[Testing] first play with new XO 1.5 machines

Daniel Drake dsd at laptop.org
Wed Oct 21 22:03:06 EDT 2009

2009/10/22 Martin Langhoff <martin.langhoff at gmail.com>:
> They are -- but it's pretty awkward to activate. I am arguing that
> ad-hoc networking with a preset ESSID, and Salut should be the
> transparent fallback. Just like the mesh was on earlier releases.

We already discussed this a lot in another thread. It should not be
automatic. The thread is titled "[Sugar-devel] [Design] Ad-hoc
networks - New Icons"

The biggest headache about mesh is the cases where it sort-of-works,
but not quite. Ad-hoc networking will be considerably less reliable
than mesh was, for a few reasons:

1. In the mesh, everyone does their own beaconing. Sounds horrible but
it actually works.
In ad-hoc, there is just one beacon master. Due to cheap radios and
interference etc, the beacon master will switch around frequently
causing frequent network splits and communication failures.

2. This kind of situation will happen frequently:

A <-----> B <-----> C

B can see both users A and C on his network view. A can only see B,
and C can only see B.
B shares an activity. Both A and C join. However, anything done by A
cannot be seen by C and vice-versa, because they are too far apart.

3. Another nasty situation

A -------------------------- B

A and B are outside of radio range, but are both setup to start an
automatic network named "olpc"
So they both setup their own ad-hoc networks, both becoming beacon masters.

Another laptop "C" comes along
A <--------> C <----------> B
This laptop can see both of these independent laptops (each having its
independent network). It can join one or the other. It cannot join
both. Hence this XO can only communicate with A or B, but not both
(even though the range is OK), and presenting this choice in the UI
would be nasty.

Ad-hoc will work well for the cases where the children get together in
a small space and explicitly create a throwaway network. If it is
created automatically, I predict we will just get an unreliable mess.


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