diff --git a/Makefile.kbuild b/Makefile.kbuild
index bd7e93c..d626513 100644
--- a/Makefile.kbuild
+++ b/Makefile.kbuild
@@ -51,3 +51,4 @@ batman-adv-y += translation-table.o
 batman-adv-y += unicast.o
 batman-adv-y += vis.o
 batman-adv-y += compat.o
+batman-adv-y += bridge_loop_avoidance.o
diff --git a/bat_sysfs.c b/bat_sysfs.c
index c25492f..ec2e437 100644
--- a/bat_sysfs.c
+++ b/bat_sysfs.c
@@ -390,7 +390,7 @@ BAT_ATTR_UINT(gw_sel_class, S_IRUGO | S_IWUSR, 1, TQ_MAX_VALUE,
 static BAT_ATTR(gw_bandwidth, S_IRUGO | S_IWUSR, show_gw_bwidth,
 		store_gw_bwidth);
 #ifdef CONFIG_BATMAN_ADV_DEBUG
-BAT_ATTR_UINT(log_level, S_IRUGO | S_IWUSR, 0, 7, NULL);
+BAT_ATTR_UINT(log_level, S_IRUGO | S_IWUSR, 0, 15, NULL);
 #endif
 
 static struct bat_attribute *mesh_attrs[] = {
diff --git a/bridge_loop_avoidance.c b/bridge_loop_avoidance.c
new file mode 100644
index 0000000..f18774f
--- /dev/null
+++ b/bridge_loop_avoidance.c
@@ -0,0 +1,1310 @@
+/*
+ * Copyright (C) 2011 B.A.T.M.A.N. contributors:
+ *
+ * Simon Wunderlich
+ *
+ * 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 "hash.h"
+#include "hard-interface.h"
+#include "originator.h"
+#include "bridge_loop_avoidance.h"
+#include "send.h"
+
+#include <linux/etherdevice.h>
+#include <linux/crc16.h>
+#include <linux/if_arp.h>
+#include <net/arp.h>
+#include <linux/if_vlan.h>
+
+static const uint8_t claim_dest[6] = {0xff, 0x43, 0x05, 0x00, 0x00, 0x00};
+static const uint8_t announce_mac[4] = {0x43, 0x05, 0x43, 0x05};
+
+static void bla_periodic_work(struct work_struct *work);
+static void bla_send_announce(struct bat_priv *bat_priv,
+		struct backbone_gw *backbone_gw);
+
+/* return the index of the claim */
+static inline uint32_t choose_claim(const void *data, uint32_t size)
+{
+	const unsigned char *key = data;
+	uint32_t hash = 0;
+	size_t i;
+
+	for (i = 0; i < ETH_ALEN + sizeof(short); i++) {
+		hash += key[i];
+		hash += (hash << 10);
+		hash ^= (hash >> 6);
+	}
+
+	hash += (hash << 3);
+	hash ^= (hash >> 11);
+	hash += (hash << 15);
+
+	return hash % size;
+}
+
+/* return the index of the backbone gateway */
+static inline uint32_t choose_backbone_gw(const void *data, uint32_t size)
+{
+	const unsigned char *key = data;
+	uint32_t hash = 0;
+	size_t i;
+
+	for (i = 0; i < ETH_ALEN + sizeof(short); i++) {
+		hash += key[i];
+		hash += (hash << 10);
+		hash ^= (hash >> 6);
+	}
+
+	hash += (hash << 3);
+	hash ^= (hash >> 11);
+	hash += (hash << 15);
+
+	return hash % size;
+}
+
+
+/* compares address and vid of two backbone gws */
+static int compare_backbone_gw(const struct hlist_node *node, const void *data2)
+{
+	const void *data1 = container_of(node, struct backbone_gw,
+					 hash_entry);
+
+	return (memcmp(data1, data2, ETH_ALEN + sizeof(short)) == 0 ? 1 : 0);
+}
+
+/* compares address and vid of two claims */
+static int compare_claim(const struct hlist_node *node, const void *data2)
+{
+	const void *data1 = container_of(node, struct claim,
+					 hash_entry);
+
+	return (memcmp(data1, data2, ETH_ALEN + sizeof(short)) == 0 ? 1 : 0);
+}
+
+/* free a backbone gw */
+static void backbone_gw_free_ref(struct backbone_gw *backbone_gw)
+{
+	if (atomic_dec_and_test(&backbone_gw->refcount))
+		kfree_rcu(backbone_gw, rcu);
+}
+
+/* finally deinitialize the claim */
+static void claim_free_rcu(struct rcu_head *rcu)
+{
+	struct claim *claim;
+
+	claim = container_of(rcu, struct claim, rcu);
+
+	backbone_gw_free_ref(claim->backbone_gw);
+	kfree(claim);
+}
+
+/* free a claim, call claim_free_rcu if its the last reference */
+static void claim_free_ref(struct claim *claim)
+{
+	if (atomic_dec_and_test(&claim->refcount))
+		call_rcu(&claim->rcu, claim_free_rcu);
+}
+
+/*
+ * @bat_priv: the bat priv with all the soft interface information
+ * @data: search data (may be local/static data)
+ *
+ * looks for a claim in the hash, and returns it if found
+ * or NULL otherwise.
+ */
+
+static struct claim *claim_hash_find(struct bat_priv *bat_priv,
+		struct claim *data)
+{
+	struct hashtable_t *hash = bat_priv->claim_hash;
+	struct hlist_head *head;
+	struct hlist_node *node;
+	struct claim *claim;
+	struct claim *claim_tmp = NULL;
+	int index;
+
+	if (!hash)
+		return NULL;
+
+	index = choose_claim(data, hash->size);
+	head = &hash->table[index];
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(claim, node, head, hash_entry) {
+		if (!compare_claim(&claim->hash_entry, data))
+			continue;
+
+		if (!atomic_inc_not_zero(&claim->refcount))
+			continue;
+
+		claim_tmp = claim;
+		break;
+	}
+	rcu_read_unlock();
+
+	return claim_tmp;
+}
+
+/*
+ * @bat_priv: the bat priv with all the soft interface information
+ * @addr: the address of the originator
+ * @vid: the VLAN ID
+ *
+ * looks for a claim in the hash, and returns it if found
+ * or NULL otherwise.
+ */
+
+static struct backbone_gw *backbone_hash_find(struct bat_priv *bat_priv,
+		uint8_t *addr, short vid)
+{
+	struct hashtable_t *hash = bat_priv->backbone_hash;
+	struct hlist_head *head;
+	struct hlist_node *node;
+	struct backbone_gw search_entry, *backbone_gw;
+	struct backbone_gw *backbone_gw_tmp = NULL;
+	int index;
+
+	if (!hash)
+		return NULL;
+
+	memcpy(search_entry.orig, addr, ETH_ALEN);
+	search_entry.vid = vid;
+
+	index = choose_backbone_gw(&search_entry, hash->size);
+	head = &hash->table[index];
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(backbone_gw, node, head, hash_entry) {
+		if (!compare_backbone_gw(&backbone_gw->hash_entry,
+					&search_entry))
+			continue;
+
+		if (!atomic_inc_not_zero(&backbone_gw->refcount))
+			continue;
+
+		backbone_gw_tmp = backbone_gw;
+		break;
+	}
+	rcu_read_unlock();
+
+	return backbone_gw_tmp;
+}
+
+/* delete all claims for a backbone */
+static void bla_del_backbone_claims(struct backbone_gw *backbone_gw)
+{
+	struct hashtable_t *hash;
+	struct hlist_node *node, *node_tmp;
+	struct hlist_head *head;
+	struct claim *claim;
+	int i;
+	spinlock_t *list_lock;	/* protects write access to the hash lists */
+
