[wordup] Broadband Block Party

[Adam Shand]

Go Rob.  He kicks ass. :)  

And of course he links to Personal Telco in the online version. :-)

Adam.

From: http://www.pcmag.com/article2/0,4149,31768,00.asp

Broadband Block Party
July 1, 2002
By Rob Flickenger

Throughout the world, a new kind of network is gaining ground. It's
wireless, fast, and easy to use. If the network grows at its current
rate, it may soon become the most widely adopted on the planet.

It's not 3G. It's not run by a three-letter telecom company or a Silicon
Valley start-up. In fact, it doesn't even have a logo (or a business
model). It's called wireless community networking.

Most community groups base their networks on the enormously popular
802.11b standard (also known as Wi-Fi). It's cheap, fast, and highly
interoperable with hardware from different manufacturers. At last count,
the Wireless Communities list at the PersonalTelco Web site showed over
150 projects in scores of cities around the world. But what are those
projects doing?

Some are providing free or low-cost wireless hot spots, where network
patrons can get online from the comfort of the local park or coffee
shop. Others are extending broadband Internet access to regions where
DSL and cable don't yet reach. Perhaps most ambitiously, some are
building networks that are completely independent of traditional,
monopoly-held communication lines, and offering free connections to
anyone who cares to participate.

Although the ultimate goals may differ, a common aim among wireless
network communities harks back to the early days of PCs: the free and
easy exchange of information.

The Technology

The universal cry for tetherless access has brought prices to
astoundingly affordable levels. For a mere $45, anyone can obtain a
wireless client card that not only provides access to nearby networks
but, with the use of proper antennas, can also communicate with other
devices several miles away. For $100 more, you can buy a wireless access
point, a little appliance that lets your client card connect wirelessly
to a conventional wired network.

The low cost, high performance, and widespread use of 802.11b networking
gear have made it highly desirable to consumers and companies alike.
Apple, Dell, and IBM are building notebook computers (and even desktops)
with 802.11b already integrated into the design. This technology is
rapidly becoming as common as Ethernet.

Extending Range

After one gets over the initial excitement of installing a wireless
access point and listening to a streaming Internet radio feed from the
comfort of the couch, thoughts turn to extending range. "How can I get
this at the café across the street?" is a typical line of thinking.
Adding a high-gain antenna to your equipment may help you associate with
your wireless connection from a distance, but no matter how big the
antenna, you won't be able to get a signal everywhere you want. What if
you want to work from the park five blocks away from home? What about
extending broadband access to places where conventional high-speed
service isn't available?

Aside from the technical constraints of getting a radio signal from here
to there, there are also important social constraints to consider.
802.11b operates in the 2.4-GHz ISM (industrial, scientific, and
medical) band, where it shares the air with cordless phones, wireless
cameras, other wireless networks, and more (including Bluetooth
devices). There is only so much spectrum to go around, and one device's
signal is another device's noise. Installing a big omnidirectional
antenna to extend your private network is the social equivalent of
turning your stereo up to full volume so you can hear it at a party two
houses away.

This raises the question: How can everyone get online if spectrum real
estate is scarce?

One approach to extending Internet access is for local residents or
businesses to set up network hot spots in certain areas. A hot spot
typically consists of a wireless access point hooked to the Internet in
some way; via a commercial DSL connection, for example. The access point
is left in open mode (with no encryption or other access control
enabled), but it is connected to a firewall. The firewall runs a
cryptographically secure captive portal application that manipulates the
firewall rules dynamically as people connect to the network and identify
themselves. You'll find a detailed discussion of captive portals here.
One popular open-source captive portal application is NoCatAuth
(http://nocat.net).

The captive portal provides Web site redirection, which you may have
encountered when surfing the Web from hotels that provide DSL access to
rooms. When the Wi-Fi card in your laptop associates with the access
point and you try to open a Web site, you are redirected to an
introduction page that identifies the network and invites you to log on
(sometimes after paying a nominal fee for access). Once cleared with the
authentication service, you are redirected to the site requested.

The hot spot has its place in any community network project because it
is relatively simple to set up and provides immediate benefits. For
little more than the price of the hardware, homes and businesses can use
the wireless network to access a high-speed DSL line (or other
appropriate network connection), sharing its cost. Sponsors can charge
competitive fees for Internet access to help offset the cost of
operations.

