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B.A.T.M.A.N. Layer 3 meshing guide

Installing from source

Pre-requirements

Compiling

All you have to do is untar and make, then you will see the executable file called batmand.

$ wget \
https://downloads.open-mesh.org/batman/stable/sources/batman/batman-0.3.tar.gz
$ tar xzvf batman-0.3.tar.gz
$ cd batman-0.3
$ make

If you want reduce the size of executable file, just strip it by executing:

$ strip batmand

Note that if you want to help us finding a bug in the daemon, please don't strip it.

Installing

Copy batmand to a location somewhere in your path, for example

$ cp batmand /usr/sbin/

Or start it right from the directory where you compiled it

$ ./batmand

Usage

If you execute batmand -h or -H, you will see the help page, in the following we will explain all parameters and how to work with them in a mesh network.

SYNOPSIS

batmand [options] {interface} [interface]

DESCRIPTION

You can start batmand without specifying options, but you have to choose at least one interface batmand runs on.

$ batmand eth1

If you have more interfaces, then you just add them behind the first.

$ batmand eth1 eth2 eth3

The B.A.T.M.A.N. daemon can also run on alias interfaces. Note that we use alias interfaces to separate B.A.T.M.A.N. routing protocol and olsr routing protocol.

$ batmand eth1:test1 eth2:test2 eth3:test3

Note that the B.A.T.M.A.N. daemon will take the ip address and the broadcast address from the given interfaces.

Note also that you have to check whether your essid, channel or wifi mode is correct or not.

-a add announced network(s)

The daemon announces the availability of a connection to another network. This option can be used multiple times and can be used to add networks dynamically while the daemon is running. The parameter has to be in the form of ip-address/netmask.

For example, if you are the node A, and you can connect to other network, then you can execute -a to announce the gateway.

Announce A as gateway to B
Announce A as gateway to B

If the other nodes in the B.A.T.M.A.N. network want to connect to node B after receiving the announce network information form node A, then they will know they can use node A as gateway to reach node B. Now, you know what a announced network is, but executing this command is wrong:

$ batmand -a 192.168.100.101 eth1

Because you have to specify the netmask parameter and different netmask parameters cause different results. Let's make a example:

$ batmand -a 192.168.100.101/32 eth1

In this case, it means that node A can only connect to node B, because your parameter is /32.

$ batmand -a 192.168.100.101/24 eth1

In this case, it means that node A can connect to the whole 192.168.100.x network, because your parameter is /24. So, if you use different netmask values, then the results are different.

Two Announced Networks
Two Announced Networks

Node A can announce more than one network. To announce two networks execute the following command:

$ batmand -a 192.168.100.101/24 -a 192.168.200.201/24 eth1

Note that node A has to have a route to connect the node or network.

-A delete announced network(s)

Delete networks to the daemons list of available connections to another network(s). This option can be used multiple times and can only be used while the daemon is running. The parameter has to be in the form of ip-address/netmask.

-b run connection in batch mode

The debug information are updated after a period of time by default, so if you use "-b" it will execute once and then stop.

$ batmand eth1
$ batmand -b -c -d 1

In this case, it means run debug level 1 once.

Note that -b can only be used with -c and debug level 1 & 2.

-c connect via unix socket

The B.A.T.M.A.N. daemon offers a unix socket interface to which you can connect. First, you have to create a B.A.T.M.A.N. daemon on your host, then use -c to connect to its interface. Note you can create as many client sockets as you like. Deploy it without any arguments to get the current configuration even if changed at runtime.

Multiple clients connected to B.A.T.M.A.N. interface
Multiple clients connected to B.A.T.M.A.N. interface

$ batmand eth1
$ batmand -c -d 1

In this case, you ask the daemon to output debug level 1 in your current shell. The B.A.T.M.A.N. daemon will update the information after a period of time.

Note that if you use -c flag, then you only can use -d to see the debug level.

-d debug level

The debug level can be set to five values.

  • 0 - debug turned off (default)
  • 1 - list neighbors
  • 2 - list gateways
  • 3 - observe batmand
  • 4 - observe batmand (very verbose)
  • 5 - memory debug / cpu usage

Note that debug level 5 can be turned off at compile time.

For example, you can run in normal start:

$ batmand -d 1 eth1
Level 1

just lists the neighbors in your B.A.T.M.A.N. network.

Originator      Router (#/128):       Potential routers... [B.A.T.M.A.N. 0.2,
MainIF/IP: eth2 105.131.131.175, UT: 0d 0h 3m]
105.131.83.2    105.131.1.3 (  71):   105.131.1.3 (  71)
105.131.1.2     105.131.1.2 (  52):   105.131.1.2 (  52)
105.131.56.10   105.131.1.4 (  25):   105.131.1.4 (  25),105.131.1.6 ( 15),...
105.131.131.70  105.131.131.70 (121): 105.131.131.70 (121)
  • In the first line, we will see the version of the B.A.T.M.A.N. daemon, main interface, main IP, and uptime.
  • In the first column, we can see those IPs which we can reach.
  • In the second column, we can see those IPs which we sent our packets to when we want to reach the IP of the first column. The number in the parenthesis indicates the link quality of the connection and the #/128 shows the maximum number of packets.
  • In the third column, we can see those IPs which are one hop neighbors and rebroadcasted packets from the originator. The B.A.T.M.A.N. daemon will choose the router with the best link quality from the potential router list.

