diff mbox

[2/2] batman-adv: layer2 unicast packet fragmentation

Message ID 1278366265-2626-2-git-send-email-an.langer@gmx.de
State Superseded, archived
Headers show

Commit Message

Andreas Langer July 5, 2010, 9:44 p.m. UTC
This patch implements a simple layer2 fragmentation to allow traffic exchange over
network interfaces with a MTU smaller than 1500 bytes. The fragmentation splits the
big packets into two parts and marks the frames accordingly. The receiving end
buffers the packets to reassemble the orignal packet before passing it to the higher
layers. This feature makes it necessary to modify the batman-adv encapsulation for
unicast packets by adding a sequence number, flags and the originator address.
This modifcation is part of a seperate packet type for fragemented packets to keep
the original overhead as low as possible. This patch enables the feature by default
to ensure the data traffic can travel through the network. But it also prints a
warning to notify the user about the performance implications.

Note: Fragmentation should be avoided at all costs since it has a dramatic impact on
the performance, especially when it comes wifi networks. Instead of a single packet,
2 packets have to be sent! Not only valuable airtime is wasted but also packetloss
decreases the throughput. A link with 50% packetloss and fragmentation enabled is
pretty much unusable.

Signed-off-by: Andreas Langer <an.langer at gmx.de>
---
 batman-adv/Makefile.kbuild  |    2 +-
 batman-adv/bat_sysfs.c      |   55 ++++++++++++++++
 batman-adv/fragmentation.c  |  152 +++++++++++++++++++++++++++++++++++++++++++
 batman-adv/fragmentation.h  |   34 ++++++++++
 batman-adv/hard-interface.c |   34 +++++++++-
 batman-adv/originator.c     |   10 +++
 batman-adv/packet.h         |   26 ++++++--
 batman-adv/routing.c        |  144 ++++++++++++++++++++++++++++++++---------
 batman-adv/routing.h        |    1 +
 batman-adv/soft-interface.c |   76 ++++++++++++++++++----
 batman-adv/types.h          |   10 +++
 11 files changed, 493 insertions(+), 51 deletions(-)
 create mode 100644 batman-adv/fragmentation.c
 create mode 100644 batman-adv/fragmentation.h
diff mbox

Patch

diff --git a/batman-adv/Makefile.kbuild b/batman-adv/Makefile.kbuild
index 762ee4e..3e99ba5 100644
--- a/batman-adv/Makefile.kbuild
+++ b/batman-adv/Makefile.kbuild
@@ -32,4 +32,4 @@  EXTRA_CFLAGS += -DREVISION_VERSION=\"$(REVISION)\"
 endif
 
 obj-m += batman-adv.o
-batman-adv-objs := main.o bat_debugfs.o bat_sysfs.o send.o routing.o soft-interface.o icmp_socket.o translation-table.o bitarray.o hash.o ring_buffer.o vis.o hard-interface.o aggregation.o originator.o gateway_common.o gateway_client.o $(shell [ "2" -eq "$(VERSION)" ] 2>&- && [ "6" -eq "$(PATCHLEVEL)" ] 2>&- && [ "$(SUBLEVEL)" -le "28" ] 2>&- && echo bat_printk.o)
+batman-adv-objs := main.o bat_debugfs.o bat_sysfs.o send.o routing.o soft-interface.o icmp_socket.o translation-table.o bitarray.o hash.o ring_buffer.o vis.o hard-interface.o aggregation.o originator.o gateway_common.o gateway_client.o fragmentation.o $(shell [ "2" -eq "$(VERSION)" ] 2>&- && [ "6" -eq "$(PATCHLEVEL)" ] 2>&- && [ "$(SUBLEVEL)" -le "28" ] 2>&- && echo bat_printk.o)
diff --git a/batman-adv/bat_sysfs.c b/batman-adv/bat_sysfs.c
index b5d47ca..04db890 100644
--- a/batman-adv/bat_sysfs.c
+++ b/batman-adv/bat_sysfs.c
@@ -137,6 +137,58 @@  static ssize_t store_bond(struct kobject *kobj, struct attribute *attr,
 	return count;
 }
 
