242 lines
8.4 KiB
Plaintext
242 lines
8.4 KiB
Plaintext
[state: 17-04-2011]
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BATMAN-ADV
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----------
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Batman advanced is a new approach to wireless networking which
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does no longer operate on the IP basis. Unlike the batman daemon,
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which exchanges information using UDP packets and sets routing
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tables, batman-advanced operates on ISO/OSI Layer 2 only and uses
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and routes (or better: bridges) Ethernet Frames. It emulates a
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virtual network switch of all nodes participating. Therefore all
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nodes appear to be link local, thus all higher operating proto-
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cols won't be affected by any changes within the network. You can
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run almost any protocol above batman advanced, prominent examples
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are: IPv4, IPv6, DHCP, IPX.
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Batman advanced was implemented as a Linux kernel driver to re-
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duce the overhead to a minimum. It does not depend on any (other)
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network driver, and can be used on wifi as well as ethernet lan,
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vpn, etc ... (anything with ethernet-style layer 2).
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CONFIGURATION
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-------------
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Load the batman-adv module into your kernel:
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# insmod batman-adv.ko
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The module is now waiting for activation. You must add some in-
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terfaces on which batman can operate. After loading the module
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batman advanced will scan your systems interfaces to search for
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compatible interfaces. Once found, it will create subfolders in
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the /sys directories of each supported interface, e.g.
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# ls /sys/class/net/eth0/batman_adv/
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# iface_status mesh_iface
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If an interface does not have the "batman_adv" subfolder it prob-
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ably is not supported. Not supported interfaces are: loopback,
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non-ethernet and batman's own interfaces.
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Note: After the module was loaded it will continuously watch for
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new interfaces to verify the compatibility. There is no need to
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reload the module if you plug your USB wifi adapter into your ma-
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chine after batman advanced was initially loaded.
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To activate a given interface simply write "bat0" into its
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"mesh_iface" file inside the batman_adv subfolder:
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# echo bat0 > /sys/class/net/eth0/batman_adv/mesh_iface
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Repeat this step for all interfaces you wish to add. Now batman
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starts using/broadcasting on this/these interface(s).
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By reading the "iface_status" file you can check its status:
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# cat /sys/class/net/eth0/batman_adv/iface_status
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# active
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To deactivate an interface you have to write "none" into its
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"mesh_iface" file:
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# echo none > /sys/class/net/eth0/batman_adv/mesh_iface
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All mesh wide settings can be found in batman's own interface
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folder:
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# ls /sys/class/net/bat0/mesh/
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# aggregated_ogms gw_bandwidth hop_penalty
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# bonding gw_mode orig_interval
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# fragmentation gw_sel_class vis_mode
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There is a special folder for debugging information:
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# ls /sys/kernel/debug/batman_adv/bat0/
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# gateways socket transtable_global vis_data
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# originators softif_neigh transtable_local
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Some of the files contain all sort of status information regard-
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ing the mesh network. For example, you can view the table of
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originators (mesh participants) with:
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# cat /sys/kernel/debug/batman_adv/bat0/originators
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Other files allow to change batman's behaviour to better fit your
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requirements. For instance, you can check the current originator
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interval (value in milliseconds which determines how often batman
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sends its broadcast packets):
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# cat /sys/class/net/bat0/mesh/orig_interval
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# 1000
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and also change its value:
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# echo 3000 > /sys/class/net/bat0/mesh/orig_interval
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In very mobile scenarios, you might want to adjust the originator
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interval to a lower value. This will make the mesh more respon-
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sive to topology changes, but will also increase the overhead.
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USAGE
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-----
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To make use of your newly created mesh, batman advanced provides
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a new interface "bat0" which you should use from this point on.
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All interfaces added to batman advanced are not relevant any
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longer because batman handles them for you. Basically, one "hands
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over" the data by using the batman interface and batman will make
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sure it reaches its destination.
