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diff --git a/Documentation/networking/batman-adv.rst b/Documentation/networking/batman-adv.rst new file mode 100644 index 000000000..245fb6c0a --- /dev/null +++ b/Documentation/networking/batman-adv.rst @@ -0,0 +1,222 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========== +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 protocols 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 reduce 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 interfaces 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 probably 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 machine 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 regarding 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 responsive 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 interface. It needs an +IP address which can be either statically configured 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 previously 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 commands: ``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 sometimes necessary to +see more detail debug messages. This must be enabled when compiling the +batman-adv module. When building batman-adv as part of kernel, use "make +menuconfig" and enable the option ``B.A.T.M.A.N. debugging`` +(``CONFIG_BATMAN_ADV_DEBUG=y``). + +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 enabled during +run time. Following log_levels are defined: + +.. flat-table:: + + * - 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> |