[state: 27-01-2011] 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/ # aggregated_ogms gw_bandwidth hop_penalty # bonding gw_mode orig_interval # fragmentation gw_sel_class vis_mode There is a special folder for debugging informations: # ls /sys/kernel/debug/batman_adv/bat0/ # gateways socket transtable_global vis_data # originators softif_neigh transtable_local 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: 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/kernel/debug/batman_adv/bat0/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". 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 route or hna added / changed / deleted 3 - Enable all messages The debug output can be changed at runtime using the file /sys/class/net/bat0/mesh/log_level. e.g. # echo 2 > /sys/class/net/bat0/mesh/log_level will enable debug messages for when routes or HNAs change. 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.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 Simon Wunderlich