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The "bat0" interface can be used like any other regular inter-
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face. It needs an IP address which can be either statically con-
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figured or dynamically (by using DHCP or similar services):
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# NodeA: ifconfig bat0 192.168.0.1
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# NodeB: ifconfig bat0 192.168.0.2
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# NodeB: ping 192.168.0.1
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Note: In order to avoid problems remove all IP addresses previ-
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ously assigned to interfaces now used by batman advanced, e.g.
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# ifconfig eth0 0.0.0.0
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VISUALIZATION
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-------------
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If you want topology visualization, at least one mesh node must
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be configured as VIS-server:
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# echo "server" > /sys/class/net/bat0/mesh/vis_mode
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Each node is either configured as "server" or as "client" (de-
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fault: "client"). Clients send their topology data to the server
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next to them, and server synchronize with other servers. If there
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is no server configured (default) within the mesh, no topology
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information will be transmitted. With these "synchronizing
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servers", there can be 1 or more vis servers sharing the same (or
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at least very similar) data.
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When configured as server, you can get a topology snapshot of
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your mesh:
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# cat /sys/kernel/debug/batman_adv/bat0/vis_data
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This raw output is intended to be easily parsable and convertable
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with other tools. Have a look at the batctl README if you want a
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vis output in dot or json format for instance and how those out-
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puts could then be visualised in an image.
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The raw format consists of comma separated values per entry where
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each entry is giving information about a certain source inter-
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face. Each entry can/has to have the following values:
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-> "mac" - mac address of an originator's source interface
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(each line begins with it)
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-> "TQ mac value" - src mac's link quality towards mac address
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of a neighbor originator's interface which
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is being used for routing
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-> "TT mac" - TT announced by source mac
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-> "PRIMARY" - this is a primary interface
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-> "SEC mac" - secondary mac address of source
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(requires preceding PRIMARY)
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The TQ value has a range from 4 to 255 with 255 being the best.
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The TT entries are showing which hosts are connected to the mesh
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via bat0 or being bridged into the mesh network. The PRIMARY/SEC
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values are only applied on primary interfaces
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LOGGING/DEBUGGING
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-----------------
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All error messages, warnings and information messages are sent to
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the kernel log. Depending on your operating system distribution
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this can be read in one of a number of ways. Try using the com-
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mands: dmesg, logread, or looking in the files /var/log/kern.log
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or /var/log/syslog. All batman-adv messages are prefixed with
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"batman-adv:" So to see just these messages try
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# dmesg | grep batman-adv
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When investigating problems with your mesh network it is some-
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times necessary to see more detail debug messages. This must be
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enabled when compiling the batman-adv module. When building bat-
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man-adv as part of kernel, use "make menuconfig" and enable the
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option "B.A.T.M.A.N. debugging".
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Those additional debug messages can be accessed using a special
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file in debugfs
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# cat /sys/kernel/debug/batman_adv/bat0/log
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The additional debug output is by default disabled. It can be en-
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abled during run time. Following log_levels are defined:
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0 - All debug output disabled
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1 - Enable messages related to routing / flooding / broadcasting
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2 - Enable route or tt entry added / changed / deleted
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3 - Enable all messages
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The debug output can be changed at runtime using the file
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/sys/class/net/bat0/mesh/log_level. e.g.
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# echo 2 > /sys/class/net/bat0/mesh/log_level
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will enable debug messages for when routes or TTs change.
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BATCTL
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------
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As batman advanced operates on layer 2 all hosts participating in
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the virtual switch are completely transparent for all protocols
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above layer 2. Therefore the common diagnosis tools do not work
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as expected. To overcome these problems batctl was created. At
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the moment the batctl contains ping, traceroute, tcpdump and
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interfaces to the kernel module settings.
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For more information, please see the manpage (man batctl).
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batctl is available on http://www.open-mesh.org/
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CONTACT
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-------
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Please send us comments, experiences, questions, anything :)
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IRC: #batman on irc.freenode.org
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Mailing-list: b.a.t.m.a.n@open-mesh.org (optional subscription
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at https://lists.open-mesh.org/mm/listinfo/b.a.t.m.a.n)
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You can also contact the Authors:
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Marek Lindner <lindner_marek@yahoo.de>
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Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
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