[IAEP] [Systems] 11s ap's

[Bernie Innocenti]

[this is off-topic on systems@, moving to iaep@]

El Mon, 21-09-2009 a las 09:35 +0200, Marten Vijn escribió:
> FreeBSD 8.0 shipping 802.11s support. 

Do they say anything about scalability?  Because I was under the
impression that 802.11s could not be made to scale well in practice
without major surgery, or at all.

I don't know the details, but this sad possibility sounds "right".
After all, the concept of CSMA/CD was invented because CSMA alone was
unworkable in peer-to-peer networks using a shared channel.  A radio can
hardly receive while transmitting, let alone detect collisions, hence
you're confined within the limits of CSMA.

I'd rather explore asymmetrical networking protocols where nodes can
dynamically become access points, similar to the master browser
elections in Microsoft's SMB/CIFS.  This is just my $0.02 opinion.
Admittedly, I do not have real-world experience with designing and
implementing advanced protocols like these.


> As soon I have time (not in the next 2 weeks) 'll start testing. 
> 
> OLPC's mesh standard is (not tested) probably not standard
> or compatible.

AFAIK, there's no standard, only a draft which leaves a lot of room for
interpretation.  I was told that some of the Marvell deviations from the
standard were required to make the protocol work at all.


> If the XO's are not compatible, is Sugar going to follow the 11s
> standard or OLPC/marvel's standard?

Sugar is protocol agnostic.  The 802.11s implementation of the XO-1
resides entirely in Marvell's proprietary firmware.  The original
purpose of this design was to let laptops to act as mesh routers even
when powered off, using only a minimal amount of power for the embedded
ARM processor.  For various reasons, this idea could not be made to work
and was abandoned long ago.

I also don't know what 802.11s support will be provided by the XO-1.5,
as it switched to a different wireless chip.

The Linux 802.11 stack also implements 802.11s in software, but I don't
know what its status is and what hardware supports it.

-- 
   // Bernie Innocenti - http://codewiz.org/
 \X/  Sugar Labs       - http://sugarlabs.org/