+static ssize_t show_frag(struct kobject *kobj, struct attribute *attr,
+			     char *buff)
+{
+	struct device *dev = to_dev(kobj->parent);
+	struct bat_priv *bat_priv = netdev_priv(to_net_dev(dev));
+	int frag_status = atomic_read(&bat_priv->frag_enabled);
+
+	return sprintf(buff, "%s\n",
+		       frag_status == 0 ? "disabled" : "enabled");
+}
+
+static ssize_t store_frag(struct kobject *kobj, struct attribute *attr,
+			  char *buff, size_t count)
+{
+	struct device *dev = to_dev(kobj->parent);
+	struct net_device *net_dev = to_net_dev(dev);
+	struct bat_priv *bat_priv = netdev_priv(net_dev);
+	int frag_enabled_tmp = -1;
+
+	if (((count == 2) && (buff[0] == '1')) ||
+	    (strncmp(buff, "enable", 6) == 0))
+		frag_enabled_tmp = 1;
+
+	if (((count == 2) && (buff[0] == '0')) ||
+	    (strncmp(buff, "disable", 7) == 0))
+		frag_enabled_tmp = 0;
+
+	if (frag_enabled_tmp < 0) {
+		if (buff[count - 1] == '\n')
+			buff[count - 1] = '\0';
+
+		bat_err(net_dev,
+			"Invalid parameter for 'fragmentation' setting on mesh"
+			"received: %s\n", buff);
+		return -EINVAL;
+	}
+
+	if (atomic_read(&bat_priv->frag_enabled) == frag_enabled_tmp)
+		return count;
+
+	bat_info(net_dev, "Changing fragmentation from: %s to: %s\n",
+		 atomic_read(&bat_priv->frag_enabled) == 1 ?
+		 "enabled" : "disabled",
+		 frag_enabled_tmp == 1 ? "enabled" : "disabled");
+
+	atomic_set(&bat_priv->frag_enabled, (unsigned)frag_enabled_tmp);
+
+	update_min_mtu();
+
+	return count;
+}
+
 static ssize_t show_vis_mode(struct kobject *kobj, struct attribute *attr,
 			     char *buff)
 {
@@ -325,6 +377,7 @@  static ssize_t store_log_level(struct kobject *kobj, struct attribute *attr,
 static BAT_ATTR(aggregated_ogms, S_IRUGO | S_IWUSR,
 		show_aggr_ogms, store_aggr_ogms);
 static BAT_ATTR(bonding, S_IRUGO | S_IWUSR, show_bond, store_bond);
+static BAT_ATTR(fragmentation, S_IRUGO | S_IWUSR, show_frag, store_frag);
 static BAT_ATTR(vis_mode, S_IRUGO | S_IWUSR, show_vis_mode, store_vis_mode);
 static BAT_ATTR(gw_mode, S_IRUGO | S_IWUSR, show_gw_mode, store_gw_mode);
 static BAT_ATTR(orig_interval, S_IRUGO | S_IWUSR,
@@ -336,6 +389,7 @@  static BAT_ATTR(log_level, S_IRUGO | S_IWUSR, show_log_level, store_log_level);
 static struct bat_attribute *mesh_attrs[] = {
 	&bat_attr_aggregated_ogms,
 	&bat_attr_bonding,
+	&bat_attr_fragmentation,
 	&bat_attr_vis_mode,
 	&bat_attr_gw_mode,
 	&bat_attr_orig_interval,
@@ -356,6 +410,7 @@  int sysfs_add_meshif(struct net_device *dev)
 		  routine as soon as we have it */
 	atomic_set(&bat_priv->aggregation_enabled, 1);
 	atomic_set(&bat_priv->bonding_enabled, 0);
+	atomic_set(&bat_priv->frag_enabled, 1);
 	atomic_set(&bat_priv->vis_mode, VIS_TYPE_CLIENT_UPDATE);
 	atomic_set(&bat_priv->gw_mode, GW_MODE_OFF);
 	atomic_set(&bat_priv->gw_class, 0);
diff --git a/batman-adv/fragmentation.c b/batman-adv/fragmentation.c
new file mode 100644
index 0000000..77fd355
--- /dev/null
+++ b/batman-adv/fragmentation.c
@@ -0,0 +1,152 @@ 
+/*
+ * Copyright (C) 2010 B.A.T.M.A.N. contributors:
+ *
+ * Andreas Langer
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA
+ *
+ */
+#include "main.h"
+#include "fragmentation.h"
+
+
+struct sk_buff *merge_frag_packet(struct list_head *head,
+	struct frag_packet_list_entry *tfp,
+	struct sk_buff *skb) {
+
+	struct unicast_frag_packet *up =
+		(struct unicast_frag_packet *) skb->data;
+	struct sk_buff *tmp_skb;
+
+	/* set skb to the first part and tmp_skb to the second part */
+	if (up->flags & UNI_FRAG_HEAD) {
+		tmp_skb = tfp->skb;
+	} else {
+		tmp_skb = skb;
+		skb = tfp->skb;
+	}
+
+	skb_pull(tmp_skb, sizeof(struct unicast_frag_packet));
+	if (pskb_expand_head(skb, 0, tmp_skb->len, GFP_ATOMIC) < 0) {
+		/* free buffered skb, skb will be freed later */
+		kfree_skb(tfp->skb);
