Jeff Duntemanns Drive-By Wi-Fi Guide

The Dream of Mesh Communities

The term 'wireless community networks' embraces a lot of territory, from free community hotspots and 'clouds' (overlapping hotspots that cover a wider area than only one can) to the creation of 'rooftop LANs' of wireless connections that could theoretically span and connect an entire city. To conclude this chapter, I'll need to take a half-step beyond what has been definitively accomplished and talk about the dream of a wirelessly networked town or city. To avoid the confusion inherent in using the broader term 'community network' I prefer to call such a creature a mesh community. The term comes from a group called the Brisbane Mesh in Brisbane, Australia, which in my research most clearly exemplifies the idea. A mesh community is in fact a wireless version of what I predicted in 1993, with my 'Cableton' editorial: A Cableton without cables, using Wi-Fi appliances.

Mesh communities are not about the creation of public hotspots, though public hotspots may be part of the mix. A mesh community has the following general characteristics:

• Individuals create wireless nodes that connect to other wireless nodes with roof-mounted antennas.

• Traffic among nodes is routed, via some kind of router appliance, usually a PC running some flavor of free Unix like Linux.

• Even if there is no connection between the mesh community and the global

Internet, local community servers support Internet protocols like email, chat, newsgroups, and Voice over IP (Internet telephone.)

A mesh community, being a routed network based on Internet protocols, is actually a parallel Internet, which wireless guru Rob Flickenger calls a paranet.

The Brisbane Mesh

Although mesh community projects appear to be popping up almost everywhere, one of the earliest and best-documented is the Brisbane Mesh project in Brisbane, Australia. The project's Web site is here:

http://www.itee.uq.edu.au/~mesh/

A very nice forum (you must register to participate) on Brisbane Mesh is here:

http://www.itee.uq.edu.au/~mesh/forum/

A very active email list server devoted to the Brisbane Mesh may be found here:

http://www.itee.uq.edu.au/~mesh/list/

There are three kinds of nodes in the Brisbane Mesh architecture: Trunk nodes, access nodes, and leaf nodes. Trunk nodes communicate with one another and with access nodes. They form the mesh community backbones, and use high-gain antennas and high-bandwidth access point technologies (like 802.11a) to transport packets in volume across significant distances. Access nodes provide connections to individual leaf nodes that are within easy Wi-Fi distances. Access nodes communicate with one another, and also with trunk nodes. Leaf nodes are for ordinary users without the desire or means to relay packets from other users. This all shows better than it tells, so take a close look at Figure 5.2.

Figure 5.2: The Brisbane Mesh Topology.

The Brisbane Mesh project has a brilliant node directory system that allows prospective participants to determine whether there are any access nodes within line of sight, and provides contact information for node operators. The directory is public and may be found here:

http://www.itee.uq.edu.au/~mesh/db2/index.php

Challenges Facing Mesh Communities

It's still much too soon to say what sort of mechanism works best for a mesh community. We'll need the next several years to see what works and what doesn't, and how well. There are some issues to keep in mind if you're considering launching such a project:

• Even if the connections among mesh participants is free, connection to the global Internet usually is not. Some way of sharing the cost of a connection to the Internet may need to be worked out. Many people will not participate if they can't 'surf the Net' through the connection.

• Most modern suburban subdivisions have a peculiar and deadly hatred of antennas, even small ones. There are deed restrictions that go so far as to prohibit ownership of 'transmitters,' though how enforceable such provisions are has not been tested. The same hateful people who once used deed restrictions to forbid ownership of suburban homes by minorities are behind such things, and they make a hobby of meddling in other people's business. The energy and money they can bring to bear on those who disagree with them can be awesome. If such restrictions exist in your area, your only out may be to use a surplus satellite dish, as such devices have been granted a certain amount of immunity to deed restrictions by the FCC. Investigate carefully, and keep a low-profile.

• The technical burden of coordinating IP addresses and configuring routers is not to be underestimated. Once you exhaust your pool of enthusiastic and network-savvy volunteers, sharing the work required to keep the whole thing coordinated and running may become a serious problem.

• Security remains a gnarly problem, because even with WEP (and soon,

WPA) to exclude outsiders, there is nothing to prevent packet-sniffing by less-than-ethical mesh members. A mesh community has much in common with the old 'party line' rural telephone line sharing systems. Privacy needs to be an added layer on top of the network, using some sort of point-to-point tunneling protocol. More research must be done here, but the problem, while difficult, is not unsolvable.

In short, a mesh community is a very big project, and a great deal of work. Furthermore, you can expect political opposition from several quarters, including the antenna hater crowd and local telecommunications companies who feel that they're being edged out of a market. If that doesn't scare you off, I encourage you to give it a try. The good news is that you can start small, and experiment with the technology with two or three other people in your general vicinity. Once you get a three-house rooftop LAN together and the bugs wrung out, you can begin adding additional nodes within line-of-sight.

For more on community networks you'll need to scour the Web. Rob Flickenger's short book Wireless Community Networks is helpful, but is mostly an overview of the technical issues involved. We don't yet know enough about how community hotspots and mesh communities will work over the long haul for a definitive reference to be written.

Such a book will happen, but it'll be a little while yet. Stay tuned.

In the foreseeable future we can expect to see more and better software systems to make developing and administering wireless community networks easier. As that happens, and perhaps as special hardware bundles and other items drop in price we could start to see quite a bit of growth in this area. There is clearly some economic incentive to enable these projects not to mention the challenge and fun of developing community through technology too.