In case of wireless interface retrieve the throughput by
querying cfg80211. To perform this call a separate work
must be scheduled because the function may sleep and this
is not allowed within an RCU protected context (RCU in this
case is used to iterate over all the neighbours).
Use ethtool to retrieve information about an Ethernet link
like HALF/FULL_DUPLEX and advertised bandwidth (e.g.
100/10Mbps).
The metric is updated each time a new ELP packet is sent,
this way it is possible to timely react to a metric
variation which can imply (for example) a neighbour
disconnection.
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Initially developed by Linus during a 6 months trainee study
period in Ascom (Switzerland) AG.
Signed-off-by: Linus Luessing <linus.luessing@web.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
The B.A.T.M.A.N. protocol originally only used a single
message type (called OGM) to determine the link qualities to
the direct neighbors and spreading these link quality
information through the whole mesh. This procedure is
summarized on the BATMAN concept page and explained in
details in the RFC draft published in 2008.
This approach was chosen for its simplicity during the
protocol design phase and the implementation. However, it
also bears some drawbacks:
* Wireless interfaces usually come with some packet loss,
therefore a higher broadcast rate is desirable to allow
a fast reaction on flaky connections.
Other interfaces of the same host might be connected to
Ethernet LANs / VPNs / etc which rarely exhibit packet
loss would benefit from a lower broadcast rate to reduce
overhead.
* It generally is more desirable to detect local link
quality changes at a faster rate than propagating all
these changes through the entire mesh (the far end of
the mesh does not need to care about local link quality
changes that much). Other optimizations strategies, like
reducing overhead, might be possible if OGMs weren't
used for all tasks in the mesh at the same time.
As a result detecting local link qualities shall be handled
by an independent message type, ELP, whereas the OGM message
type remains responsible for flooding the mesh with these
link quality information and determining the overall path
transmit qualities.
Developed by Linus during a 6 months trainee study period in
Ascom (Switzerland) AG.
Signed-off-by: Linus Luessing <linus.luessing@web.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Antonio Quartulli
Linus Luessing