Wireless mesh networks are self organising and self healing
networks that can be used to connect computers across small and large
areas, depending on the radio technology used. Normal wifi equipment
can be used to create home made radio networks, and there are several
successful examples like
Freifunk and
Athens Wireless Metropolitan Network
(see
wikipedia
for a large list) around the globe. To give you an idea how it
work, check out the nice overview of the Kiel Freifunk community which
can be seen from their
dynamically
updated node graph and map, where one can see how the mesh nodes
automatically handle routing and recover from nodes disappearing.
There is also a small community mesh network group in Oslo, Norway,
and that is the main topic of this blog post.
I've wanted to check out mesh networks for a while now, and hoped
to do it as part of my involvement with the NUUG member organisation community, and
my recent involvement in
the Freedombox project
finally lead me to give mesh networks some priority, as I suspect a
Freedombox should use mesh networks to connect neighbours and family
when possible, given that most communication between people are
between those nearby (as shown for example by research on Facebook
communication patterns). It also allow people to communicate without
any central hub to tap into for those that want to listen in on the
private communication of citizens, which have become more and more
important over the years.
So far I have only been able to find one group of people in Oslo
working on community mesh networks, over at the hack space
Hackeriet at Husmania. They seem to
have started with some Freifunk based effort using OLSR, called
the Oslo
Freifunk project, but that effort is now dead and the people
behind it have moved on to a batman-adv based system called
meshfx. Unfortunately the wiki
site for the Oslo Freifunk project is no longer possible to update to
reflect this fact, so the old project page can't be updated to point to
the new project. A while back, the people at Hackeriet invited people
from the Freifunk community to Oslo to talk about mesh networks. I
came across this video where Hans Jørgen Lysglimt interview the
speakers about this talk (from
youtube):
I mentioned OLSR and batman-adv, which are mesh routing protocols.
There are heaps of different protocols, and I am still struggling to
figure out which one would be "best" for some definitions of best, but
given that the community mesh group in Oslo is so small, I believe it
is best to hook up with the existing one instead of trying to create a
completely different setup, and thus this have decided to focus on
batman-adv for now. It sure help me to know that the very cool
Serval project in Australia
is using batman-adv as their meshing technology when it create a self
organizing and self healing telephony system for disaster areas and
less industrialized communities. Check out this cool video presenting
that project (from
youtube):
According to the wikipedia page on
Wireless
mesh network there are around 70 competing schemes for routing
packets across mesh networks, and OLSR, B.A.T.M.A.N. and
B.A.T.M.A.N. advanced are protocols used by several free software
based community mesh networks.
The batman-adv protocol is a bit special, as it provide layer 2
(as in ethernet ) routing, allowing ipv4 and ipv6 to work on the same
network. One way to think about it is that it provide a mesh based
vlan you can bridge to or handle like any other vlan connected to your
computer. The required drivers are already in the Linux kernel at
least since Debian Wheezy, and it is fairly easy to set up. A
good
introduction is available from the Open Mesh project. These are
the key settings needed to join the Oslo meshfx network:
Setting
Value
Protocol / kernel module
batman-adv
ESSID
meshfx@hackeriet
Channel / Frequency
11 / 2462
Cell ID
02:BA:00:00:00:01
The reason for setting ad-hoc wifi Cell ID is to work around bugs
in firmware used in wifi card and wifi drivers. (See a nice post from
VillageTelco about
"Information
about cell-id splitting, stuck beacons, and failed IBSS merges!
for details.) When these settings are activated and you have some
other mesh node nearby, your computer will be connected to the mesh
network and can communicate with any mesh node that is connected to
any of the nodes in your network of nodes. :)
My initial plan was to reuse my old Linksys WRT54GL as a mesh node,
but that seem to be very hard, as I have not been able to locate a
firmware supporting batman-adv. If anyone know how to use that old
wifi access point with batman-adv these days, please let me know.
If you find this project interesting and want to join, please join
us on IRC, either channel
#oslohackerspace
or #nuug on
irc.freenode.net.
While investigating mesh networks in Oslo, I came across an old
research paper from the university of Stavanger and Telenor Research
and Innovation called
The
reliability of wireless backhaul mesh networks and elsewhere
learned that Telenor have been experimenting with mesh networks at
Grünerløkka in Oslo. So mesh networks are also interesting for
commercial companies, even though Telenor discovered that it was hard
to figure out a good business plan for mesh networking and as far as I
know have closed down the experiment. Perhaps Telenor or others would
be interested in a cooperation?