[state: 03-05-2010] BATMAN-ADV ---------- Batman advanced is a new approach to wireless networking which no longer operate on the IP level. Unlike the batman daemon, which exchanges information using UDP packets and sets entries in routing tables, batman-advanced operates on ISO/OSI Layer 2. It uses and routes (or better: bridges) Ethernet Frames. It emulates a virtual network switch containing all of the participating nodes. Therefore all nodes appear to be link local to each other. All protocols operating at higher won't be affected by any changes within the mesh network. You can run almost any protocol above batman advanced, prominent examples are: IPv4, IPv6, DHCP and IPX. Batman advanced is implemented as a Linux kernel driver, so reducing the overheads 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). It compiles against and should work with Linux 2.6.20 - 2.6.33. Supporting older versions is not planned, but it's probably easy to backport it. If you work on a backport, feel free to contact us. :-) COMPILE ------- To compile against your currently installed kernel, just type: # make if you want to compile against some other kernel, use: # make KERNELPATH=/path/to/kernel 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 for each supported interface, e.g. # ls /sys/class/net/eth0/batman_adv/ [Might be nice to show the output here] 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 is 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. 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 [Might be nice to show the contents of the file] 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/ [Might be nice to list the files] 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/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 [Might be nice to show the contents of the file] 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: ifconfig bat0 192.168.0.1 up # NodeB: ifconfig bat0 192.168.0.2 up # 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. # 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" (default: "client"). Clients send their topology data to the server next to them, and servers 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 convertible 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 outputs 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 interface. 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 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". When compiling outside of the kernel tree it is necessary to edit the file Makefile.kbuild and uncomment the line #EXTRA_CFLAGS += -DCONFIG_BATMAN_ADV_DEBUG The additional debug output is by default disabled. It can be enabled either at kernel modules load time or during run time. To enable debug output at module load time, add the module parameter debug=. 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 run time 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, logread, 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 Simon Wunderlich