+	hash = backbone_gw->bat_priv->claim_hash;
+	if (!hash)
+		return;
+
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+		list_lock = &hash->list_locks[i];
+
+		spin_lock_bh(list_lock);
+		hlist_for_each_entry_safe(claim, node, node_tmp,
+					 head, hash_entry) {
+
+			if (claim->backbone_gw != backbone_gw)
+				continue;
+
+			claim_free_ref(claim);
+			hlist_del_rcu(node);
+		}
+		spin_unlock_bh(list_lock);
+	}
+
+	/* all claims gone, intialize CRC */
+	backbone_gw->crc = BLA_CRC_INIT;
+}
+
+/*
+ * @bat_priv: the bat priv with all the soft interface information
+ * @orig: the mac address to be announced within the claim
+ * @vid: the VLAN ID
+ * @claimtype: the type of the claim (CLAIM, UNCLAIM, ANNOUNCE, ...)
+ *
+ * sends a claim frame according to the provided info.
+ */
+
+static void bla_send_claim(struct bat_priv *bat_priv, uint8_t *mac,
+		short vid, int claimtype)
+{
+	struct sk_buff *skb;
+	struct ethhdr *ethhdr;
+	struct hard_iface *primary_if;
+	struct net_device *soft_iface;
+	uint8_t *hw_src;
+	struct bla_claim_dst local_claim_dest;
+	uint32_t zeroip = 0;
+
+	primary_if = primary_if_get_selected(bat_priv);
+	if (!primary_if)
+		return;
+
+	memcpy(&local_claim_dest, claim_dest,
+			sizeof(local_claim_dest));
+	local_claim_dest.type = claimtype;
+
+	soft_iface = primary_if->soft_iface;
+
+	skb = arp_create(ARPOP_REPLY, ETH_P_ARP,
+		zeroip,				/* IP DST: 0.0.0.0 */
+		primary_if->soft_iface,
+		zeroip,				/* IP SRC: 0.0.0.0 */
+		NULL,				/* Ethernet DST: Broadcast */
+		primary_if->net_dev->dev_addr,	/* Ethernet SRC/HW SRC:
+						 * originator mac */
+		(uint8_t *)&local_claim_dest	/* HW DST: FF:43:05:XX:00:00
+						 * with XX   = claim type */
+		);
+
+	if (!skb)
+		goto out;
+
+	ethhdr = (struct ethhdr *)skb->data;
+	hw_src = (uint8_t *) ethhdr
+		+ sizeof(struct ethhdr) + sizeof(struct arphdr);
+
+	/* now we pretend that the client would have sent this ... */
+	switch (claimtype) {
+	case CLAIM_TYPE_ADD:
+		/*
+		 * normal claim frame
+		 * set Ethernet SRC to the clients mac
+		 */
+		memcpy(ethhdr->h_source, mac, ETH_ALEN);
+		bat_dbg(DBG_BLA, bat_priv,
+			"bla_send_claim(): CLAIM %pM on vid %d\n", mac, vid);
+		break;
+	case CLAIM_TYPE_DEL:
+		/*
+		 * unclaim frame
+		 * set HW SRC to the clients mac
+		 */
+		memcpy(hw_src, mac, ETH_ALEN);
+		bat_dbg(DBG_BLA, bat_priv,
+			"bla_send_claim(): UNCLAIM %pM on vid %d\n", mac, vid);
+		break;
+	case CLAIM_TYPE_ANNOUNCE:
+		/*
+		 * announcement frame
+		 * set HW SRC to the special mac containg the crc
+		 */
+		memcpy(hw_src, mac, ETH_ALEN);
+		bat_dbg(DBG_BLA, bat_priv,
+			"bla_send_claim(): ANNOUNCE of %pM on vid %d\n",
+			ethhdr->h_source, vid);
+		break;
+	case CLAIM_TYPE_REQUEST:
+		/*
+		 * request frame
+		 * set HW SRC to the special mac containg the crc
+		 */
+		memcpy(hw_src, mac, ETH_ALEN);
+		memcpy(ethhdr->h_dest, mac, ETH_ALEN);
+		bat_dbg(DBG_BLA, bat_priv,
+			"bla_send_claim(): REQUEST of %pM to %pMon vid %d\n",
+			ethhdr->h_source, ethhdr->h_dest, vid);
+		break;
+
+	}
+
+	if (vid != -1)
+		skb = vlan_insert_tag(skb, vid);
+
+	skb_reset_mac_header(skb);
+	skb->protocol = eth_type_trans(skb, soft_iface);
+	bat_priv->stats.rx_packets++;
+	bat_priv->stats.rx_bytes += skb->len + sizeof(struct ethhdr);
+	soft_iface->last_rx = jiffies;
+
+	netif_rx(skb);
+out:
+	if (primary_if)
+		hardif_free_ref(primary_if);
+}
+
+/*
+ * @bat_priv: the bat priv with all the soft interface information
+ * @orig: the mac address of the originator
+ * @vid: the VLAN ID
+ *
+ * searches for the backbone gw or creates a new one if it could not
+ * be found.
+ */
+
+static struct backbone_gw *bla_get_backbone_gw(struct bat_priv *bat_priv,
+		uint8_t *orig, short vid)
+{
+	struct backbone_gw *entry;
+	int hash_added;
+
+	entry = backbone_hash_find(bat_priv, orig, vid);
+
+	if (entry)
+		return entry;
+
+	bat_dbg(DBG_BLA, bat_priv,
+		"bla_get_backbone_gw(): not found (%pM, %d),"
+		" creating new entry\n", orig, vid);
+
+	entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
+	if (!entry)
+		return NULL;
+
+	entry->vid = vid;
+	entry->lasttime = jiffies;
+	entry->crc = BLA_CRC_INIT;
+	entry->bat_priv = bat_priv;
+	atomic_set(&entry->request_sent, 0);
+	memcpy(entry->orig, orig, ETH_ALEN);
+
+	/* one for the hash, one for returning */
+	atomic_set(&entry->refcount, 2);
+
+	hash_added = hash_add(bat_priv->backbone_hash, compare_backbone_gw,
+			choose_backbone_gw, entry, &entry->hash_entry);
+
+	if (unlikely(hash_added != 0)) {
+		/* hash failed, free the structure */
+		kfree(entry);
+		return NULL;
+	}
+
+	return entry;
+}
+
+/*
+ * update or add the own backbone gw to make sure we announce
+ * where we receive other backbone gws
+ */
+static void bla_update_own_backbone_gw(struct bat_priv *bat_priv,
+		struct hard_iface *primary_if, short vid)
+{
+	struct backbone_gw *backbone_gw;
+
+	backbone_gw = bla_get_backbone_gw(bat_priv,
+			primary_if->net_dev->dev_addr, vid);
+	if (unlikely(!backbone_gw))
+		return;
+
+	backbone_gw->lasttime = jiffies;
+	backbone_gw_free_ref(backbone_gw);
+}
+
+/*
+ * @bat_priv: the bat priv with all the soft interface information
+ * @vid: the vid where the request came on
+ *
+ * Repeat all of our own claims, and finally send an ANNOUNCE frame
+ * to allow the requester another check if the CRC is correct now.
+ */
+
+static void bla_answer_request(struct bat_priv *bat_priv,
+		struct hard_iface *primary_if, short vid)
+{
+	struct hlist_node *node;
+	struct hlist_head *head;
+	struct hashtable_t *hash;
+	struct claim *claim;
+	struct backbone_gw *backbone_gw;
+	int i;
+
+	bat_dbg(DBG_BLA, bat_priv,
+		"bla_answer_request(): received a "
+		"claim request, send all of our own claims again\n");
+
+	backbone_gw = backbone_hash_find(bat_priv,
+			primary_if->net_dev->dev_addr, vid);
+	if (!backbone_gw)
+		return;
+
+	hash = bat_priv->claim_hash;
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+
+		rcu_read_lock();
+		hlist_for_each_entry_rcu(claim, node,
+					 head, hash_entry) {
