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| 1 | +[state: 21-11-2010] |
| 2 | + |
| 3 | +BATMAN-ADV |
| 4 | +---------- |
| 5 | + |
| 6 | +Batman advanced is a new approach to wireless networking which |
| 7 | +does no longer operate on the IP basis. Unlike the batman daemon, |
| 8 | +which exchanges information using UDP packets and sets routing |
| 9 | +tables, batman-advanced operates on ISO/OSI Layer 2 only and uses |
| 10 | +and routes (or better: bridges) Ethernet Frames. It emulates a |
| 11 | +virtual network switch of all nodes participating. Therefore all |
| 12 | +nodes appear to be link local, thus all higher operating proto- |
| 13 | +cols won't be affected by any changes within the network. You can |
| 14 | +run almost any protocol above batman advanced, prominent examples |
| 15 | +are: IPv4, IPv6, DHCP, IPX. |
| 16 | + |
| 17 | +Batman advanced was implemented as a Linux kernel driver to re- |
| 18 | +duce the overhead to a minimum. It does not depend on any (other) |
| 19 | +network driver, and can be used on wifi as well as ethernet lan, |
| 20 | +vpn, etc ... (anything with ethernet-style layer 2). |
| 21 | + |
| 22 | +CONFIGURATION |
| 23 | +------------- |
| 24 | + |
| 25 | +Load the batman-adv module into your kernel: |
| 26 | + |
| 27 | +# insmod batman-adv.ko |
| 28 | + |
| 29 | +The module is now waiting for activation. You must add some in- |
| 30 | +terfaces on which batman can operate. After loading the module |
| 31 | +batman advanced will scan your systems interfaces to search for |
| 32 | +compatible interfaces. Once found, it will create subfolders in |
| 33 | +the /sys directories of each supported interface, e.g. |
| 34 | + |
| 35 | +# ls /sys/class/net/eth0/batman_adv/ |
| 36 | +# iface_status mesh_iface |
| 37 | + |
| 38 | +If an interface does not have the "batman_adv" subfolder it prob- |
| 39 | +ably is not supported. Not supported interfaces are: loopback, |
| 40 | +non-ethernet and batman's own interfaces. |
| 41 | + |
| 42 | +Note: After the module was loaded it will continuously watch for |
| 43 | +new interfaces to verify the compatibility. There is no need to |
| 44 | +reload the module if you plug your USB wifi adapter into your ma- |
| 45 | +chine after batman advanced was initially loaded. |
| 46 | + |
| 47 | +To activate a given interface simply write "bat0" into its |
| 48 | +"mesh_iface" file inside the batman_adv subfolder: |
| 49 | + |
| 50 | +# echo bat0 > /sys/class/net/eth0/batman_adv/mesh_iface |
| 51 | + |
| 52 | +Repeat this step for all interfaces you wish to add. Now batman |
| 53 | +starts using/broadcasting on this/these interface(s). |
| 54 | + |
| 55 | +By reading the "iface_status" file you can check its status: |
| 56 | + |
| 57 | +# cat /sys/class/net/eth0/batman_adv/iface_status |
| 58 | +# active |
| 59 | + |
| 60 | +To deactivate an interface you have to write "none" into its |
| 61 | +"mesh_iface" file: |
| 62 | + |
| 63 | +# echo none > /sys/class/net/eth0/batman_adv/mesh_iface |
| 64 | + |
| 65 | + |
| 66 | +All mesh wide settings can be found in batman's own interface |
| 67 | +folder: |
| 68 | + |
| 69 | +# ls /sys/class/net/bat0/mesh/ |
| 70 | +# aggregated_ogms bonding fragmentation orig_interval |
| 71 | +# vis_mode |
| 72 | + |
| 73 | + |
| 74 | +There is a special folder for debugging informations: |
| 75 | + |
| 76 | +# ls /sys/kernel/debug/batman_adv/bat0/ |
| 77 | +# originators socket transtable_global transtable_local |
| 78 | +# vis_data |
| 79 | + |
| 80 | + |
| 81 | +Some of the files contain all sort of status information regard- |