+		return NULL;
+	}
+
+	/* move free entry to end */
+	tfp->skb = NULL;
+	tfp->seqno = 0;
+	list_move_tail(&tfp->list, head);
+
+	memcpy(skb_put(skb, tmp_skb->len), tmp_skb->data, tmp_skb->len);
+	kfree_skb(tmp_skb);
+	return skb;
+}
+
+void create_frag_entry(struct list_head *head, struct sk_buff *skb)
+{
+	struct frag_packet_list_entry *tfp;
+	struct unicast_frag_packet *up =
+		(struct unicast_frag_packet *) skb->data;
+
+	/* free and oldest packets stand at the end */
+	tfp = list_entry((head)->prev, typeof(*tfp), list);
+
+	if (tfp->skb)
+		kfree_skb(tfp->skb);
+
+	tfp->seqno = ntohs(up->seqno);
+	tfp->skb = skb;
+	list_move(&tfp->list, head);
+	return;
+}
+
+void create_frag_buffer(struct list_head *head)
+{
+	int i;
+	struct frag_packet_list_entry *tfp;
+
+	for (i = 0; i < FRAG_BUFFER_SIZE; i++) {
+		tfp = kmalloc(sizeof(struct frag_packet_list_entry),
+			GFP_ATOMIC);
+		tfp->skb = NULL;
+		tfp->seqno = 0;
+		INIT_LIST_HEAD(&tfp->list);
+		list_add(&tfp->list, head);
+	}
+
+	return;
+}
+
+struct frag_packet_list_entry *search_frag_packet(struct list_head *head,
+	struct unicast_frag_packet *up) {
+
+	struct frag_packet_list_entry *tfp;
+	struct unicast_frag_packet *tmp_up = NULL;
+
+	list_for_each_entry(tfp, head, list) {
+
+		if (!tfp->skb)
+			continue;
+
+		if (tfp->seqno == ntohs(up->seqno))
+			goto mov_tail;
+
+		tmp_up = (struct unicast_frag_packet *) tfp->skb->data;
+
+		if (up->flags & UNI_FRAG_HEAD) {
+
+			if (tfp->seqno == ntohs(up->seqno)+1) {
+				if (tmp_up->flags & UNI_FRAG_HEAD)
+					goto mov_tail;
+				else
+					goto ret_tfp;
+			}
+		} else {
+
+			if (tfp->seqno == ntohs(up->seqno)-1) {
+				if (tmp_up->flags & UNI_FRAG_HEAD)
+					goto ret_tfp;
+				else
+					goto mov_tail;
+			}
+		}
+	}
+	goto ret_null;
+
+ret_tfp:
+	return tfp;
+mov_tail:
+	list_move_tail(&tfp->list, head);
+ret_null:
+	return NULL;
+}
+
+void frag_list_free(struct list_head *head)
+{
+
+	struct frag_packet_list_entry *pf, *tmp_pf;
+
+	if (!list_empty(head)) {
+
+		list_for_each_entry_safe(pf, tmp_pf, head, list) {
+			if (pf->skb)
+				kfree_skb(pf->skb);
+			list_del(&pf->list);
+			kfree(pf);
+		}
+	}
+	return;
+}
diff --git a/batman-adv/fragmentation.h b/batman-adv/fragmentation.h
new file mode 100644
index 0000000..09011b3
--- /dev/null
+++ b/batman-adv/fragmentation.h
@@ -0,0 +1,34 @@ 
+/*
+ * Copyright (C) 2010 B.A.T.M.A.N. contributors:
+ *
+ * Andreas Langer
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA
+ *
+ */
+
+#define FRAG_TIMEOUT 60000	/* purge frag list entrys after time in ms */
+#define FRAG_BUFFER_SIZE 6	/* number of list elements in buffer */
+#define FRAG_MAX_SEQ 65535
+
+struct sk_buff *merge_frag_packet(struct list_head *head,
+	struct frag_packet_list_entry *tfp,
+	struct sk_buff *skb);
+
+void create_frag_entry(struct list_head *head, struct sk_buff *skb);
+void create_frag_buffer(struct list_head *head);
+struct frag_packet_list_entry *search_frag_packet(struct list_head *head,
+	struct unicast_frag_packet *up);
+void frag_list_free(struct list_head *head);
diff --git a/batman-adv/hard-interface.c b/batman-adv/hard-interface.c
index 5ff9dcb..87c84c1 100644
--- a/batman-adv/hard-interface.c
+++ b/batman-adv/hard-interface.c
@@ -166,6 +166,11 @@  int hardif_min_mtu(void)
 	/* allow big frames if all devices are capable to do so
 	 * (have MTU > 1500 + BAT_HEADER_LEN) */
 	int min_mtu = ETH_DATA_LEN;
+	/* FIXME: each batman_if will be attached to a softif */
+	struct bat_priv *bat_priv = netdev_priv(soft_device);
+
+	if (atomic_read(&bat_priv->frag_enabled))
+		goto out;
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(batman_if, &if_list, list) {
@@ -175,7 +180,7 @@  int hardif_min_mtu(void)
 				      min_mtu);
 	}
 	rcu_read_unlock();
-
+out:
 	return min_mtu;
 }
 