+			/* only own claims are interesting */
+			if (claim->backbone_gw != backbone_gw)
+				continue;
+
+			bla_send_claim(bat_priv, claim->addr, claim->vid,
+					CLAIM_TYPE_ADD);
+		}
+		rcu_read_unlock();
+	}
+
+	/* finally, send an announcement frame */
+	bla_send_announce(bat_priv, backbone_gw);
+	backbone_gw_free_ref(backbone_gw);
+}
+
+/*
+ * @backbone_gw: the backbone gateway from whom we are out of sync
+ *
+ * When the crc is wrong, ask the backbone gateway for a full table update.
+ * After the request, it will repeat all of his own claims and finally
+ * send an announcement claim with which we can check again.
+ */
+
+static void bla_send_request(struct backbone_gw *backbone_gw)
+{
+	/* first, remove all old entries */
+	bla_del_backbone_claims(backbone_gw);
+
+	bat_dbg(DBG_BLA, backbone_gw->bat_priv,
+		"Sending REQUEST to %pM\n",
+		backbone_gw->orig);
+
+	/* send request */
+	bla_send_claim(backbone_gw->bat_priv, backbone_gw->orig,
+			backbone_gw->vid, CLAIM_TYPE_REQUEST);
+
+	/* no local broadcasts should be sent or received, for now. */
+	if (!atomic_read(&backbone_gw->request_sent)) {
+		atomic_inc(&backbone_gw->bat_priv->bla_num_requests);
+		atomic_set(&backbone_gw->request_sent, 1);
+	}
+}
+
+/*
+ * @bat_priv: the bat priv with all the soft interface information
+ * @backbone_gw: our backbone gateway which should be announced
+ *
+ * This function sends an announcement. It is called from multiple
+ * places.
+ */
+static void bla_send_announce(struct bat_priv *bat_priv,
+		struct backbone_gw *backbone_gw)
+{
+	uint8_t mac[ETH_ALEN];
+	uint16_t crc;
+
+	memcpy(mac, announce_mac, 4);
+	crc = htons(backbone_gw->crc);
+	memcpy(&mac[4], (uint8_t *) &crc, 2);
+
+	bla_send_claim(bat_priv, mac, backbone_gw->vid, CLAIM_TYPE_ANNOUNCE);
+
+}
+
+/*
+ * @bat_priv: the bat priv with all the soft interface information
+ * @mac: the mac address of the claim
+ * @vid: the VLAN ID of the frame
+ * @backbone_gw: the backbone gateway which claims it
+ *
+ * Adds a claim in the claim hash.
+ */
+
+static void bla_add_claim(struct bat_priv *bat_priv, const uint8_t *mac,
+		const short vid, struct backbone_gw *backbone_gw)
+{
+	struct claim *claim;
+	struct claim search_claim;
+	int hash_added;
+
+	memcpy(search_claim.addr, mac, ETH_ALEN);
+	search_claim.vid = vid;
+	claim = claim_hash_find(bat_priv, &search_claim);
+
+	/* create a new claim entry if it does not exist yet. */
+	if (!claim) {
+		claim = kzalloc(sizeof(*claim), GFP_ATOMIC);
+		if (!claim)
+			return;
+
+		memcpy(claim->addr, mac, ETH_ALEN);
+		claim->vid = vid;
+		claim->lasttime = jiffies;
+		claim->backbone_gw = backbone_gw;
+
+		atomic_set(&claim->refcount, 2);
+		bat_dbg(DBG_BLA, bat_priv,
+			"bla_add_claim(): adding new entry %pM, vid %d to hash ...\n",
+			mac, vid);
+		hash_added = hash_add(bat_priv->claim_hash, compare_claim,
+			choose_claim, claim, &claim->hash_entry);
+
+		if (unlikely(hash_added != 0)) {
+			/* only local changes happened. */
+			kfree(claim);
+			return;
+		}
+	} else {
+		claim->lasttime = jiffies;
+		if (claim->backbone_gw == backbone_gw)
+			/* no need to register a new backbone */
+			goto claim_free_ref;
+
+		bat_dbg(DBG_BLA, bat_priv,
+			"bla_add_claim(): changing ownership for %pM, vid %d\n",
+			mac, vid);
+
+		claim->backbone_gw->crc ^=
+			crc16(0, claim->addr, ETH_ALEN);
+		backbone_gw_free_ref(claim->backbone_gw);
+
+	}
+	/* set (new) backbone gw */
+	atomic_inc(&backbone_gw->refcount);
+	claim->backbone_gw = backbone_gw;
+
+	backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);
+	backbone_gw->lasttime = jiffies;
+
+claim_free_ref:
+	claim_free_ref(claim);
+}
+
+/*
+ * Delete a claim from the claim hash which has the
+ * given mac address and vid.
+ */
+static void bla_del_claim(struct bat_priv *bat_priv, const uint8_t *mac,
+		const short vid)
+{
+	struct claim search_claim, *claim;
+
+	memcpy(search_claim.addr, mac, ETH_ALEN);
+	search_claim.vid = vid;
+	claim = claim_hash_find(bat_priv, &search_claim);
+	if (!claim)
+		return;
+
+	bat_dbg(DBG_BLA, bat_priv, "bla_del_claim(): %pM, vid %d\n", mac, vid);
+
+	hash_remove(bat_priv->claim_hash, compare_claim, choose_claim,
+		    claim);
+	claim_free_ref(claim); /* reference from the hash is gone */
+
+	claim->backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN);
+
+	/* don't need the reference from hash_find() anymore */
+	claim_free_ref(claim);
+}
+
+/* check for ANNOUNCE frame, return 1 if handled */
+static int handle_announce(struct bat_priv *bat_priv,
+		uint8_t *an_addr, uint8_t *backbone_addr, short vid)
+{
+	struct backbone_gw *backbone_gw;
+	uint16_t crc;
+
+	if (memcmp(an_addr, announce_mac, 4) != 0)
+		return 0;
+
+	backbone_gw = bla_get_backbone_gw(bat_priv, backbone_addr, vid);
+
+	if (unlikely(!backbone_gw))
+		return 1;
+
+
+	/* handle as ANNOUNCE frame */
+	backbone_gw->lasttime = jiffies;
+	crc = ntohs(*((uint16_t *) (&an_addr[4])));
+
+	bat_dbg(DBG_BLA, bat_priv,
+		"handle_announce(): ANNOUNCE vid %d (sent "
+		"by %pM)... CRC = %04x\n",
+		vid, backbone_gw->orig, crc);
+
+	if (backbone_gw->crc != crc) {
+		bat_dbg(DBG_BLA, backbone_gw->bat_priv,
+			"handle_announce(): CRC FAILED for %pM/%d"
+			"(my = %04x, sent = %04x)\n",
+			backbone_gw->orig, backbone_gw->vid,
+			backbone_gw->crc, crc);
+
+		bla_send_request(backbone_gw);
+	} else {
+		/* if we have sent a request and the crc was OK,
+		 * we can allow traffic again. */
+		if (atomic_read(&backbone_gw->request_sent)) {
+			atomic_dec(&backbone_gw->bat_priv->bla_num_requests);
+			atomic_set(&backbone_gw->request_sent, 0);
+		}
+	}
+
+	backbone_gw_free_ref(backbone_gw);
+	return 1;
+}
+
+/* check for REQUEST frame, return 1 if handled */
+static int handle_request(struct bat_priv *bat_priv,
+		struct hard_iface *primary_if, uint8_t *backbone_addr,
+		struct ethhdr *ethhdr, short vid)
+{
+	/* check for REQUEST frame */
+	if (!compare_eth(backbone_addr, ethhdr->h_dest))
+		return 0;
+
+	/* sanity check, this should not happen on a normal switch,