The hot spot has one critical limitation: You can set it up only where
high-speed Internet access is already available. What if you want to
extend network access outside of DSL and cable range, or you want to
bridge two networks together but can't afford a dedicated telco line?

Point-To-Point Links

In addition to the point-to-multipoint arrangement of a hot spot,
802.11b works very well with long-distance, point-to-point links. The
broadcast distance depends on three factors: how much power your radios
put out, how much gain your directional antennas provide, and what's in
the way between the two points. Even at the minimal 30-mW power ratings
of most client cards, you can achieve rock-solid 11-Mbps links at
distances of 10 miles or more. The clearer the view between the two
antennas, the better your range will be (a signal falls off sharply when
trying to pass through objects like trees and metal).

As an example, in rural Sonoma County, California, we've had a 5-mile
link online for several months. The path between antennas grazes a few
trees but provides a steady 11-Mbps link. It brings high-speed access
from a commercial DSL connection in town to a remote hill out of town,
very far from the edge of DSL access. This point-to-point link
terminates at a clear spot on the hill, then traditional CAT5 cables
carry the signal to a local network and ultimately to another access
point. This AP serves several families on the hill who can't possibly
see the termination point in town. A PC, access point, or hardware
Ethernet converter acts as the bridge to transfer the signal from wired
to wireless.

Who benefits from this arrangement? As far as we can tell, everyone. The
family hosting the DSL connection enjoys 6-Mbps speed in exchange for
roof access. The families on the hill share the point-to-point link and
help defray the cost of the DSL connection. And the phone company is
getting revenue from a high-end commercial-quality broadband line, which
is more expensive than a residential connection. The DSL rollout up on
the hill isn't expected for five years or more, so this is unexpected
profit for the telco and the ISP.

Get the Gear

If you're thinking of setting up your own point-to-point link, you'll
need the right equipment. Ordinary client PCMCIA cards can go the
distance, but only if connected to high-gain antennas. You'll need a
card with an external antenna connector, and a pigtail adapter to
connect to the antenna. Dish antennas offer exceptionally high gain at
reasonable prices, but they can be difficult to aim. Yagi antennas tend
to be easier to aim and are much more compact than dishes, but they
offer lower gain. Setting up widely separated antennas is a subject
worthy of its own book, but in general, if you can see it, you can shoot
to it. Check out the online resources for more (http://freenetworks.org
is a good starting point).

The Fully Routed Paranet

Once you have a point-to-point link or two online, the question arises:
What would it take to route packets from one link to another? If IP
address space is carefully allocated, any number of point-to-point links
can be connected to one another, and traffic from any node can be routed
through a gateway to any other node without ever touching the live
Internet. Internet independence keeps the transfers quick and free of
charge.

This kind of network is called a paranet, or parallel network. It is
parallel to the existing, wired network infrastructure and so provides
redundancy—and greater reliability than a wired connection alone. Using
802.11b gear for each point-to-point link, the network can achieve a
full 11 Mbps, with latency at each additional hop roughly equivalent to
Ethernet speeds (an added latency of 3 or 4 ms per hop is typical, but
this number is a far cry from the 20 to 30 ms typically seen going
through a DSL hop). See the diagram "A Wireless Community Network
Evolves" for a graphical representation of each stage in the network's
development.

Perhaps most interesting, the only operating costs for point-to-point
links are those of hardware, electricity, and simple maintenance.
Connect enough point-to-point links together and you've built a large,
low-cost community network that offers free high-speed local
connections—perfect for Voice over IP and neighborhood intranets.
Internet connections can then come from anywhere on the local wireless
network, including existing hot spots.

Eventually, this kind of paranet could grow to provide free local VoIP
phone service, unmetered streaming audio and video from local servers at
11 Mbps, and killer network game performance for everybody in town.
Community networking advocates are even thinking about offering
competitively priced Internet connection options, available from any
place in town that has a view of any single point of the network.

I'm writing this article on an Apple iBook connected to a public hot
spot with the connection provided by a point-to-point link to my
neighbor up the road. Our network is fully routed all the way to his
firewall, and I'm streaming an excellent Internet radio station as I
type. By working with your neighbors, you can use proven technology and
techniques to build networks as free as the air we breathe.

Rob Flickenger is the sysadmin of the O'Reilly Network, founder of the
NoCat Community Network group, and author of the book Building Wireless
Community Networks (O'Reilly & Associates).