In this case, 105.131.1.2 is a one hop neighbor of 105.131.131.175, because the 105.131.1.2 is originator, router and potential router at the same time. If 105.131.131.175 wants to exchange data with the 105.131.83.2, then it will sent its packets to the 105.131.1.3, because it is the router for this destination.

Level 2

just lists gateways in the B.A.T.M.A.N. network.

Gateway         Router (#/128)
105.131.83.5    105.131.41.1 ( 57), gw_class 11  ->6 MBit, reliability: 0
105.131.41.5    105.131.41.1 ( 53), gw_class 11  ->6 MBit, reliability: 0
  • In the first column, we can see those IPs which are our gateways.
  • In the second column, we can see those IPs which we sent our packets to when we want to reach the IP of the first column. The number in the parenthesis indicates the link quality of the connection and the #/128 shows the maximum number of packets. The gw_class means gateway class of the gateway and 11 ->6 MBit means how much bandwidth the gateway owner wants to share. The reliability means how good the quality of the internet connection is. In this case, 0 means this is the best quality. The reliability number will increase if the quality is poor.
Level 3

has more information about the neighbors, or shows the error message when you have an incorrect command. Note that if there is no neighbor in the B.A.T.M.A.N. network, then it will display nothing.

Level 4

has so many information about the B.A.T.M.A.N. network, for example, how many packets you sent, and sent to where, or how many packets you got, and received from where etc.

-g gateway class

The gateway class is used to tell other nodes in the network your available internet bandwidth. Just enter any number (optionally followed by "kbit" or "mbit") and the daemon will guess your appropriate gateway class. Use "/" to seperate the down- and upload rates. You can omit the upload rate and batmand will assume an upload of .

  • 5000
  • 5000kbit
  • 5mbit
  • 5mbit/1024
  • 5mbit/1024kbit
  • 5mbit/1mbit

You only can set the value in a normal start

$ batmand -g 5mbit/1024 -d 3 eth1

Note that if you use debug level 3, then you will know whether you succeed setting the gateway class or not.

-o originator interval in ms

A node transmits broadcast messages (we call them originator message or OGM) to inform the neighboring nodes about it's existence. Originator interval is the time to wait after sending one message and before sending the next message. The default value is 1000 ms (1 second). In a mobile network, you may want to detect network changes very quickly, so you need to send message very often, for example, use a value of 500 ms. In a static network, you can save bandwidth by using a higher value. This option is only available in daemon mode.

$ batmand -o 2000 eth1

In this case, batmand will wait 2 second until sending the next OGMs.

-p preferred gateway

Set the internet gateway by yourself.

Note that this automatically switches your B.A.T.M.A.N. daemon to "internet search modus" with "-r 1" unless "-r" is given. If the preferred gateway is not found the gateway selection will use the current routing class to choose a gateway.

$ batmand -r 3 -d 3 -p 192.168.1.1 eth1

In this case, you set 192.168.1.1 as your preferred gateway, so all of your internet packets will be sent to the 192.168.1.1.

-r routing class

The routing class can be set to four values - it enables "internet search modus". The daemon will choose an internet gateway based on certain criteria (unless "-p" is specified):

  • 0 - set no default route (default)
  • 1 - use fast connection
  • 2 - use stable connection
  • 3 - use fast-switch connection
  • XX - use late-switch connection
Level 1

B.A.T.M.A.N tries to find the best available connection by watching the uplinks throughput and the link quality.

Level 2

B.A.T.M.A.N compares the link quality of the internet node and chooses the one with the best connection.

Level 3

B.A.T.M.A.N compares the link quality of the internet node and chooses the one with the best connection but switches to another gateway as soon as a better connection is found.

Level XX

B.A.T.M.A.N compares the link quality of the internet node and chooses the one with the best link quality but switches to another gateway as soon as this gateway has a TQ value which is XX better than the currently selected gateway.

XX ist a number between 3 and 256

$ batmand -r 3 -d 3 eth1

In this case, the B.A.T.M.A.N. daemon will choose the best statistic internet connection for you. Note that if you use debug level 3, then you will know whether you succeeded setting the routing class or not.

-s visualization server

Since no topology database is computed by the protocol an additional solution to create topology graphs has been implemented, the vis server. B.A.T.M.A.N. daemons may send their local view about their single-hop neighbors to the vis server. It collects the information and provides data in a format similar to OLSR's topology information output. Therefore existing solutions to draw topology graphs developed for OLSR can be used to visualize mesh-clouds using B.A.T.M.A.N.

--policy-routing-script

This option turns off the policy routing feature of batmand - all routing changes are send to the script which can make use of this information or not. Firmware and package maintainers can use this option to tightly integrate batmand into their own routing policies. This option is only available in daemon mode.

Troubleshooting

Why the B.A.T.M.A.N. daemon doesn't reload the setting after I fixed the main IP?

You have to restart the B.A.T.M.A.N. daemon after you modified any network configuration, otherwise the B.A.T.M.A.N. daemon won't use the new settings.

$ killall batmand
$ batmand eth1

Why I can't connect to the Internet after setting the default gateway?

You have to use NAT on your gateway or firewall if you use the -r or -p options to set default route.

$ iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE

Note that you don't set the default route by yourself.