+	 * we ignore it in this case. */
+	if (!compare_eth(ethhdr->h_dest, primary_if->net_dev->dev_addr))
+		return 1;
+
+	bat_dbg(DBG_BLA, bat_priv,
+		"handle_request(): REQUEST vid %d (sent "
+		"by %pM)...\n",
+		vid, ethhdr->h_source);
+
+	bla_answer_request(bat_priv, primary_if, vid);
+	return 1;
+}
+
+/* check for UNCLAIM frame, return 1 if handled */
+static int handle_unclaim(struct bat_priv *bat_priv,
+		struct hard_iface *primary_if, uint8_t *backbone_addr,
+		uint8_t *claim_addr, short vid)
+{
+	struct backbone_gw *backbone_gw;
+
+	/* unclaim in any case if it is our own */
+	if (primary_if && compare_eth(backbone_addr,
+				primary_if->net_dev->dev_addr))
+		bla_send_claim(bat_priv, claim_addr, vid, CLAIM_TYPE_DEL);
+
+	backbone_gw = backbone_hash_find(bat_priv, backbone_addr, vid);
+
+	if (!backbone_gw)
+		return 1;
+
+	/* this must be an UNCLAIM frame */
+	bat_dbg(DBG_BLA, bat_priv, "handle_unclaim():"
+		"UNCLAIM %pM on vid %d (sent by %pM)...\n",
+		claim_addr, vid, backbone_gw->orig);
+
+	bla_del_claim(bat_priv, claim_addr, vid);
+	backbone_gw_free_ref(backbone_gw);
+	return 1;
+}
+
+/* check for CLAIM frame, return 1 if handled */
+static int handle_claim(struct bat_priv *bat_priv,
+		struct hard_iface *primary_if, uint8_t *backbone_addr,
+		uint8_t *claim_addr, short vid)
+{
+	struct backbone_gw *backbone_gw;
+
+	/* register the gateway if not yet available, and add the claim. */
+
+	backbone_gw = bla_get_backbone_gw(bat_priv, backbone_addr, vid);
+
+	if (unlikely(!backbone_gw))
+		return 1;
+
+	/* this must be a CLAIM frame */
+	bla_add_claim(bat_priv, claim_addr, vid, backbone_gw);
+	if (compare_eth(backbone_addr, primary_if->net_dev->dev_addr))
+		bla_send_claim(bat_priv, claim_addr, vid, CLAIM_TYPE_ADD);
+
+	/* TODO: we could call something like tt_local_del() here. */
+
+	backbone_gw_free_ref(backbone_gw);
+	return 1;
+}
+
+/*
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the frame to be checked
+ *
+ * Check if this is a claim frame, and process it accordingly.
+ *
+ * returns 1 if it was a claim frame, otherwise return 0 to
+ * tell the callee that it can use the frame on its own.
+ */
+
+static int bla_process_claim(struct bat_priv *bat_priv,
+		struct hard_iface *primary_if, struct sk_buff *skb)
+{
+	struct ethhdr *ethhdr;
+	struct vlan_ethhdr *vhdr;
+	struct arphdr *arphdr;
+	uint8_t *hw_src, *hw_dst;
+	struct bla_claim_dst *bla_dst;
+	uint16_t proto;
+	int headlen;
+	short vid = -1;
+
+	ethhdr = (struct ethhdr *)skb_mac_header(skb);
+
+	if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
+		vhdr = (struct vlan_ethhdr *) ethhdr;
+		vid = ntohs(vhdr->h_vlan_TCI) & VLAN_VID_MASK;
+		proto = ntohs(vhdr->h_vlan_encapsulated_proto);
+		headlen = sizeof(*vhdr);
+	} else {
+		proto = ntohs(ethhdr->h_proto);
+		headlen = sizeof(*ethhdr);
+	}
+
+	if (proto != ETH_P_ARP)
+		return 0; /* not a claim frame */
+
+	/* this must be a ARP frame. check if it is a claim. */
+
+	if (unlikely(!pskb_may_pull(skb, headlen + arp_hdr_len(skb->dev))))
+		return 0;
+
+	arphdr = (struct arphdr *) ((uint8_t *)ethhdr + headlen);
+
+	/* Check whether the ARP frame carries a valid
+	 * IP information */
+
+	if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
+		return 0;
+	if (arphdr->ar_pro != htons(ETH_P_IP))
+		return 0;
+	if (arphdr->ar_hln != ETH_ALEN)
+		return 0;
+	if (arphdr->ar_pln != 4)
+		return 0;
+
+	hw_src = (uint8_t *)arphdr + sizeof(struct arphdr);
+	hw_dst = hw_src + ETH_ALEN + 4;
+	bla_dst = (struct bla_claim_dst *) hw_dst;
+
+	/* check if it is a claim frame. */
+	if (memcmp(hw_dst, claim_dest, 3) != 0)
+		return 0;
+
+	/* become a backbone gw ourselves on this vlan if not happened yet */
+	bla_update_own_backbone_gw(bat_priv, primary_if, vid);
+
+	/* check for the different types of claim frames ... */
+	switch (bla_dst->type) {
+	case CLAIM_TYPE_ADD:
+		if (handle_claim(bat_priv, primary_if, hw_src,
+					ethhdr->h_source, vid))
+			return 1;
+		break;
+	case CLAIM_TYPE_DEL:
+		if (handle_unclaim(bat_priv, primary_if,
+					ethhdr->h_source, hw_src, vid))
+			return 1;
+		break;
+
+	case CLAIM_TYPE_ANNOUNCE:
+		if (handle_announce(bat_priv, hw_src, ethhdr->h_source, vid))
+			return 1;
+		break;
+	case CLAIM_TYPE_REQUEST:
+		if (handle_request(bat_priv, primary_if, hw_src, ethhdr, vid))
+			return 1;
+		break;
+	}
+
+	bat_dbg(DBG_BLA, bat_priv, "bla_process_claim(): ERROR - this looks"
+		"like a claim frame, but is useless. eth src"
+		"%pM on vid %d ...(hw_src %pM, hw_dst %pM)\n",
+		ethhdr->h_source, vid, hw_src, hw_dst);
+	return 1;
+}
+
+/*
+ * Check when we last heard from other nodes, and remove them in case of
+ * a time out, or clean all backbone gws if now is set.
+ */
+static void bla_purge_backbone_gw(struct bat_priv *bat_priv, int now)
+{
+	struct backbone_gw *backbone_gw;
+	struct hlist_node *node, *node_tmp;
+	struct hlist_head *head;
+	struct hashtable_t *hash;
+	spinlock_t *list_lock;	/* protects write access to the hash lists */
+	int i;
+
+	hash = bat_priv->backbone_hash;
+	if (!hash)
+		return;
+
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+		list_lock = &hash->list_locks[i];
+
+		spin_lock_bh(list_lock);
+		hlist_for_each_entry_safe(backbone_gw, node, node_tmp,
+					  head, hash_entry) {
+			if (now)
+				goto purge_now;
+			if (!time_after(jiffies, backbone_gw->lasttime
+				+ msecs_to_jiffies(BLA_BACKBONE_TIMEOUT)))
+				continue;
+
+			bat_dbg(DBG_BLA, backbone_gw->bat_priv,
+				"bla_purge_backbone_gw(): backbone gw %pM"
+				" timed out\n",	backbone_gw->orig);
+
+purge_now:
+			/* don't wait for the pending request anymore */
+			if (atomic_read(&backbone_gw->request_sent))
+				atomic_dec(&bat_priv->bla_num_requests);
+
+			bla_del_backbone_claims(backbone_gw);
+
+			hlist_del_rcu(node);
+			backbone_gw_free_ref(backbone_gw);
+		}
+		spin_unlock_bh(list_lock);
+	}
+}
+
+/**
+ * @bat_priv: the bat priv with all the soft interface information