@@ -265,8 +270,30 @@  int hardif_enable_interface(struct batman_if *batman_if)
 	orig_hash_add_if(batman_if, bat_priv->num_ifaces);
 
 	atomic_set(&batman_if->seqno, 1);
+	atomic_set(&batman_if->frag_seqno, 1);
 	bat_info(soft_device, "Adding interface: %s\n", batman_if->dev);
 
+	if (atomic_read(&bat_priv->frag_enabled) && batman_if->net_dev->mtu <
+		ETH_DATA_LEN + BAT_HEADER_LEN)
+		bat_info(soft_device,
+			"The MTU of interface %s is too small (%zi) to handle "
+			"the transport of batman-adv packets. Packets going "
+			"over this interface will be fragmented on layer2 "
+			"which could impact the performance. Setting the MTU "
+			"to %zi would solve the problem.\n",
+			batman_if->dev, ETH_DATA_LEN + BAT_HEADER_LEN,
+			ETH_DATA_LEN + BAT_HEADER_LEN);
+
+	if (!atomic_read(&bat_priv->frag_enabled) && batman_if->net_dev->mtu <
+		ETH_DATA_LEN + BAT_HEADER_LEN)
+		bat_info(soft_device,
+			"The MTU of interface %s is too small (%zi) to handle "
+			"the transport of batman-adv packets. If you experience"
+			" problems getting traffic through try increasing the "
+			"MTU to %zi.\n",
+			batman_if->dev, ETH_DATA_LEN + BAT_HEADER_LEN,
+			ETH_DATA_LEN + BAT_HEADER_LEN);
+
 	if (hardif_is_iface_up(batman_if))
 		hardif_activate_interface(soft_device, bat_priv, batman_if);
 	else
@@ -514,6 +541,11 @@  int batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
 		ret = recv_unicast_packet(skb, batman_if);
 		break;
 
+		/* fragmented unicast packet */
+	case BAT_UNICAST_FRAG:
+		ret = recv_ucast_frag_packet(skb, batman_if);
+		break;
+
 		/* broadcast packet */
 	case BAT_BCAST:
 		ret = recv_bcast_packet(skb);
diff --git a/batman-adv/originator.c b/batman-adv/originator.c
index 5343ab2..66852ea 100644
--- a/batman-adv/originator.c
+++ b/batman-adv/originator.c
@@ -29,6 +29,7 @@ 
 #include "compat.h"
 #include "gateway_client.h"
 #include "hard-interface.h"
+#include "fragmentation.h"
 
 static DECLARE_DELAYED_WORK(purge_orig_wq, purge_orig);
 
@@ -97,6 +98,7 @@  static void free_orig_node(void *data)
 		kfree(neigh_node);
 	}
 