| 82 | +ing the mesh network. For example, you can view the table of |
| 83 | +originators (mesh participants) with: |
| 84 | + |
| 85 | +# cat /sys/kernel/debug/batman_adv/bat0/originators |
| 86 | + |
| 87 | +Other files allow to change batman's behaviour to better fit your |
| 88 | +requirements. For instance, you can check the current originator |
| 89 | +interval (value in milliseconds which determines how often batman |
| 90 | +sends its broadcast packets): |
| 91 | + |
| 92 | +# cat /sys/class/net/bat0/mesh/orig_interval |
| 93 | +# 1000 |
| 94 | + |
| 95 | +and also change its value: |
| 96 | + |
| 97 | +# echo 3000 > /sys/class/net/bat0/mesh/orig_interval |
| 98 | + |
| 99 | +In very mobile scenarios, you might want to adjust the originator |
| 100 | +interval to a lower value. This will make the mesh more respon- |
| 101 | +sive to topology changes, but will also increase the overhead. |
| 102 | + |
| 103 | + |
| 104 | +USAGE |
| 105 | +----- |
| 106 | + |
| 107 | +To make use of your newly created mesh, batman advanced provides |
| 108 | +a new interface "bat0" which you should use from this point on. |
| 109 | +All interfaces added to batman advanced are not relevant any |
| 110 | +longer because batman handles them for you. Basically, one "hands |
| 111 | +over" the data by using the batman interface and batman will make |
| 112 | +sure it reaches its destination. |
| 113 | + |
| 114 | +The "bat0" interface can be used like any other regular inter- |
| 115 | +face. It needs an IP address which can be either statically con- |
| 116 | +figured or dynamically (by using DHCP or similar services): |
| 117 | + |
| 118 | +# NodeA: ifconfig bat0 192.168.0.1 |
| 119 | +# NodeB: ifconfig bat0 192.168.0.2 |
| 120 | +# NodeB: ping 192.168.0.1 |
| 121 | + |
| 122 | +Note: In order to avoid problems remove all IP addresses previ- |
| 123 | +ously assigned to interfaces now used by batman advanced, e.g. |
| 124 | + |
| 125 | +# ifconfig eth0 0.0.0.0 |
| 126 | + |
| 127 | + |
| 128 | +VISUALIZATION |
| 129 | +------------- |
| 130 | + |
| 131 | +If you want topology visualization, at least one mesh node must |
| 132 | +be configured as VIS-server: |
| 133 | + |
| 134 | +# echo "server" > /sys/class/net/bat0/mesh/vis_mode |
| 135 | + |
| 136 | +Each node is either configured as "server" or as "client" (de- |
| 137 | +fault: "client"). Clients send their topology data to the server |
| 138 | +next to them, and server synchronize with other servers. If there |
| 139 | +is no server configured (default) within the mesh, no topology |
| 140 | +information will be transmitted. With these "synchronizing |
| 141 | +servers", there can be 1 or more vis servers sharing the same (or |
| 142 | +at least very similar) data. |
| 143 | + |
| 144 | +When configured as server, you can get a topology snapshot of |
| 145 | +your mesh: |
| 146 | + |
| 147 | +# cat /sys/kernel/debug/batman_adv/bat0/vis_data |
| 148 | + |
| 149 | +This raw output is intended to be easily parsable and convertable |
| 150 | +with other tools. Have a look at the batctl README if you want a |
| 151 | +vis output in dot or json format for instance and how those out- |
| 152 | +puts could then be visualised in an image. |
| 153 | + |
| 154 | +The raw format consists of comma separated values per entry where |
| 155 | +each entry is giving information about a certain source inter- |
| 156 | +face. Each entry can/has to have the following values: |
| 157 | +-> "mac" - mac address of an originator's source interface |
| 158 | + (each line begins with it) |
| 159 | +-> "TQ mac value" - src mac's link quality towards mac address |
