[Cu-wireless] HSLS?

[Sascha Meinrath]

On Tue, 9 Mar 2004, Todd Boyle wrote:

> At 07:43 PM 3/9/2004, David Young wrote:
> >   You don't really think that we can answer this question, do you? =)
>
>
> Thanks, no of course not, not with any precision!
>
> But what would be your guess, based on the experience
> you've had with the mesh protocols and the senao/soekris
> hardware?
>
> What happens when 3 or 4 nodes on the network
> simultaneously try to move big files on this network?

Well, one of our networks has had 6 nodes and a bunch of regular users on
it for a year now.  Several of the users are rather heavy users.  I've
never noticed any crash, but have occassionally seen the bandwidth
diminish.  Our main bottleneck is the DSL line connecting the network to
the internet -- I suspect that if we had a T1 or the like that this would
still be the case.  Since 802.11 handles collisions by having each node
wait a random interval before resending, I think that even with a dozen or
more nodes, the bottleneck will still be the connection speed to the
internet.

However, the current software will not scale well to scores and scores of
nodes -- which is why we're working on this problem over the next year.
ETX will help, having multiple connection points will help, using radios
where we can automatically set transmit power will help, etc. Either way,
you probably won't see much of a problem until you get many users on the
network (unless you happen to have access to a T3 or something and want
that sort of speed ;).

--Sascha

> http://www.cuwireless.net/images/wirelessmap.jpg
> Not asking for the worst case scenario but really,
> the scenario you'd almost expect, from bandwidth
> hungry users in the evening time..
> Would the throughput
> 1. crash to zero?
> 2.  scale down gracefully?
> 3. become sporadic, randomly, i.e. this is what
> my instincts tell me, but that's based on Internet
> and office LANs when they get overloaded..
> there would be unpredictable latency
>
> Just looking for your guess, ol boy.  You know your
> gear by now... overall, do we get 100Kbps in this situation,
> or 500kbps or 1Mbps?
>
> Many thanks
> Todd
>

-- 
Sascha Meinrath
Project Manager & President      *      Project Manager
Acorn Active Media Foundation   ***     Eggplant Active Media
www.acornactivemedia.com         *      www.eggplantmedia.com