+ * @primary_if: the selected primary interface, may be NULL if now is set
+ * @now: whether the whole hash shall be wiped now
+ *
+ * Check when we heard last time from our own claims, and remove them in case of
+ * a time out, or clean all claims if now is set
+ */
+static void bla_purge_claims(struct bat_priv *bat_priv,
+		struct hard_iface *primary_if, int now)
+{
+	struct claim *claim;
+	struct hlist_node *node;
+	struct hlist_head *head;
+	struct hashtable_t *hash;
+	int i;
+
+	hash = bat_priv->claim_hash;
+	if (!hash)
+		return;
+
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+
+		rcu_read_lock();
+		hlist_for_each_entry_rcu(claim, node, head, hash_entry) {
+			if (now)
+				goto purge_now;
+			if (!compare_eth(claim->backbone_gw->orig,
+					primary_if->net_dev->dev_addr))
+				continue;
+			if (!time_after(jiffies, claim->lasttime
+				+ msecs_to_jiffies(BLA_CLAIM_TIMEOUT)))
+				continue;
+
+			bat_dbg(DBG_BLA, bat_priv,
+				"bla_purge_claims(): %pM, vid %d, time out\n",
+				claim->addr, claim->vid);
+
+purge_now:
+			handle_unclaim(bat_priv, primary_if,
+				claim->backbone_gw->orig,
+				claim->addr, claim->vid);
+		}
+		rcu_read_unlock();
+	}
+}
+
+/**
+ * @bat_priv: the bat priv with all the soft interface information
+ * @primary_if: the new selected primary_if
+ * @oldif: the old primary interface, may be NULL
+ *
+ * Update the backbone gateways when the own orig address changes.
+ *
+ */
+void bla_update_orig_address(struct bat_priv *bat_priv,
+		struct hard_iface *primary_if, struct hard_iface *oldif)
+{
+	struct backbone_gw *backbone_gw;
+	struct hlist_node *node;
+	struct hlist_head *head;
+	struct hashtable_t *hash;
+	int i;
+
+	if (!oldif) {
+		bla_purge_claims(bat_priv, NULL, 1);
+		bla_purge_backbone_gw(bat_priv, 1);
+		return;
+	}
+
+	hash = bat_priv->backbone_hash;
+	if (!hash)
+		return;
+
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+
+		rcu_read_lock();
+		hlist_for_each_entry_rcu(backbone_gw, node, head, hash_entry) {
+			/* own orig still holds the old value. */
+			if (!compare_eth(backbone_gw->orig,
+					oldif->net_dev->dev_addr))
+				continue;
+
+			memcpy(backbone_gw->orig,
+				primary_if->net_dev->dev_addr, ETH_ALEN);
+			/* send an announce frame so others will ask for our
+			 * claims and update their tables. */
+			bla_send_announce(bat_priv, backbone_gw);
+		}
+		rcu_read_unlock();
+	}
+}
+
+
+
+/* (re)start the timer */
+static void bla_start_timer(struct bat_priv *bat_priv)
+{
+	INIT_DELAYED_WORK(&bat_priv->bla_work, bla_periodic_work);
+	queue_delayed_work(bat_event_workqueue, &bat_priv->bla_work,
+			   msecs_to_jiffies(BLA_PERIOD_LENGTH));
+}
+
+/*
+ * periodic work to do:
+ *  * purge structures when they are too old
+ *  * send announcements
+ */
+
+static void bla_periodic_work(struct work_struct *work)
+{
+	struct delayed_work *delayed_work =
+		container_of(work, struct delayed_work, work);
+	struct bat_priv *bat_priv =
+		container_of(delayed_work, struct bat_priv, bla_work);
+	struct hlist_node *node;
+	struct hlist_head *head;
+	struct backbone_gw *backbone_gw;
+	struct hashtable_t *hash;
+	struct hard_iface *primary_if;
+	int i;
+
+	primary_if = primary_if_get_selected(bat_priv);
+	if (!primary_if)
+		goto out;
+
+	bla_purge_claims(bat_priv, primary_if, 0);
+	bla_purge_backbone_gw(bat_priv, 0);
+
+	if (!atomic_read(&bat_priv->bridge_loop_avoidance))
+		goto out;
+
+	hash = bat_priv->backbone_hash;
+	if (!hash)
+		goto out;
+
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+
+		rcu_read_lock();
+		hlist_for_each_entry_rcu(backbone_gw, node, head, hash_entry) {
+			if (!compare_eth(backbone_gw->orig,
+					primary_if->net_dev->dev_addr))
+				continue;
+
+			backbone_gw->lasttime = jiffies;
+
+			bla_send_announce(bat_priv, backbone_gw);
+		}
+		rcu_read_unlock();
+	}
+out:
+	if (primary_if)
+		hardif_free_ref(primary_if);
+
+	bla_start_timer(bat_priv);
+}
+
+/* initialize all bla structures */
+int bla_init(struct bat_priv *bat_priv)
+{
+	bat_dbg(DBG_BLA, bat_priv, "bla hash registering\n");
+
+	if (bat_priv->claim_hash)
+		return 1;
+
+	bat_priv->claim_hash = hash_new(128);
+	bat_priv->backbone_hash = hash_new(32);
+
+	if (!bat_priv->claim_hash || !bat_priv->backbone_hash)
+		return -1;
+
+	bat_dbg(DBG_BLA, bat_priv, "bla hashes initialized\n");
+
+	bla_start_timer(bat_priv);
+	return 1;
+}
+
+/**
+ * @skb: the frame to be checked
+ * @orig_node: the orig_node of the frame
+ * @hdr_size: maximum length of the frame
+ *
+ * bla_is_backbone_gw inspects the skb for the VLAN ID and returns 1
+ * if the orig_node is also a gateway on the soft interface, otherwise it
+ * returns 0.
+ *
+ **/
+
+int bla_is_backbone_gw(struct sk_buff *skb,
+		struct orig_node *orig_node, int hdr_size)
+{
+	struct ethhdr *ethhdr;
+	struct vlan_ethhdr *vhdr;
+	struct backbone_gw *backbone_gw;
+	short vid = -1;
+
+	if (!atomic_read(&orig_node->bat_priv->bridge_loop_avoidance))
+		return 0;
+
+	/* first, find out the vid. */
+	if (!pskb_may_pull(skb, hdr_size + sizeof(struct ethhdr)))
+		return 0;
+
+	ethhdr = (struct ethhdr *) (((uint8_t *)skb->data) + hdr_size);
+
+	if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
+		if (!pskb_may_pull(skb, hdr_size + sizeof(struct vlan_ethhdr)))
+			return 0;
+
+		vhdr = (struct vlan_ethhdr *) ethhdr;
+		vid = ntohs(vhdr->h_vlan_TCI) & VLAN_VID_MASK;
+	}
+
+	/* see if this originator is a backbone gw for this VLAN */
+
+	backbone_gw = backbone_hash_find(orig_node->bat_priv,
+			orig_node->orig, vid);
+	if (!backbone_gw)
+		return 0;
+
+	bat_dbg(DBG_BLA, orig_node->bat_priv,
+		"bla_is_backbone_gw(): originator %pM has a claim "
+		"for vid %d on the LAN ...\n", orig_node->orig, vid);
+	backbone_gw_free_ref(backbone_gw);
+	return 1;
+}
+
+/* free all bla structures (for softinterface free or module unload) */
+void bla_free(struct bat_priv *bat_priv)
+{
+	struct hard_iface *primary_if;
+
+	cancel_delayed_work_sync(&bat_priv->bla_work);
+	primary_if = primary_if_get_selected(bat_priv);
+
+	if (bat_priv->claim_hash) {
