From a73105b8d4c765d9ebfb664d0a66802127d8e4c7 Mon Sep 17 00:00:00 2001 From: Antonio Quartulli Date: Wed, 27 Apr 2011 14:27:44 +0200 Subject: batman-adv: improved client announcement mechanism The client announcement mechanism informs every mesh node in the network of any connected non-mesh client, in order to find the path towards that client from any given point in the mesh. The old implementation was based on the simple idea of appending a data buffer to each OGM containing all the client MAC addresses the node is serving. All other nodes can populate their global translation tables (table which links client MAC addresses to node addresses) using this MAC address buffer and linking it to the node's address contained in the OGM. A node that wants to contact a client has to lookup the node the client is connected to and its address in the global translation table. It is easy to understand that this implementation suffers from several issues: - big overhead (each and every OGM contains the entire list of connected clients) - high latencies for client route updates due to long OGM trip time and OGM losses The new implementation addresses these issues by appending client changes (new client joined or a client left) to the OGM instead of filling it with all the client addresses each time. In this way nodes can modify their global tables by means of "updates", thus reducing the overhead within the OGMs. To keep the entire network in sync each node maintains a translation table version number (ttvn) and a translation table checksum. These values are spread with the OGM to allow all the network participants to determine whether or not they need to update their translation table information. When a translation table lookup is performed in order to send a packet to a client attached to another node, the destination's ttvn is added to the payload packet. Forwarding nodes can compare the packet's ttvn with their destination's ttvn (this node could have a fresher information than the source) and re-route the packet if necessary. This greatly reduces the packet loss of clients roaming from one AP to the next. Signed-off-by: Antonio Quartulli Signed-off-by: Marek Lindner Signed-off-by: Sven Eckelmann --- net/batman-adv/soft-interface.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'net/batman-adv/soft-interface.c') diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c index 69c002279e63..c288d937a154 100644 --- a/net/batman-adv/soft-interface.c +++ b/net/batman-adv/soft-interface.c @@ -534,7 +534,7 @@ static int interface_set_mac_addr(struct net_device *dev, void *p) /* only modify transtable if it has been initialised before */ if (atomic_read(&bat_priv->mesh_state) == MESH_ACTIVE) { tt_local_remove(bat_priv, dev->dev_addr, - "mac address changed"); + "mac address changed"); tt_local_add(dev, addr->sa_data); } @@ -592,7 +592,7 @@ static int interface_tx(struct sk_buff *skb, struct net_device *soft_iface) if (curr_softif_neigh) goto dropped; - /* TODO: check this for locks */ + /* Register the client MAC in the transtable */ tt_local_add(soft_iface, ethhdr->h_source); if (is_multicast_ether_addr(ethhdr->h_dest)) { @@ -830,7 +830,12 @@ struct net_device *softif_create(const char *name) atomic_set(&bat_priv->mesh_state, MESH_INACTIVE); atomic_set(&bat_priv->bcast_seqno, 1); - atomic_set(&bat_priv->tt_local_changed, 0); + atomic_set(&bat_priv->ttvn, 0); + atomic_set(&bat_priv->tt_local_changes, 0); + atomic_set(&bat_priv->tt_ogm_append_cnt, 0); + + bat_priv->tt_buff = NULL; + bat_priv->tt_buff_len = 0; bat_priv->primary_if = NULL; bat_priv->num_ifaces = 0; -- cgit v1.2.3