+	frag_list_free(&orig_node->frag_list);
 	hna_global_del_orig(orig_node, "originator timed out");
 
 	kfree(orig_node->bcast_own);
@@ -159,6 +161,10 @@  struct orig_node *get_orig_node(uint8_t *addr)
 
 	size = bat_priv->num_ifaces * sizeof(uint8_t);
 	orig_node->bcast_own_sum = kzalloc(size, GFP_ATOMIC);
+
+	INIT_LIST_HEAD(&orig_node->frag_list);
+	orig_node->last_frag_packet = 0;
+
 	if (!orig_node->bcast_own_sum)
 		goto free_bcast_own;
 
@@ -275,6 +281,10 @@  void purge_orig(struct work_struct *work)
 			hash_remove_bucket(orig_hash, &hashit);
 			free_orig_node(orig_node);
 		}
+
+		if (time_after(jiffies, (orig_node->last_frag_packet +
+			msecs_to_jiffies(FRAG_TIMEOUT))))
+			frag_list_free(&orig_node->frag_list);
 	}
 
 	spin_unlock_irqrestore(&orig_hash_lock, flags);
diff --git a/batman-adv/packet.h b/batman-adv/packet.h
index e94960d..ca8d478 100644
--- a/batman-adv/packet.h
+++ b/batman-adv/packet.h
@@ -24,14 +24,15 @@ 
 
 #define ETH_P_BATMAN  0x4305	/* unofficial/not registered Ethertype */
 
-#define BAT_PACKET    0x01
-#define BAT_ICMP      0x02
-#define BAT_UNICAST   0x03
-#define BAT_BCAST     0x04
-#define BAT_VIS       0x05
+#define BAT_PACKET       0x01
+#define BAT_ICMP         0x02
+#define BAT_UNICAST      0x03
+#define BAT_UNICAST_FRAG 0x04
+#define BAT_BCAST        0x05
+#define BAT_VIS          0x06
 
 /* this file is included by batctl which needs these defines */
-#define COMPAT_VERSION 10
+#define COMPAT_VERSION 12
 #define DIRECTLINK 0x40
 #define VIS_SERVER 0x20
 #define PRIMARIES_FIRST_HOP 0x10
@@ -47,6 +48,9 @@ 
 #define VIS_TYPE_SERVER_SYNC		0
 #define VIS_TYPE_CLIENT_UPDATE		1
 
+/* fragmentation defines */
+#define UNI_FRAG_HEAD 0x01
+
 struct batman_packet {
 	uint8_t  packet_type;
 	uint8_t  version;  /* batman version field */
@@ -98,6 +102,16 @@  struct unicast_packet {
 	uint8_t  ttl;
 } __attribute__((packed));
 
+struct unicast_frag_packet {
+	uint8_t  packet_type;
+	uint8_t  version;  /* batman version field */
+	uint8_t  dest[6];
+	uint8_t  ttl;
+	uint8_t  flags;
+	uint8_t  orig[6];
+	uint16_t seqno;
+} __attribute__((packed));
+
 struct bcast_packet {
 	uint8_t  packet_type;
 	uint8_t  version;  /* batman version field */
diff --git a/batman-adv/routing.c b/batman-adv/routing.c
index 5dd4295..53fe0be 100644
--- a/batman-adv/routing.c
+++ b/batman-adv/routing.c
@@ -34,6 +34,7 @@ 
 #include "aggregation.h"
 #include "compat.h"
 #include "gateway_client.h"
+#include "fragmentation.h"
 
 static DECLARE_WAIT_QUEUE_HEAD(thread_wait);
 
@@ -1105,43 +1106,18 @@  struct neigh_node *find_router(struct orig_node *orig_node,
 	return router;
 }
 