+		bla_purge_claims(bat_priv, primary_if, 1);
+		hash_destroy(bat_priv->claim_hash);
+		bat_priv->claim_hash = NULL;
+	}
+	if (bat_priv->backbone_hash) {
+		bla_purge_backbone_gw(bat_priv, 1);
+		hash_destroy(bat_priv->backbone_hash);
+		bat_priv->backbone_hash = NULL;
+	}
+	if (primary_if)
+		hardif_free_ref(primary_if);
+}
+
+/**
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the frame to be checked
+ * @vid: the VLAN ID of the frame
+ *
+ * bla_rx avoidance checks if:
+ *  * we have to race for a claim
+ *  * if the frame is allowed on the LAN
+ *
+ * in these cases, the skb is further handled by this function and
+ * returns 1, otherwise it returns 0 and the caller shall further
+ * process the skb.
+ *
+ **/
+
+int bla_rx(struct bat_priv *bat_priv, struct sk_buff *skb, short vid)
+{
+	struct ethhdr *ethhdr;
+	struct claim search_claim, *claim = NULL;
+	struct hard_iface *primary_if;
+	int ret;
+
+	ethhdr = (struct ethhdr *)skb_mac_header(skb);
+
+	primary_if = primary_if_get_selected(bat_priv);
+	if (!primary_if)
+		goto handled;
+
+	if (!atomic_read(&bat_priv->bridge_loop_avoidance))
+		goto allow;
+
+
+	if (unlikely(atomic_read(&bat_priv->bla_num_requests)))
+		/* don't allow broadcasts while requests are in flight */
+		if (is_multicast_ether_addr(ethhdr->h_dest))
+			goto handled;
+
+	memcpy(search_claim.addr, ethhdr->h_source, ETH_ALEN);
+	search_claim.vid = vid;
+	claim = claim_hash_find(bat_priv, &search_claim);
+
+	if (!claim) {
+		/* possible optimization: race for a claim */
+		/* No claim exists yet, claim it for us! */
+		handle_claim(bat_priv, primary_if,
+				primary_if->net_dev->dev_addr,
+				ethhdr->h_source, vid);
+		goto allow;
+	}
+
+	/* if it is our own claim ... */
+	if (compare_eth(claim->backbone_gw->orig,
+				primary_if->net_dev->dev_addr)) {
+		/* ... allow it in any case */
+		claim->lasttime = jiffies;
+		goto allow;
+	}
+
+	/* if it is a broadcast ... */
+	if (is_multicast_ether_addr(ethhdr->h_dest)) {
+		/* ... drop it. the responsible gateway is in charge. */
+		goto handled;
+	} else {
+		/* seems the client considers us as its best gateway.
+		 * send a claim and update the claim table
+		 * immediately. */
+		handle_claim(bat_priv, primary_if,
+				primary_if->net_dev->dev_addr,
+				ethhdr->h_source, vid);
+		goto allow;
+	}
+allow:
+	bla_update_own_backbone_gw(bat_priv, primary_if, vid);
+	ret = 0;
+	goto out;
+
+handled:
+	kfree_skb(skb);
+	ret = 1;
+
+out:
+	if (primary_if)
+		hardif_free_ref(primary_if);
+	if (claim)
+		claim_free_ref(claim);
+	return ret;
+}
+
+/**
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the frame to be checked
+ * @vid: the VLAN ID of the frame
+ *
+ * bla_tx checks if:
+ *  * a claim was received which has to be processed
+ *  * the frame is allowed on the mesh
+ *
+ * in these cases, the skb is further handled by this function and
+ * returns 1, otherwise it returns 0 and the caller shall further
+ * process the skb.
+ *
+ **/
+
+int bla_tx(struct bat_priv *bat_priv, struct sk_buff *skb, short vid)
+{
+	struct ethhdr *ethhdr;
+	struct claim search_claim, *claim = NULL;
+	struct hard_iface *primary_if;
+	int ret = 0;
+
+	primary_if = primary_if_get_selected(bat_priv);
+	if (!primary_if)
+		goto out;
+
+	if (!atomic_read(&bat_priv->bridge_loop_avoidance))
+		goto allow;
+
+	/* in VLAN case, the mac header might not be set. */
+	skb_reset_mac_header(skb);
+
+	if (bla_process_claim(bat_priv, primary_if, skb))
+		goto handled;
+
+	ethhdr = (struct ethhdr *)skb_mac_header(skb);
+
+	if (unlikely(atomic_read(&bat_priv->bla_num_requests)))
+		/* don't allow broadcasts while requests are in flight */
+		if (is_multicast_ether_addr(ethhdr->h_dest))
+			goto handled;
+
+	memcpy(search_claim.addr, ethhdr->h_source, ETH_ALEN);
+	search_claim.vid = vid;
+
+	bat_dbg(DBG_BLA, bat_priv,
+		"bla_tx(): checked for claims, now starting ..."
+		"%pM -> %pM [%04x], vid %d\n",
+		ethhdr->h_source, ethhdr->h_dest,
+		ntohs(ethhdr->h_proto), search_claim.vid);
+	claim = claim_hash_find(bat_priv, &search_claim);
+
+	/* if no claim exists, allow it. */
+	if (!claim)
+		goto allow;
+
+	/* check if we are responsible. */
+	if (compare_eth(claim->backbone_gw->orig,
+				primary_if->net_dev->dev_addr)) {
+		/* if yes, the client has roamed and we have
+		 * to unclaim it. */
+		handle_unclaim(bat_priv, primary_if,
+				primary_if->net_dev->dev_addr,
+				ethhdr->h_source, vid);
+		goto allow;
+	}
+
+	/* check if it is a multicast/broadcast frame */
+	if (is_multicast_ether_addr(ethhdr->h_dest)) {
+		/* drop it. the responsible gateway has forwarded it into
+		 * the backbone network. */
+		goto handled;
+	} else {
+		/* we must allow it. at least if we are
+		 * responsible for the DESTINATION. */
+		goto allow;
+	}
+allow:
+	bla_update_own_backbone_gw(bat_priv, primary_if, vid);
+	ret = 0;
+	goto out;
+handled:
+	ret = 1;
+out:
+	if (primary_if)
+		hardif_free_ref(primary_if);
+	if (claim)
+		claim_free_ref(claim);
+	return ret;
+}
diff --git a/bridge_loop_avoidance.h b/bridge_loop_avoidance.h
new file mode 100644
index 0000000..e26848f
--- /dev/null
+++ b/bridge_loop_avoidance.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2011 B.A.T.M.A.N. contributors:
+ *
+ * Simon Wunderlich
+ *
+ * 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
+ *
+ */
+
+int bla_rx(struct bat_priv *bat_priv, struct sk_buff *skb, short vid);
+int bla_tx(struct bat_priv *bat_priv, struct sk_buff *skb, short vid);
+int bla_is_backbone_gw(struct sk_buff *skb,
+		struct orig_node *orig_node, int hdr_size);
+void bla_update_orig_address(struct bat_priv *bat_priv,
+		struct hard_iface *primary_if, struct hard_iface *oldif);
+int bla_init(struct bat_priv *bat_priv);
+void bla_free(struct bat_priv *bat_priv);
+
+#define BLA_CRC_INIT	0
diff --git a/compat.c b/compat.c
index de452e6..304ed6a 100644
--- a/compat.c
+++ b/compat.c
@@ -31,4 +31,12 @@ void free_rcu_tt_local_entry(struct rcu_head *rcu)
 	kfree(tt_local_entry);
 }
 
