linux-next/drivers/staging/batman-adv

[state: 03-05-2010]

BATMAN-ADV
----------

Batman  advanced  is  a new approach to wireless networking which
does no longer operate on the IP basis. Unlike the batman daemon,
which  exchanges  information  using UDP packets and sets routing
tables, batman-advanced operates on ISO/OSI Layer 2 only and uses
and  routes  (or  better: bridges) Ethernet Frames. It emulates a
virtual network switch of all nodes participating.  Therefore all
nodes  appear  to be link local, thus all higher operating proto-
cols won't be affected by any changes within the network. You can
run almost any protocol above batman advanced, prominent examples
are: IPv4, IPv6, DHCP, IPX.

Batman advanced was implemented as a Linux kernel driver  to  re-
duce the overhead to a minimum. It does not depend on any (other)
network driver, and can be used on wifi as well as ethernet  lan,
vpn,  etc ... (anything with ethernet-style layer 2).

CONFIGURATION
-------------

Load the batman-adv module into your kernel:

# insmod batman-adv.ko

The  module  is now waiting for activation. You must add some in-
terfaces on which batman can operate. After  loading  the  module
batman  advanced  will scan your systems interfaces to search for
compatible interfaces. Once found, it will create  subfolders  in
the /sys directories of each supported interface, e.g.

# ls /sys/class/net/eth0/batman_adv/
# iface_status  mesh_iface

If an interface does not have the "batman_adv" subfolder it prob-
ably is not supported. Not supported  interfaces  are:  loopback,
non-ethernet and batman's own interfaces.

Note:  After the module was loaded it will continuously watch for
new interfaces to verify the compatibility. There is no  need  to
reload the module if you plug your USB wifi adapter into your ma-
chine after batman advanced was initially loaded.

To activate a  given  interface  simply  write  "bat0"  into  its
"mesh_iface" file inside the batman_adv subfolder:

# echo bat0 > /sys/class/net/eth0/batman_adv/mesh_iface

Repeat  this step for all interfaces you wish to add.  Now batman
starts using/broadcasting on this/these interface(s).

By reading the "iface_status" file you can check its status:

# cat /sys/class/net/eth0/batman_adv/iface_status
# active

To deactivate an interface you have  to  write  "none"  into  its
"mesh_iface" file:

# echo none > /sys/class/net/eth0/batman_adv/mesh_iface


All  mesh  wide  settings  can be found in batman's own interface
folder:

#  ls  /sys/class/net/bat0/mesh/
#  aggregate_ogm   originators        transtable_global  vis_mode
#  orig_interval   transtable_local   vis_data


Some of the files contain all sort of status information  regard-
ing  the  mesh  network.  For  example, you can view the table of
originators (mesh participants) with:

# cat /sys/class/net/bat0/mesh/originators

Other files allow to change batman's behaviour to better fit your
requirements.  For instance, you can check the current originator
interval (value in milliseconds which determines how often batman
sends its broadcast packets):

# cat /sys/class/net/bat0/mesh/orig_interval
# status: 1000

and also change its value:

# echo 3000 > /sys/class/net/bat0/mesh/orig_interval

In very mobile scenarios, you might want to adjust the originator
interval to a lower value. This will make the mesh  more  respon-
sive to topology changes, but will also increase the overhead.


USAGE
-----

To  make use of your newly created mesh, batman advanced provides
a new interface "bat0" which you should use from this  point  on.
All  interfaces  added  to  batman  advanced are not relevant any
longer because batman handles them for you. Basically, one "hands
over" the data by using the batman interface and batman will make
sure it reaches its destination.

The "bat0" interface can be used like any  other  regular  inter-
face.  It needs an IP address which can be either statically con-
figured or dynamically (by using DHCP or similar services):

# NodeA: ifconfig bat0 192.168.0.1
# NodeB: ifconfig bat0 192.168.0.2
# NodeB: ping 192.168.0.1

Note:  In  order to avoid problems remove all IP addresses previ-
ously assigned to interfaces now used by batman advanced, e.g.

