[Note:  This comment comes from reader Robert Berger.  DLH]

 

From: “Robert J. Berger” <rberger@ibd.com>

Date: September 2, 2007 2:30:23 PM PDT

To: Dewayne Hendricks <dewayne@warpspeed.com>

Subject: Re: [Dewayne-Net] Sonic.Net, Meraki Team Up For SF ComMuniFi

 

IMHO the Meraki got the price point and the basic concept right (extremely low cost self-organizing bottom up mesh), but their current product won’t scale much better than any of the other wifi meshes that use a single radio (i.e. they don’t scale at all, they collapse at around 30% of their capacity just like early Ethernet did when it was a bridged Hub shared CSMA MAC…

 

Wifi mesh won’t be viable until we develop the equivalent evolutionary step of what Ethernet did when it went from bridged Hubs to Switches. The 802.11 Mac as it stands can’t do scalable meshing. That is because when you add more nodes, they add more contention to the shared medium.

 

This is bad enough when there is one AP being shared by many clients. But when you add multiple adjacent APs relaying thru each other with almost all data from the clients going upstream thru the mesh, one transmission from a client becomes a storm of relayed packets all in a common contention domain. That does not degrade gracefully, it collapses the medium as each failed packet gets retransmitted, fails again due to contention and does that over and over again causing an explosion of contention.

 

But I do think that eventually the 802.11 MAC (or something, like the MAC / PHY being able to use channels and/or coding/timing along with some other PHY info going to the MAC to create non-contending links, but keeping the self-adaptive distributed quality of 802.11) will evolve to allow scalable meshing.

 

But there are only a few proprietary approaches so far that even begins to address this (Skypilot being one, that uses two radios, an adaptive TDMA MAC for their mesh and standard 802.11 for the client access). And there is talk of 802.11s developing some MAC enhancements for meshing, but I don’t know what the status is of that.

 

Note that WiMax 802.16 is the opposite extreme, with a rigid master/slave TDMA style of MAC. It has its own set of problems and does not have the low cost chip sets or evolutionary “fitness” of 802.11, so I don’t see it being a real alternative other than there being one monopoly commercial provider in the US that will have its own problems. But will probably give better results than current 3G cellular services (assuming Sprint doesn’t go bankrupt before they complete the rollout).

 

Rob

 

On Sep 2, 2007, at 11:03 AM, Dewayne Hendricks wrote:

 

Sonic.Net, Meraki Team Up For SF ComMuniFi

 

Written by Om Malik

Friday, August 31, 2007 at 9:49 PM PT

<http://gigaom.com/2007/08/31/sonicnet-meraki-team-up-for-sf-wifi/>

Despite the best efforts of Earthlink (ENLK), Google (GOOG) and Mayor Gavin Newsom, San Francisco MuniFi project is still stuck in neutral and going nowhere fast. For San Francisco residents, a new option has emerged: a tag team of Sonic.net, a Santa Rosa, CA-based independent ISP and Meraki Networks, a wireless hardware company based in Mountain View, Calif., have come up with an ad-supported MuniFi model. (Its actually more like community wifi, and you can call it ComMuniFi.)

 

Sonic.net today notified its customers via email that they can get a Meraki wireless mesh router at a subsidized cost, which will allow them to connect it to their DSL line. The wireless router will share up to 500 kilobits per second of the bandwidth available on the DSL line.

 

Network users will see a Google ad bar at the top of the browser. In the future the ad revenues generated by this ad bar will be split between those who choose to opt and place a wireless router on their connection, and will be credited against their broadband bill.

 

It could be a rather small credit, so don’t get your hopes too high at this stage; this is still experimental and we are still working out many of the details.

Google had to have known all along that their San Francisco grand plan was going to run into political trouble. The big question is why didn’t they roll out a similar service with Earthlink, a much larger ISP with many more broadband customers.

 

[snip]