+void free_rcu_backbone_gw(struct rcu_head *rcu)
+{
+	struct backbone_gw *backbone_gw;
+
+	backbone_gw = container_of(rcu, struct backbone_gw, rcu);
+	kfree(backbone_gw);
+}
+
 #endif /* < KERNEL_VERSION(3, 0, 0) */
diff --git a/compat.h b/compat.h
index 531ba85..41655a6 100644
--- a/compat.h
+++ b/compat.h
@@ -65,10 +65,12 @@
 #if LINUX_VERSION_CODE < KERNEL_VERSION(3, 0, 0)
 
 #define kfree_rcu(ptr, rcu_head) call_rcu(&ptr->rcu_head, free_rcu_##ptr)
+#define vlan_insert_tag(skb, vid) __vlan_put_tag(skb, vid)
 
 void free_rcu_gw_node(struct rcu_head *rcu);
 void free_rcu_neigh_node(struct rcu_head *rcu);
 void free_rcu_tt_local_entry(struct rcu_head *rcu);
+void free_rcu_backbone_gw(struct rcu_head *rcu);
 
 #endif /* < KERNEL_VERSION(3, 0, 0) */
 
diff --git a/hard-interface.c b/hard-interface.c
index 7704df4..2b24d9f 100644
--- a/hard-interface.c
+++ b/hard-interface.c
@@ -29,6 +29,7 @@
 #include "originator.h"
 #include "hash.h"
 #include "bat_ogm.h"
+#include "bridge_loop_avoidance.h"
 
 #include <linux/if_arp.h>
 
@@ -108,7 +109,8 @@ out:
 	return hard_iface;
 }
 
-static void primary_if_update_addr(struct bat_priv *bat_priv)
+static void primary_if_update_addr(struct bat_priv *bat_priv,
+		struct hard_iface *oldif)
 {
 	struct vis_packet *vis_packet;
 	struct hard_iface *primary_if;
@@ -123,6 +125,7 @@ static void primary_if_update_addr(struct bat_priv *bat_priv)
 	memcpy(vis_packet->sender_orig,
 	       primary_if->net_dev->dev_addr, ETH_ALEN);
 
+	bla_update_orig_address(bat_priv, primary_if, oldif);
 out:
 	if (primary_if)
 		hardif_free_ref(primary_if);
@@ -141,14 +144,15 @@ static void primary_if_select(struct bat_priv *bat_priv,
 	curr_hard_iface = rcu_dereference_protected(bat_priv->primary_if, 1);
 	rcu_assign_pointer(bat_priv->primary_if, new_hard_iface);
 
-	if (curr_hard_iface)
-		hardif_free_ref(curr_hard_iface);
-
 	if (!new_hard_iface)
-		return;
+		goto out;
 
 	bat_ogm_init_primary(new_hard_iface);
-	primary_if_update_addr(bat_priv);
+	primary_if_update_addr(bat_priv, curr_hard_iface);
+
+out:
+	if (curr_hard_iface)
+		hardif_free_ref(curr_hard_iface);
 }
 
 static bool hardif_is_iface_up(const struct hard_iface *hard_iface)
@@ -535,7 +539,7 @@ static int hard_if_event(struct notifier_block *this,
 			goto hardif_put;
 
 		if (hard_iface == primary_if)
-			primary_if_update_addr(bat_priv);
+			primary_if_update_addr(bat_priv, NULL);
 		break;
 	default:
 		break;
diff --git a/main.c b/main.c
index 36661b4..85cb79b 100644
--- a/main.c
+++ b/main.c
@@ -30,6 +30,7 @@
 #include "translation-table.h"
 #include "hard-interface.h"
 #include "gateway_client.h"
+#include "bridge_loop_avoidance.h"
 #include "vis.h"
 #include "hash.h"
 
@@ -109,6 +110,9 @@ int mesh_init(struct net_device *soft_iface)
 	if (vis_init(bat_priv) < 1)
 		goto err;
 
+	if (bla_init(bat_priv) < 1)
+		goto err;
+
 	atomic_set(&bat_priv->gw_reselect, 0);
 	atomic_set(&bat_priv->mesh_state, MESH_ACTIVE);
 	goto end;
@@ -136,6 +140,8 @@ void mesh_free(struct net_device *soft_iface)
 
 	tt_free(bat_priv);
 
+	bla_free(bat_priv);
+
 	atomic_set(&bat_priv->mesh_state, MESH_INACTIVE);
 }
 
diff --git a/main.h b/main.h
index b395c7b..1bd41f1 100644
--- a/main.h
+++ b/main.h
@@ -79,6 +79,9 @@
 #define MAX_AGGREGATION_BYTES 512
 #define MAX_AGGREGATION_MS 100
 
+#define BLA_PERIOD_LENGTH	10000	/* 10 seconds */
+#define BLA_BACKBONE_TIMEOUT	(BLA_PERIOD_LENGTH * 3)
+#define BLA_CLAIM_TIMEOUT	(BLA_PERIOD_LENGTH * 10)
 /* don't reset again within 30 seconds */
 #define RESET_PROTECTION_MS 30000
 #define EXPECTED_SEQNO_RANGE	65536
@@ -118,7 +121,8 @@ enum dbg_level {
 	DBG_BATMAN = 1 << 0,
 	DBG_ROUTES = 1 << 1, /* route added / changed / deleted */
 	DBG_TT	   = 1 << 2, /* translation table operations */
-	DBG_ALL    = 7
+	DBG_BLA    = 1 << 3, /* bridge loop avoidance */
+	DBG_ALL    = 15
 };
 
 
diff --git a/originator.c b/originator.c
index a9c8b66..52e778a 100644
--- a/originator.c
+++ b/originator.c
@@ -28,6 +28,7 @@
 #include "hard-interface.h"
 #include "unicast.h"
 #include "soft-interface.h"
+#include "bridge_loop_avoidance.h"
 
 static void purge_orig(struct work_struct *work);
 
diff --git a/packet.h b/packet.h
index 4d9e54c..48c7b74 100644
--- a/packet.h
+++ b/packet.h
@@ -90,6 +90,22 @@ enum tt_client_flags {
 	TT_CLIENT_PENDING = 1 << 10
 };
 