# ifconfig eth0 0.0.0.0


VISUALIZATION
-------------

If you want topology visualization, at least one mesh  node  must
be configured as VIS-server:

# echo "server" > /sys/class/net/bat0/mesh/vis_mode

Each  node  is  either configured as "server" or as "client" (de-
fault: "client").  Clients send their topology data to the server
next to them, and server synchronize with other servers. If there
is no server configured (default) within the  mesh,  no  topology
information   will  be  transmitted.  With  these  "synchronizing
servers", there can be 1 or more vis servers sharing the same (or
at least very similar) data.

When  configured  as  server,  you can get a topology snapshot of
your mesh:

# cat /sys/class/net/bat0/mesh/vis_data

This raw output is intended to be easily parsable and convertable
with  other tools. Have a look at the batctl README if you want a
vis output in dot or json format for instance and how those  out-
puts could then be visualised in an image.

The raw format consists of comma separated values per entry where
each entry is giving information about a  certain  source  inter-
face.  Each  entry can/has to have the following values:
-> "mac" - mac address of an originator's source interface
           (each line begins with it)
-> "TQ mac  value"  -  src mac's link quality towards mac address
                       of a neighbor originator's interface which
                       is being used for routing
-> "HNA mac" - HNA announced by source mac
-> "PRIMARY" - this  is a primary interface
-> "SEC mac" - secondary mac address of source
               (requires preceding PRIMARY)

The TQ value has a range from 4 to 255 with 255 being  the  best.
The HNA entries are showing which hosts are connected to the mesh
via bat0 or being bridged into the mesh network.  The PRIMARY/SEC
values are only applied on primary interfaces


LOGGING/DEBUGGING
-----------------

All error messages, warnings and information messages are sent to
the kernel log. Depending on your operating  system  distribution
this  can  be read in one of a number of ways. Try using the com-
mands: dmesg, logread, or looking in the files  /var/log/kern.log
or  /var/log/syslog.  All  batman-adv  messages are prefixed with
"batman-adv:" So to see just these messages try

# dmesg | grep batman-adv

When investigating problems with your mesh network  it  is  some-
times  necessary  to see more detail debug messages. This must be
enabled when compiling the batman-adv module. When building  bat-
man-adv  as  part of kernel, use "make menuconfig" and enable the
option "B.A.T.M.A.N. debugging".

The additional debug output is by default disabled. It can be en-
abled  either  at kernel modules load time or during run time. To
enable debug output at module load time, add the module parameter
debug=<value>.  <value> can take one of four values.

0 - All  debug  output  disabled
1 - Enable messages related to routing / flooding / broadcasting
2 - Enable route or hna added / changed / deleted
3 - Enable all messages

e.g.

# modprobe batman-adv debug=2

will load the module and enable debug messages for when routes or
HNAs change.

The debug output can also be changed at runtime  using  the  file
/sys/module/batman-adv/parameters/debug. e.g.

# echo 2 > /sys/module/batman-adv/parameters/debug

enables debug messages for when routes or HNAs

The  debug  output  is sent to the kernel logs. So try dmesg, lo-
gread, etc to see the debug messages.


BATCTL
------

As batman advanced operates on layer 2 all hosts participating in
the  virtual switch are completely transparent for all  protocols
above layer 2. Therefore the common diagnosis tools do  not  work
as  expected.  To  overcome these problems batctl was created. At
the  moment the  batctl contains ping,  traceroute,  tcpdump  and
interfaces to the kernel module settings.

For more information, please see the manpage (man batctl).

batctl is available on http://www.open-mesh.org/


CONTACT
-------

Please send us comments, experiences, questions, anything :)

IRC:            #batman   on   irc.freenode.org
Mailing-list:   b.a.t.m.a.n@open-mesh.net (optional  subscription
          at https://lists.open-mesh.org/mm/listinfo/b.a.t.m.a.n)

You can also contact the Authors:

Marek  Lindner  <lindner_marek@yahoo.de>
Simon  Wunderlich  <siwu@hrz.tu-chemnitz.de>