-int recv_unicast_packet(struct sk_buff *skb, struct batman_if *recv_if)
+static int route_unicast_packet(struct sk_buff *skb, struct batman_if *recv_if,
+		int hdr_size)
 {
-	struct unicast_packet *unicast_packet;
 	struct orig_node *orig_node;
 	struct neigh_node *router;
-	struct ethhdr *ethhdr;
 	struct batman_if *batman_if;
 	struct sk_buff *skb_old;
 	uint8_t dstaddr[ETH_ALEN];
-	int hdr_size = sizeof(struct unicast_packet);
 	unsigned long flags;
-
-	/* drop packet if it has not necessary minimum size */
-	if (skb_headlen(skb) < hdr_size)
-		return NET_RX_DROP;
-
-	ethhdr = (struct ethhdr *) skb_mac_header(skb);
-
-	/* packet with unicast indication but broadcast recipient */
-	if (is_bcast(ethhdr->h_dest))
-		return NET_RX_DROP;
-
-	/* packet with broadcast sender address */
-	if (is_bcast(ethhdr->h_source))
-		return NET_RX_DROP;
-
-	/* not for me */
-	if (!is_my_mac(ethhdr->h_dest))
-		return NET_RX_DROP;
-
-	unicast_packet = (struct unicast_packet *) skb->data;
-
-	/* packet for me */
-	if (is_my_mac(unicast_packet->dest)) {
-		interface_rx(skb, hdr_size);
-		return NET_RX_SUCCESS;
-	}
+	struct unicast_packet *unicast_packet =
+		(struct unicast_packet *) skb->data;
+	struct ethhdr *ethhdr = (struct ethhdr *) skb_mac_header(skb);
 
 	/* TTL exceeded */
 	if (unicast_packet->ttl < 2) {
@@ -1172,7 +1148,7 @@  int recv_unicast_packet(struct sk_buff *skb, struct batman_if *recv_if)
 	spin_unlock_irqrestore(&orig_hash_lock, flags);
 
 	/* create a copy of the skb, if needed, to modify it. */
-	if (!skb_clone_writable(skb, sizeof(struct unicast_packet))) {
+	if (!skb_clone_writable(skb, hdr_size)) {
 		skb_old = skb;
 		skb = skb_copy(skb, GFP_ATOMIC);
 		if (!skb)
@@ -1191,6 +1167,112 @@  int recv_unicast_packet(struct sk_buff *skb, struct batman_if *recv_if)
 	return NET_RX_SUCCESS;
 }
 
+int recv_unicast_packet(struct sk_buff *skb, struct batman_if *recv_if)
+{
+	struct unicast_packet *unicast_packet;
+	struct ethhdr *ethhdr;
+	int hdr_size = sizeof(struct unicast_packet);
+
+	/* drop packet if it has not necessary minimum size */
+	if (skb_headlen(skb) < hdr_size)
+		return NET_RX_DROP;
+
+	ethhdr = (struct ethhdr *) skb_mac_header(skb);
+
+	/* packet with unicast indication but broadcast recipient */
+	if (is_bcast(ethhdr->h_dest))
+		return NET_RX_DROP;
+
+	/* packet with broadcast sender address */
+	if (is_bcast(ethhdr->h_source))
+		return NET_RX_DROP;
+
+	/* not for me */
+	if (!is_my_mac(ethhdr->h_dest))
+		return NET_RX_DROP;
+
+	unicast_packet = (struct unicast_packet *) skb->data;
+
+	/* packet for me */
+	if (is_my_mac(unicast_packet->dest)) {
+		interface_rx(skb, hdr_size);
+		return NET_RX_SUCCESS;
+	}
+
+	return route_unicast_packet(skb, recv_if, hdr_size);
+}
+
+int recv_ucast_frag_packet(struct sk_buff *skb, struct batman_if *recv_if)
+{
+	struct unicast_frag_packet *unicast_packet;
+	struct orig_node *orig_node;
+	struct ethhdr *ethhdr;
+	struct frag_packet_list_entry *tmp_frag_entry;
+	int hdr_size = sizeof(struct unicast_frag_packet);
+	unsigned long flags;
+
+	/* drop packet if it has not necessary minimum size */
+	if (skb_headlen(skb) < hdr_size)
+		return NET_RX_DROP;
+
+	ethhdr = (struct ethhdr *) skb_mac_header(skb);
+
+	/* packet with unicast indication but broadcast recipient */
+	if (is_bcast(ethhdr->h_dest))
+		return NET_RX_DROP;
+
+	/* packet with broadcast sender address */
+	if (is_bcast(ethhdr->h_source))
+		return NET_RX_DROP;
+
+	/* not for me */
+	if (!is_my_mac(ethhdr->h_dest))
+		return NET_RX_DROP;
+
+	unicast_packet = (struct unicast_frag_packet *) skb->data;
+
+	/* packet for me */
+	if (is_my_mac(unicast_packet->dest)) {
+
+		spin_lock_irqsave(&orig_hash_lock, flags);
+		orig_node = ((struct orig_node *)
+			hash_find(orig_hash, unicast_packet->orig));
+
+		if (!orig_node) {
+			pr_warning("couldn't find orig node for "
+				"fragmentation\n");
+			spin_unlock_irqrestore(&orig_hash_lock, flags);
+			return NET_RX_DROP;
+		}
+
+		orig_node->last_frag_packet = jiffies;
+
+		if (list_empty(&orig_node->frag_list))
+			create_frag_buffer(&orig_node->frag_list);
+
+		tmp_frag_entry =
+			search_frag_packet(&orig_node->frag_list,
+			unicast_packet);
+
+		if (!tmp_frag_entry) {
+			create_frag_entry(&orig_node->frag_list, skb);
+			spin_unlock_irqrestore(&orig_hash_lock, flags);
+			return NET_RX_SUCCESS;
+		}
+
+		skb = merge_frag_packet(&orig_node->frag_list,
+			tmp_frag_entry, skb);
+		spin_unlock_irqrestore(&orig_hash_lock, flags);
+		if (!skb)
+			return NET_RX_DROP;
+
+		interface_rx(skb, hdr_size);
+		return NET_RX_SUCCESS;
+	}
+
+	return route_unicast_packet(skb, recv_if, hdr_size);
+}
+
 int recv_bcast_packet(struct sk_buff *skb)
 {
 	struct orig_node *orig_node;
diff --git a/batman-adv/routing.h b/batman-adv/routing.h
index 3eac64e..81c684f 100644
--- a/batman-adv/routing.h
+++ b/batman-adv/routing.h
@@ -34,6 +34,7 @@  void update_routes(struct orig_node *orig_node,
 				unsigned char *hna_buff, int hna_buff_len);
 int recv_icmp_packet(struct sk_buff *skb);
 int recv_unicast_packet(struct sk_buff *skb, struct batman_if *recv_if);
+int recv_ucast_frag_packet(struct sk_buff *skb, struct batman_if *recv_if);
 int recv_bcast_packet(struct sk_buff *skb);
 int recv_vis_packet(struct sk_buff *skb);
 int recv_bat_packet(struct sk_buff *skb,
diff --git a/batman-adv/soft-interface.c b/batman-adv/soft-interface.c
index 0d89597..a906134 100644
--- a/batman-adv/soft-interface.c
+++ b/batman-adv/soft-interface.c
@@ -32,6 +32,7 @@ 
 #include <linux/ethtool.h>
 #include <linux/etherdevice.h>
 #include "compat.h"
+#include "fragmentation.h"
 