+/* claim frame types for the bridge loop avoidance */
+enum bla_claimframe {
+	CLAIM_TYPE_ADD		= 0x00,
+	CLAIM_TYPE_DEL		= 0x01,
+	CLAIM_TYPE_ANNOUNCE	= 0x02,
+	CLAIM_TYPE_REQUEST	= 0x03
+};
+
+/* the destination hardware field in the ARP frame is used to
+ * transport the claim type and the group id */
+struct bla_claim_dst {
+	uint8_t magic[3];	/* FF:43:05 */
+	uint8_t type;		/* bla_claimframe */
+	uint16_t group;		/* group id */
+} __packed;
+
 struct batman_ogm_packet {
 	uint8_t  packet_type;
 	uint8_t  version;  /* batman version field */
diff --git a/routing.c b/routing.c
index ef24a72..8050fb2 100644
--- a/routing.c
+++ b/routing.c
@@ -30,6 +30,7 @@
 #include "vis.h"
 #include "unicast.h"
 #include "bat_ogm.h"
+#include "bridge_loop_avoidance.h"
 
 void slide_own_bcast_window(struct hard_iface *hard_iface)
 {
@@ -1074,6 +1075,11 @@ int recv_bcast_packet(struct sk_buff *skb, struct hard_iface *recv_if)
 	/* rebroadcast packet */
 	add_bcast_packet_to_list(bat_priv, skb, 1);
 
+	/* don't hand the broadcast up if it is from an originator
+	 * from the same backbone. */
+	if (bla_is_backbone_gw(skb, orig_node, hdr_size))
+		goto out;
+
 	/* broadcast for me */
 	interface_rx(recv_if->soft_iface, skb, recv_if, hdr_size);
 	ret = NET_RX_SUCCESS;
diff --git a/soft-interface.c b/soft-interface.c
index 4806deb..46dd328 100644
--- a/soft-interface.c
+++ b/soft-interface.c
@@ -36,6 +36,7 @@
 #include <linux/etherdevice.h>
 #include <linux/if_vlan.h>
 #include "unicast.h"
+#include "bridge_loop_avoidance.h"
 
 
 static int bat_get_settings(struct net_device *dev, struct ethtool_cmd *cmd);
@@ -151,6 +152,9 @@ static int interface_tx(struct sk_buff *skb, struct net_device *soft_iface)
 		goto dropped;
 	}
 
+	if (bla_tx(bat_priv, skb, vid))
+		goto dropped;
+
 	/* Register the client MAC in the transtable */
 	tt_local_add(soft_iface, ethhdr->h_source, skb->skb_iif);
 
@@ -286,6 +290,11 @@ void interface_rx(struct net_device *soft_iface,
 	if (is_ap_isolated(bat_priv, ethhdr->h_source, ethhdr->h_dest))
 		goto dropped;
 
+	/* Let the bridge loop avoidance check the packet. If will
+	 * not handle it, we can safely push it up. */
+	if (bla_rx(bat_priv, skb, vid))
+		goto out;
+
 	netif_rx(skb);
 	goto out;
 
@@ -355,6 +364,7 @@ struct net_device *softif_create(const char *name)
 
 	atomic_set(&bat_priv->aggregated_ogms, 1);
 	atomic_set(&bat_priv->bonding, 0);
+	atomic_set(&bat_priv->bridge_loop_avoidance, 1);
 	atomic_set(&bat_priv->ap_isolation, 0);
 	atomic_set(&bat_priv->vis_mode, VIS_TYPE_CLIENT_UPDATE);
 	atomic_set(&bat_priv->gw_mode, GW_MODE_OFF);
@@ -372,6 +382,7 @@ struct net_device *softif_create(const char *name)
 	atomic_set(&bat_priv->ttvn, 0);
 	atomic_set(&bat_priv->tt_local_changes, 0);
 	atomic_set(&bat_priv->tt_ogm_append_cnt, 0);
+	atomic_set(&bat_priv->bla_num_requests, 0);
 
 	bat_priv->tt_buff = NULL;
 	bat_priv->tt_buff_len = 0;
diff --git a/types.h b/types.h
index d1139b9..69984c9 100644
--- a/types.h
+++ b/types.h
@@ -147,6 +147,7 @@ struct bat_priv {
 	atomic_t bonding;		/* boolean */
 	atomic_t fragmentation;		/* boolean */
 	atomic_t ap_isolation;		/* boolean */
+	atomic_t bridge_loop_avoidance;	/* boolean */
 	atomic_t vis_mode;		/* VIS_TYPE_* */
 	atomic_t gw_mode;		/* GW_MODE_* */
 	atomic_t gw_sel_class;		/* uint */
@@ -160,6 +161,7 @@ struct bat_priv {
 	atomic_t ttvn; /* translation table version number */
 	atomic_t tt_ogm_append_cnt;
 	atomic_t tt_local_changes; /* changes registered in a OGM interval */
+	atomic_t bla_num_requests; /* number of bla requests in flight */
 	/* The tt_poss_change flag is used to detect an ongoing roaming phase.
 	 * If true, then I received a Roaming_adv and I have to inspect every
 	 * packet directed to me to check whether I am still the true
@@ -178,6 +180,8 @@ struct bat_priv {
 	struct hashtable_t *orig_hash;
 	struct hashtable_t *tt_local_hash;
 	struct hashtable_t *tt_global_hash;
+	struct hashtable_t *claim_hash;
+	struct hashtable_t *backbone_hash;
 	struct list_head tt_req_list; /* list of pending tt_requests */
 	struct list_head tt_roam_list;
 	struct hashtable_t *vis_hash;
@@ -198,6 +202,7 @@ struct bat_priv {
 	struct delayed_work tt_work;
 	struct delayed_work orig_work;
 	struct delayed_work vis_work;
+	struct delayed_work bla_work;
 	struct gw_node __rcu *curr_gw;  /* rcu protected pointer */
 	atomic_t gw_reselect;
 	struct hard_iface __rcu *primary_if;  /* rcu protected pointer */
@@ -239,6 +244,28 @@ struct tt_global_entry {
 	unsigned long roam_at; /* time at which TT_GLOBAL_ROAM was set */
 };
 
+struct backbone_gw {
+	uint8_t orig[ETH_ALEN];
+	short vid;		/* used VLAN ID */
+	struct hlist_node hash_entry;
+	struct bat_priv *bat_priv;
+	unsigned long lasttime;	/* last time we heard of this backbone gw */
+	atomic_t request_sent;
+	atomic_t refcount;
+	struct rcu_head rcu;
+	uint16_t crc;		/* crc checksum over all claims */
+};
+
+struct claim {
+	uint8_t addr[ETH_ALEN];
+	short vid;
+	struct backbone_gw *backbone_gw;
+	unsigned long lasttime;	/* last time we heard of claim (locals only) */
+	struct rcu_head rcu;
+	atomic_t refcount;
+	struct hlist_node hash_entry;
+};
+
 struct tt_change_node {
 	struct list_head list;
 	struct tt_change change;
