Faster Multicast [was Re: WatchMe-1, a VNC activity]

[david at lang.hm]

On Wed, 12 Aug 2009, Martin Langhoff wrote:

> On Wed, Aug 12, 2009 at 10:43 AM, Benjamin M.
> Schwartz<bmschwar at fas.harvard.edu> wrote:
>> I don't know how to test this, but I think there's a chance it could be a
>> big win.  Of course, in situations where the mDNS presence information
>> itself is overloading the network, there's not much we can do.
>
> Get your hands on airtime.py -- and let's make sure everyone
> understands that in wireless networks
>
>   what really matters is _airtime_. Multicast frames are sent in the slowest
>   modulation available, and it consumes a ton of airtime. It doesn't take
>   much to swamp the RF.

I believe that the slowest modulation available is 1Mb/sec. so you would 
have to avoid something in the range of 30+ packets being sent before you 
have a chance of hitting break-even

David Lang