 static uint32_t bcast_seqno = 1; /* give own bcast messages seq numbers to avoid
 				  * broadcast storms */
@@ -130,6 +131,7 @@  static int interface_change_mtu(struct net_device *dev, int new_mtu)
 int interface_tx(struct sk_buff *skb, struct net_device *dev)
 {
 	struct unicast_packet *unicast_packet;
+	struct unicast_frag_packet *ucast_frag1, *ucast_frag2;
 	struct bcast_packet *bcast_packet;
 	struct orig_node *orig_node;
 	struct neigh_node *router;
@@ -137,9 +139,11 @@  int interface_tx(struct sk_buff *skb, struct net_device *dev)
 	struct bat_priv *priv = netdev_priv(dev);
 	struct batman_if *batman_if;
 	struct bat_priv *bat_priv;
+	struct sk_buff *frag_skb;
 	uint8_t dstaddr[6];
 	int data_len = skb->len;
 	unsigned long flags;
+	int hdr_len;
 	bool bcast_dst = false, do_bcast = true;
 
 	if (atomic_read(&module_state) != MODULE_ACTIVE)
@@ -216,20 +220,66 @@  int interface_tx(struct sk_buff *skb, struct net_device *dev)
 		if (batman_if->if_status != IF_ACTIVE)
 			goto dropped;
 
