Babel
*****
Babel is a loop-avoiding distance-vector routing protocol roughly
based on HSDV and AODV, but with provisions for link cost estimation
and redistribution of routes from other routing protocols.
Installation
************
$ make
$ su -c 'make install'
If compiling for OpenWRT, you will probably want to say something like
$ make CC=mipsel-linux-gcc PLATFORM_DEFINES='-march=mips32'
Setting up a network for use with Babel
***************************************
1. Choose a prefix
==================
You will want your mesh network to run on a single /64 prefix. If
you've already got IPv6 routing with the rest of the Internet (either
native or using 6to4) and you've got a /64 to spare, use that.
If you don't, you can generate a random prefix. RFC 4193 defines how
such prefixes are generated. The simplest way to make sure that you
follow the rules is to use the utility ``ahcp-generate-address'',
which you'll find in the AHCP package.
$ ahcp-generate-address -p -r
fdf0:bb4:f192::
This needs to be done only once for the network; the following steps
need to be repeated for every node.
2. Choose a host number
=======================
You will need to choose a unique host number for every node. You can
number your nodes sequentially (fdf0:bb4:f192::1, fdf0:bb4:f192::2,
etc.), generate a node number from the interface's MAC address, or
choose it randomly. Again, ``ahcp-generate-address'' knows the rules.
$ ip -0 addr show dev eth1
3: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 1000
link/ieee1394 00:11:d8:00:00:12:34:56 brd ff:ff:ff:ff:ff:ff:ff:ff
$ ahcp-generate-address fdf0:bb4:f192:: 00:11:d8:00:00:12:34:56
fdf0:bb4:f192:0:211:d8ff:fe00:12
This is your IPv6 address; save it for later use.
$ IPv6=fdf0:bb4:f192:0:211:d8ff:fe00:12
3. Set up the interface
=======================
Set up the MAC layer's parameters first:
$ iwconfig eth1 mode ad-hoc channel 11
$ iwconfig eth essid "my-wireless-network"
Then the network layer:
$ ip link set eth1 up
$ ip -6 addr add $IPv6 dev eth1
4. Start the routing daemon
===========================
$ babel -X $IPv6 0 $IPv6 eth1
If your node has multiple interfaces which you want to participate in
the Babel network, just list them all:
# babel -X $IPv6 0 $IPv6 eth0 eth1 sit1
If your node has multiple addresses and you want all of them to
participate in the routing protocol, just repeat the ``-X'' option
multiple times:
# babel -X $IPv6 0 -X $IPv6-2 0 -X $IPv6-3 0 $IPv6 eth1
On a gateway to the Internet, you'll want to redistribute the default
route into the mesh network:
# babel -X $IPv6 0 -x default 256 $IPv6 eth1
If you find all of this too complicated and error-prone (as I do), you
may want to consider autoconfiguring your routing domain using AHCP:
http://www.pps.jussieu.fr/~jch/software/ahcp/
Juliusz Chroboczek