Re: [B.A.T.M.A.N.] updated README

[Andrew Lunn <andrew@lunn.ch>]

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On Mon, May 03, 2010 at 09:33:38AM +0800, Marek Lindner wrote:
> 
> Hey,
> 
> Andrew pointed out that our README would need a little bit of love. I spent 
> some time to get the text into a decent shape. I attached the full file for a 
> review. Let me know if you find anything.  :)

Hi Marek

I reviewed it and made some changes. There are also some suggestion
inside [ ] marks.

       Andrew

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[state: 03-05-2010]

BATMAN-ADV
----------

Batman advanced is a new approach to wireless networking which no
longer operate on the IP level. Unlike the batman daemon, which
exchanges information using UDP packets and sets entries in routing
tables, batman-advanced operates on ISO/OSI Layer 2. It uses and
routes (or better: bridges) Ethernet Frames. It emulates a virtual
network switch containing all of the participating nodes.  Therefore
all nodes appear to be link local to each other. All protocols
operating at higher won't be affected by any changes within the mesh
network. You can run almost any protocol above batman advanced,
prominent examples are: IPv4, IPv6, DHCP and IPX.

Batman advanced is implemented as a Linux kernel driver, so reducing
the overheads 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). It compiles against and
should work with Linux 2.6.20 - 2.6.33.  Supporting older versions is
not planned, but it's probably easy to backport it.  If you work on a
backport, feel free to contact us.  :-)


COMPILE
-------
To compile against your currently installed kernel, just type:

# make

if you want to compile against some other kernel, use:

# make KERNELPATH=/path/to/kernel


CONFIGURATION
-------------

Load the batman-adv module into your kernel:

# insmod batman-adv.ko

The module is now waiting for activation. You must add some interfaces
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 for each supported interface, e.g.

# ls /sys/class/net/eth0/batman_adv/

[Might be nice to show the output here]

If an interface does not have the "batman_adv" subfolder it probably is not
supported. Not supported interfaces are: loopback, non-ethernet and batman's
own interfaces.

Note: After the module is 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 machine 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

[Might be nice to show the contents of the file]

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/

[Might be nice to list the files]

Some of the files contain all sort of status information regarding the
mesh network. For example, you can view the table of originators (mesh
participants) with:

# cat /sys/class/net/bat0/mesh/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

[Might be nice to show the contents of the file]

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 responsive 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 interface. It
needs an IP address which can be either statically configured or
dynamically (by using DHCP or similar services):

# NodeA: ifconfig bat0 192.168.0.1 up
# NodeB: ifconfig bat0 192.168.0.2 up
# NodeB: ping 192.168.0.1

Note: In order to avoid problems remove all IP addresses previously
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" (default:
"client").  Clients send their topology data to the server next to
them, and servers 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/class/net/bat0/mesh/vis_data

This raw output is intended to be easily parsable and convertible 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 outputs 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 interface. 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 commands: 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 sometimes
necessary to see more detail debug messages. This must be enabled when
compiling the batman-adv module. When building batman-adv as part of
kernel, use "make menuconfig" and enable the option
"B.A.T.M.A.N. debugging". When compiling outside of the kernel tree it
is necessary to edit the file Makefile.kbuild and uncomment the line

#EXTRA_CFLAGS += -DCONFIG_BATMAN_ADV_DEBUG

The additional debug output is by default disabled. It can be enabled
either at kernel modules load time or during run time. To enable debug
output at module load time, add the module parameter debug=<value>.
<value> can take one of four values.

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

e.g.

# modprobe batman-adv debug=2

will load the module and enable debug messages for when routes or HNAs
change.

The debug output can also be changed at run time using the file
/sys/module/batman-adv/parameters/debug. e.g.

# echo 2 > /sys/module/batman-adv/parameters/debug

enables debug messages for when routes or HNAs

The debug output is sent to the kernel logs. So try dmesg, logread,
etc to see the debug messages.


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.net
(optional subscription at https://lists.open-mesh.org/mm/listinfo/b.a.t.m.a.n)

You can also contact the Authors:

Marek Lindner <lindner_marek@yahoo.de>
Simon Wunderlich <siwu@hrz.tu-chemnitz.de>