-		if (my_skb_push(skb, sizeof(struct unicast_packet)) < 0)
-			goto dropped;
+		if (atomic_read(&bat_priv->frag_enabled) &&
+		   data_len + sizeof(struct unicast_packet) >
+		   batman_if->net_dev->mtu) {
+
+			hdr_len = sizeof(struct unicast_frag_packet);
+
+			frag_skb = dev_alloc_skb(data_len - (data_len / 2) +
+				hdr_len);
+			skb_split(skb, frag_skb, data_len / 2);
+
+			if (my_skb_push(frag_skb, hdr_len) < 0 ||
+				my_skb_push(skb, hdr_len) < 0) {
+
+				kfree_skb(frag_skb);
+				goto dropped;
+			}
+
+			ucast_frag1 = (struct unicast_frag_packet *)skb->data;
+			ucast_frag2 =
+				(struct unicast_frag_packet *)frag_skb->data;
+
+			ucast_frag1->version = COMPAT_VERSION;
+			ucast_frag1->packet_type = BAT_UNICAST_FRAG;
+			ucast_frag1->ttl = TTL;
+			memcpy(ucast_frag1->orig,
+				batman_if->net_dev->dev_addr, ETH_ALEN);
+			memcpy(ucast_frag1->dest, orig_node->orig, ETH_ALEN);
+
+			memcpy(ucast_frag2, ucast_frag1,
+			       sizeof(struct unicast_frag_packet));
+
+			ucast_frag1->flags |= UNI_FRAG_HEAD;
+			ucast_frag2->flags &= ~UNI_FRAG_HEAD;
+
+			ucast_frag1->seqno = htons((uint16_t)atomic_inc_return(
+				&batman_if->frag_seqno));
+
+			ucast_frag2->seqno = htons((uint16_t)atomic_inc_return(
+				&batman_if->frag_seqno));
+
+			send_skb_packet(skb, batman_if, dstaddr);
+			send_skb_packet(frag_skb, batman_if, dstaddr);
+
+		} else {
+
+			if (my_skb_push(skb, sizeof(struct unicast_packet)) < 0)
+				goto dropped;
 
-		unicast_packet = (struct unicast_packet *)skb->data;
+			unicast_packet = (struct unicast_packet *)skb->data;
 
-		unicast_packet->version = COMPAT_VERSION;
-		/* batman packet type: unicast */
-		unicast_packet->packet_type = BAT_UNICAST;
-		/* set unicast ttl */
-		unicast_packet->ttl = TTL;
-		/* copy the destination for faster routing */
-		memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
+			unicast_packet->version = COMPAT_VERSION;
+			/* batman packet type: unicast */
+			unicast_packet->packet_type = BAT_UNICAST;
+			/* set unicast ttl */
+			unicast_packet->ttl = TTL;
+			/* copy the destination for faster routing */
+			memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
 
-		send_skb_packet(skb, batman_if, dstaddr);
+			send_skb_packet(skb, batman_if, dstaddr);
+		}
 	}
 
 	priv->stats.tx_packets++;
@@ -309,7 +359,9 @@  void interface_setup(struct net_device *dev)
 #endif
 	dev->destructor = free_netdev;
 
-	dev->mtu = hardif_min_mtu();
+	dev->mtu = ETH_DATA_LEN;	/* can't call min_mtu, because the
+					 * needed variables have not been
+					 * initiatlized yet */
 	dev->hard_header_len = BAT_HEADER_LEN; /* reserve more space in the
 						* skbuff for our header */
 
diff --git a/batman-adv/types.h b/batman-adv/types.h
index 9cd19b7..e3c4d2d 100644
--- a/batman-adv/types.h
+++ b/batman-adv/types.h
@@ -41,6 +41,7 @@  struct batman_if {
 	char addr_str[ETH_STR_LEN];
 	struct net_device *net_dev;
 	atomic_t seqno;
+	atomic_t frag_seqno;
 	unsigned char *packet_buff;
 	int packet_len;
 	struct kobject *hardif_obj;
@@ -82,6 +83,8 @@  struct orig_node {
 	TYPE_OF_WORD bcast_bits[NUM_WORDS];
 	uint32_t last_bcast_seqno;
 	struct list_head neigh_list;
+	struct list_head frag_list;
+	unsigned long last_frag_packet;
 	struct {
 		uint8_t candidates;
 		struct neigh_node *selected;
@@ -118,6 +121,7 @@  struct bat_priv {
 	struct net_device_stats stats;
 	atomic_t aggregation_enabled;
 	atomic_t bonding_enabled;
+	atomic_t frag_enabled;
 	atomic_t vis_mode;
 	atomic_t gw_mode;
 	atomic_t gw_class;
@@ -192,4 +196,10 @@  struct debug_log {
 	wait_queue_head_t queue_wait;
 };
 
+struct frag_packet_list_entry {
+	struct list_head list;
+	uint16_t seqno;
+	struct sk_buff *skb;
+};
+
 #endif /* _NET_BATMAN_ADV_TYPES_H_ */