| 160 | + of a neighbor originator's interface which |
| 161 | + is being used for routing |
| 162 | +-> "HNA mac" - HNA announced by source mac |
| 163 | +-> "PRIMARY" - this is a primary interface |
| 164 | +-> "SEC mac" - secondary mac address of source |
| 165 | + (requires preceding PRIMARY) |
| 166 | + |
| 167 | +The TQ value has a range from 4 to 255 with 255 being the best. |
| 168 | +The HNA entries are showing which hosts are connected to the mesh |
| 169 | +via bat0 or being bridged into the mesh network. The PRIMARY/SEC |
| 170 | +values are only applied on primary interfaces |
| 171 | + |
| 172 | + |
| 173 | +LOGGING/DEBUGGING |
| 174 | +----------------- |
| 175 | + |
| 176 | +All error messages, warnings and information messages are sent to |
| 177 | +the kernel log. Depending on your operating system distribution |
| 178 | +this can be read in one of a number of ways. Try using the com- |
| 179 | +mands: dmesg, logread, or looking in the files /var/log/kern.log |
| 180 | +or /var/log/syslog. All batman-adv messages are prefixed with |
| 181 | +"batman-adv:" So to see just these messages try |
| 182 | + |
| 183 | +# dmesg | grep batman-adv |
| 184 | + |
| 185 | +When investigating problems with your mesh network it is some- |
| 186 | +times necessary to see more detail debug messages. This must be |
| 187 | +enabled when compiling the batman-adv module. When building bat- |
| 188 | +man-adv as part of kernel, use "make menuconfig" and enable the |
| 189 | +option "B.A.T.M.A.N. debugging". |
| 190 | + |
| 191 | +Those additional debug messages can be accessed using a special |
| 192 | +file in debugfs |
| 193 | + |
| 194 | +# cat /sys/kernel/debug/batman_adv/bat0/log |
| 195 | + |
| 196 | +The additional debug output is by default disabled. It can be en- |
| 197 | +abled during run time. Following log_levels are defined: |
| 198 | + |
| 199 | +0 - All debug output disabled |
| 200 | +1 - Enable messages related to routing / flooding / broadcasting |
| 201 | +2 - Enable route or hna added / changed / deleted |
| 202 | +3 - Enable all messages |
| 203 | + |
| 204 | +The debug output can be changed at runtime using the file |
| 205 | +/sys/class/net/bat0/mesh/log_level. e.g. |
| 206 | + |
| 207 | +# echo 2 > /sys/class/net/bat0/mesh/log_level |
| 208 | + |
| 209 | +will enable debug messages for when routes or HNAs change. |
| 210 | + |
| 211 | + |
| 212 | +BATCTL |
| 213 | +------ |
| 214 | + |
| 215 | +As batman advanced operates on layer 2 all hosts participating in |
| 216 | +the virtual switch are completely transparent for all protocols |
| 217 | +above layer 2. Therefore the common diagnosis tools do not work |
| 218 | +as expected. To overcome these problems batctl was created. At |
| 219 | +the moment the batctl contains ping, traceroute, tcpdump and |
| 220 | +interfaces to the kernel module settings. |
| 221 | + |
| 222 | +For more information, please see the manpage (man batctl). |
| 223 | + |
| 224 | +batctl is available on http://www.open-mesh.org/ |
| 225 | + |
| 226 | + |
| 227 | +CONTACT |
| 228 | +------- |
| 229 | + |
| 230 | +Please send us comments, experiences, questions, anything :) |
| 231 | + |
| 232 | +IRC: #batman on irc.freenode.org |
| 233 | +Mailing-list: [email protected]@lists.open-mesh.org |
| 234 | + (optional subscription at |
| 235 | + https://lists.open-mesh.org/mm/listinfo/b.a.t.m.a.n) |
| 236 | + |
| 237 | +You can also contact the Authors: |
| 238 | + |
| 239 | + |
| 240 | +Simon Wunderlich < [email protected]> |
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