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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/
# elp_interval iface_status mesh_iface throughput_override
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.
The batman-adv soft-interface can be created using the iproute2
tool "ip"
# ip link add name bat0 type batadv
To activate a given interface simply attach it to the "bat0"
interface
# ip link set dev eth0 master bat0
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 detach it from the
"bat0" interface:
# ip link set dev eth0 nomaster
All mesh wide settings can be found in batman's own interface
folder:
# ls /sys/class/net/bat0/mesh/
# aggregated_ogms fragmentation isolation_mark routing_algo
# ap_isolation gw_bandwidth log_level vlan0
# bonding gw_mode multicast_mode
# bridge_loop_avoidance gw_sel_class network_coding
# distributed_arp_table hop_penalty orig_interval
There is a special folder for debugging information:
# ls /sys/kernel/debug/batman_adv/bat0/
# bla_backbone_table log neighbors transtable_local
# bla_claim_table mcast_flags originators
# dat_cache nc socket
# gateways nc_nodes transtable_global
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/kernel/debug/batman_adv/bat0/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
# 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: ip link set up dev bat0
# NodeA: ip addr add 192.168.0.1/24 dev bat0
# NodeB: ip link set up dev bat0
# NodeB: ip addr add 192.168.0.2/24 dev bat0
# 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.
# ip addr flush dev eth0
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".
Those additional debug messages can be accessed using a special
file in debugfs
# cat /sys/kernel/debug/batman_adv/bat0/log
The additional debug output is by default disabled. It can be en-
abled during run time. Following log_levels are defined:
0 - All debug output disabled
1 - Enable messages related to routing / flooding / broadcasting
2 - Enable messages related to route added / changed / deleted
4 - Enable messages related to translation table operations
8 - Enable messages related to bridge loop avoidance
16 - Enable messages related to DAT, ARP snooping and parsing
32 - Enable messages related to network coding
64 - Enable messages related to multicast
128 - Enable messages related to throughput meter
255 - Enable all messages
The debug output can be changed at runtime using the file
/sys/class/net/bat0/mesh/log_level. e.g.
# echo 6 > /sys/class/net/bat0/mesh/log_level
will enable debug messages for when routes change.
Counters for different types of packets entering and leaving the
batman-adv module are available through ethtool:
# ethtool --statistics bat0
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 https://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.org (optional subscription
at https://lists.open-mesh.org/mm/listinfo/b.a.t.m.a.n)
You can also contact the Authors:
Marek Lindner <mareklindner@neomailbox.ch>
Simon Wunderlich <sw@simonwunderlich.de>
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