserted into the table
+ *  before or at the flush_timestamp.
+ * @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 flush_timestamp,
+		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_pkt_count(void *tbl);
+#endif
diff --git a/lib/librte_gro/rte_gro.c b/lib/librte_gro/rte_gro.c
index fa6d7ce..4624485 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 "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_pkt_count_fn)(void *tbl);
 
-static gro_tbl_create_fn tbl_create_fn[RTE_GRO_TYPE_MAX_NUM];
-static gro_tbl_destroy_fn tbl_destroy_fn[RTE_GRO_TYPE_MAX_NUM];
-static gro_tbl_pkt_count_fn tbl_pkt_count_fn[RTE_GRO_TYPE_MAX_NUM];
+static gro_tbl_create_fn tbl_create_fn[RTE_GRO_TYPE_MAX_NUM] = {
+		gro_tcp4_tbl_create, NULL};
+static gro_tbl_destroy_fn tbl_destroy_fn[RTE_GRO_TYPE_MAX_NUM] = {
+			gro_tcp4_tbl_destroy, NULL};
+static gro_tbl_pkt_count_fn tbl_pkt_count_fn[RTE_GRO_TYPE_MAX_NUM] = {
+			gro_tcp4_tbl_pkt_count, NULL};
 
 /*
  * GRO context structure, which is used to merge packets. It keeps
@@ -121,28 +127,131 @@ rte_gro_ctx_destroy(void *ctx)
 }
 
 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];
+	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->gro_types & RTE_GRO_TCP_IPV4) == 0)
+		return nb_pkts;
+
+	/* get the actual number of packets */
+	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);
+
+	for (i = 0; i < item_num; i++)
+		tcp_keys[i].start_index = INVALID_ARRAY_INDEX;
+
+	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 ((pkts[i]->packet_type & (RTE_PTYPE_L3_IPV4 |
+					RTE_PTYPE_L4_TCP)) ==
+				(RTE_PTYPE_L3_IPV4 | RTE_PTYPE_L4_TCP)) {
+			ret = gro_tcp4_reassemble(pkts[i],
+					&tcp_tbl,
+					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, current_time,
+				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 *ctx __rte_unused)
+		void *ctx)
 {
-	return nb_pkts;
+	uint16_t i, unprocess_num = 0;
+	struct rte_mbuf *unprocess_pkts[nb_pkts];
+	struct gro_ctx *gro_ctx = ctx;
+	uint64_t current_time;
+
+	if ((gro_ctx->gro_types & RTE_GRO_TCP_IPV4) == 0)
+		return nb_pkts;
+
+	current_time = rte_rdtsc();
+
+	for (i = 0; i < nb_pkts; i++) {
+		if ((pkts[i]->packet_type & (RTE_PTYPE_L3_IPV4 |
+					RTE_PTYPE_L4_TCP)) ==
+				(RTE_PTYPE_L3_IPV4 | RTE_PTYPE_L4_TCP)) {
+			if (gro_tcp4_reassemble(pkts[i],
+						gro_ctx->tbls
+						[RTE_GRO_TCP_IPV4_INDEX],
+						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 *ctx __rte_unused,
-		uint64_t timeout_cycles __rte_unused,
-		uint64_t gro_types __rte_unused,
-		struct rte_mbuf **out __rte_unused,
-		uint16_t max_nb_out __rte_unused)
+rte_gro_timeout_flush(void *ctx,
+		uint64_t timeout_cycles,
+		uint64_t gro_types,
+		struct rte_mbuf **out,
+		uint16_t max_nb_out)
 {
+	struct gro_ctx *gro_ctx = ctx;
+	uint64_t flush_timestamp;
+
+	gro_types = gro_types & gro_ctx->gro_types;
+	flush_timestamp = rte_rdtsc() - timeout_cycles;
+
+	if (gro_types & RTE_GRO_TCP_IPV4) {
+		return gro_tcp4_tbl_timeout_flush(
+				gro_ctx->tbls[RTE_GRO_TCP_IPV4_INDEX],
+				flush_timestamp,
+				out, max_nb_out);
+	}
 	return 0;
 }
 
diff --git a/lib/librte_gro/rte_gro.h b/lib/librte_gro/rte_gro.h
index 53ddd15..3b4fec0 100644
--- a/lib/librte_gro/rte_gro.h
+++ b/lib/librte_gro/rte_gro.h
@@ -45,8 +45,11 @@ extern "C" {
 /**< max number of supported GRO types */
 #define RTE_GRO_TYPE_MAX_NUM 64
 /**< current supported GRO num */
-#define RTE_GRO_TYPE_SUPPORT_NUM 0
+#define RTE_GRO_TYPE_SUPPORT_NUM 1
 
+/**< 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 {
 	/**< desired GRO types */
