<br>
<br><tt><font size=2>cananian@gmail.com wrote on 06/08/2008 11:33:15 AM:<br>
<br>
> To clarify, there are at least seven different directions to follow
here:<br>
> a) telepathy-based collaboration on 802.11g networks<br>
> b) telepathy-with-cerebro-backend collaboration on 802.11g networks<br>
> c) cerebro-based collaboration in 802.11g networks.<br>
> d) 802.11s meshing in dense networks<br>
> e) 802.11s meshing in sparse (wide-area) networks<br>
> f) 802.11s Mesh Portal Point functionality (bridging a school
802.11g<br>
> network to a neighborhood 802.11s network)<br>
> g) OLSRd wide-area meshing on an 802.11g sparse (wide-area)
network<br>
> h) plain ol' 802.11g in 100+ node schools<br>
> <br>
> Let me try to summarize current status on a few of these:<br>
> a) what we're currently deploying. believed working for
~20<br>
> machines, but there are problem reports from the field.</font></tt>
<br><tt><font size=2>The number depends on the traffic paterns of the specific
applications.</font></tt>
<br><tt><font size=2>Chat will scale to much higher numbers than write
for example.</font></tt>
<br><tt><font size=2>Careful optimization and debugging is the short term
action path.</font></tt>
<br><tt><font size=2>APs that support high rate multicasts can also help
here.</font></tt>
<br>
<br>
<br><tt><font size=2><br>
> b) collabora did some work to abstract out avahi, in theory
the<br>
> groundwork is present for a cerebro backend.</font></tt>
<br><tt><font size=2>That's more like wishful thinking at this point. We
need to push more on that end.</font></tt>
<br><tt><font size=2><br>
> c) Poly has demonstrated this with 70 laptops (limited only
by the<br>
> size of his testbed); would require modification of activities.</font></tt>
<br><tt><font size=2>Cerebro will work just fine over a mesh transport
also. It uses nearest neighbor broadcast only.</font></tt>
<br><tt><font size=2>We need to settle on a solution for #6211 soon and
we need to get some form of Cerebro into Joyride (not-necessarily integrated
with Telepathy - just a simple D-BUS/UI integration with some Cerebr-ized
apps like chat and file tranfer)</font></tt>
<br><tt><font size=2><br>
> d) nortel and our old mesh testbed looked at this, but I believe<br>
> Michalis' current opinion is that we should be using APs in this<br>
> scenario. So, not important?</font></tt>
<br><tt><font size=2>The bottom line is that there is no need to use a
multi-hop transport with all of its associated overhead, when everybody
can talk to everybody else. We could also be using simple ad-hoc mode,
however we don't support that from a UI perspective. So, for the moment,
we suggest that people use APs. In the long term we should be able to address
the intermediate cases (between sparse and dense) via better broadcast
support on the mesh (ex: Scalable Broadcast Algorithm, Ad-Hoc Broadacast
Protocol) Marvell will be working on this one.</font></tt>
<br><tt><font size=2>It is not clear if we have the necessary memory/cpu
resources on the 8388 but it seems a lot more feasible on the 8682.</font></tt>
<br><tt><font size=2><br>
> e) No one looking at this. Poly has proposed a testbed
for this.</font></tt>
<br><tt><font size=2>I wouldn't call that Wide Area since it involves mobile
devices. It's more of a MANET and less of a WMN (Wireless Mesh Network)</font></tt>
<br><tt><font size=2>We have done testing in the past and Polychronis'
has been doing it in various forms for a long time now.</font></tt>
<br><tt><font size=2><br>
> f) yanni is looking at this? No test bed yet.</font></tt>
<br><tt><font size=2>Ricardo and Yanni (whose last day was Thursday) looked
at that, there is the original scheme adapted so that it doesn't take much
memory and it awaits integration in the builds and (more importantly on
the UI)</font></tt>
<br><tt><font size=2>And given that we have the Active Antenna to think
under the same context as well as an Ethernet adapter and that it operates
at layer-3, lets stop calling it "MPP" and call it "Internet
Sharing" from now on. I will submit a functional spec.</font></tt>
<br>
<br><tt><font size=2><br>
> g) demonstrated in vienna, berlin, and athens with 600+, 800+,
and<br>
> ~2000 nodes. Tradeoff: we can't route w/ CPU power turned off;<br>
> doesn't make progress towards getting 802.11s working for gen2,<br>
> probably requires further tuning for optimal performance in dense<br>
> networks.</font></tt>
<br><tt><font size=2>Again, we are interested in a MANET scenario much
more than a WMN. We are doing the work so that code like that can run on
the XO (in the form of the thin mac driver). I am sure that given the proper
tools present on the XO, people will come up with interesting ways to use
them. I don't see us putting a lot of resources in WMN operation though.</font></tt>
<br>
<br><tt><font size=2><br>
> h) Ricardo looking at this? No test bed that I know of.
We know that<br>
> tweaks are required to get any 802.11x standard to work in a dense<br>
> scenario: media access protocols, probe request/response, beacon<br>
> tuning, etc. Marvell's done some of this tuning already, but
we don't<br>
> have any local resources validating/verifying behavior.</font></tt>
<br><tt><font size=2>Why is that different from a) ? Will it be really
hard to make spectrum out of thin air ? (OLPC's form of Alchemy I guess
;-).</font></tt>
<br><tt><font size=2>Setting aside the fact that we still leak packets/frames
occasionaly in the layer-2 stack, this is more about layer-7 than layer-2</font></tt>
<br>
<br><tt><font size=2><br>
> <br>
> Which should we invest in? Which should we invest in most heavily?<br>
> Let the politicking commence.</font></tt>
<br><tt><font size=2>And let common sense prevail....</font></tt>
<br><tt><font size=2><br>
> --scott<br>
> <br>
M</font></tt>