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. 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 distributed_arp_table gw_sel_class orig_interval #ap_isolation fragmentation hop_penalty routing_algo #bonding gw_bandwidth isolation_mark vlan0 #bridge_loop_avoidance gw_mode log_level There is a special folder for debugging information: # ls /sys/kernel/debug/batman_adv/bat0/ # bla_backbone_table log transtable_global # bla_claim_table originators transtable_local # gateways socket 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 messaged related to DAT, ARP snooping and parsing 31 - 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 Simon Wunderlich