[GLLUG] Mesh Networks

[Charles Ulrich]

On Fri, Mar 18, 2011 at 10:35 PM, Chick Tower <c.e.tower at gmail.com> wrote:
> When Egypt was cut off from the internet, I remember reading that people
> could set up mesh networks with their PCs and still communicate that way.
>  However, I didn't see _how_ they would communicate.  Would they use IM,
> IRC, e-mail, or what?  Does anyone know?

I guess it depends on whether there are points on the mesh that act as
Internet gateways. If so, and if those are reliable enough, then they
just continue to use Internet services (Twitter, etc) as usual.

If there are no Internet gateways on the mesh, then there are several
problems. The biggest being that the only realistic option for
semi-reliable communication would be peer-to-peer applications.
Unfortunately, there aren't many P2P replacements for common
Internet-style applications. We have bittorrent for larger chunks of
isolated content, but nothing that I know of can replace web browsing,
email, and instant messaging in a P2P fashion.

The other issue is that wifi signals are, by design, pretty weak. Even
in a densely-populated area, there would be many small clusters of a
few stations which can talk to each other, but none are close enough
to a neighboring cluster to join the networks together. Or, the few
that are would get overwhelmed with traffic. Each station needs to
have a radio that can reach dozens to hundreds of other stations
because the only way to compensate for the massive instability in a
mesh network is by massive redundancy and smart algorithms which can
pick the best (say) five peers out of a hundred. Not even
well-developed countries like the U.S. have mass-market wireless
equipment that can do this, and we definitely don't have the radio
spectrum for such devices to operate in.

> Would this be something we could try at a meeting, to set up our own little
> mesh network and use it?  What would we need, other than our PCs, wireless
> cards, and the standard software that comes in a Linux distro?

There is apparently software out there to deploy and manage mesh
networks (say, if you have a lot of property and have to cover it with
a bunch of access points), but we could probably get a sense for what
a real-world "guerilla" mesh network would look like just by
disassociating from the Gone Wired AP and setting up an ad-hoc wifi
network. (Spoiler: it will be a lot like plugging our laptops into an
ethernet switch with no uplink.)

Charles
-- 
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