22 Mar, 2014

1 commit


14 Mar, 2013

1 commit

  • Network coding exploits the 802.11 shared medium to allow multiple
    packets to be sent in a single transmission. In brief, a relay can XOR
    two packets, and send the coded packet to two destinations. The
    receivers can decode one of the original packets by XOR'ing the coded
    packet with the other original packet. This will lead to increased
    throughput in topologies where two packets cross one relay.

    In a simple topology with three nodes, it takes four transmissions
    without network coding to get one packet from Node A to Node B and one
    from Node B to Node A:

    1. Node A ---- p1 ---> Node R Node B
    2. Node A Node R Node B

    With network coding, the relay only needs one transmission, which saves
    us one slot of valuable airtime:

    1. Node A ---- p1 ---> Node R Node B
    2. Node A Node R Node B

    The same principle holds for a topology including five nodes. Here the
    packets from Node A and Node B are overheard by Node C and Node D,
    respectively. This allows Node R to send a network coded packet to save
    one transmission:

    Node A Node B

    | \ / |
    | p1 p2 |
    | \ / |
    p1 > Node R < p2
    | |
    | / \ |
    | p1 x p2 p1 x p2 |
    v / \ v
    / \
    Node C < > Node D

    More information is available on the open-mesh.org wiki[1].

    This patch adds the initial code to support network coding in
    batman-adv. It sets up a worker thread to do house keeping and adds a
    sysfs file to enable/disable network coding. The feature is disabled by
    default, as it requires a wifi-driver with working promiscuous mode, and
    also because it adds a small delay at each hop.

    [1] http://www.open-mesh.org/projects/batman-adv/wiki/Catwoman

    Signed-off-by: Martin Hundebøll
    Signed-off-by: Marek Lindner
    Signed-off-by: Antonio Quartulli

    Martin Hundebøll
     

21 Nov, 2012

1 commit


08 Nov, 2012

2 commits


11 Apr, 2012

3 commits

  • The define CONFIG_BATMAN_ADV_BLA switches the bridge loop avoidance
    on - skip it, and the bridge loop avoidance is not compiled in.

    This is useful if binary size should be saved or the feature is
    not needed.

    Signed-off-by: Simon Wunderlich
    Signed-off-by: Antonio Quartulli

    Simon Wunderlich
     
  • This second version of the bridge loop avoidance for batman-adv
    avoids loops between the mesh and a backbone (usually a LAN).

    By connecting multiple batman-adv mesh nodes to the same ethernet
    segment a loop can be created when the soft-interface is bridged
    into that ethernet segment. A simple visualization of the loop
    involving the most common case - a LAN as ethernet segment:

    node1 node2
    | |
    wifi wifi

    Packets from the LAN (e.g. ARP broadcasts) will circle forever from
    node1 or node2 over the mesh back into the LAN.

    With this patch, batman recognizes backbone gateways, nodes which are
    part of the mesh and backbone/LAN at the same time. Each backbone
    gateway "claims" clients from within the mesh to handle them
    exclusively. By restricting that only responsible backbone gateways
    may handle their claimed clients traffic, loops are effectively
    avoided.

    Signed-off-by: Simon Wunderlich
    Signed-off-by: Antonio Quartulli

    Simon Wunderlich
     
  • Signed-off-by: Antonio Quartulli

    Antonio Quartulli
     

20 Jun, 2011

1 commit

  • 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

    Antonio Quartulli
     

17 Dec, 2010

1 commit

  • B.A.T.M.A.N. (better approach to mobile ad-hoc networking) is a routing
    protocol for multi-hop ad-hoc mesh networks. The networks may be wired or
    wireless. See http://www.open-mesh.org/ for more information and user space
    tools.

    Signed-off-by: Sven Eckelmann
    Signed-off-by: David S. Miller

    Sven Eckelmann