Re: symmetric vs. asymmetric [was: Verizon Policy Statement on Net Neutrality]

[Scott Helms <khelms () zcorum com>]

Stephen is dead on here.  In DOCSIS the downstream communication happens in
one or more normal cable TV channel band, ie 6MHz channels from 54 MHz to
890MHz.  The upstreams will be (in most cases) either 1.6 MHz, 3.2 MHz, or
6.4MHz wide and in the 5-42 MHz range.


Scott Helms
Vice President of Technology
ZCorum
(678) 507-5000
--------------------------------
http://twitter.com/kscotthelms
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On Fri, Feb 27, 2015 at 4:56 PM, Stephen Satchell <list () satchell net> wrote:

> On 02/27/2015 01:27 PM, Jack Bates wrote:
> > My 2 cents. I don't design these things, but you'd think people would
> > start realizing that static allocation is kind of limiting. Giving
> > someone 50mb/s with 20mb/s waste is annoying when they are saturating
> > 3mb/s the opposite direction. Wouldn't it be cool if your backup at
> > night could use 50mb/s upstream and drop your downstream to 5mb/s
> > because you aren't downloading anything?
>
> That's possible with multicarrier technology, such as xDSL.  When you
> get into the data-over-cable technology, you find a completely different
> story -- it's a system limitation that you have an upstream channel that
> is less efficient than the downstream channel because the upstream
> channel has to be accessed by a number of sources, with access control,
> whereas the downstream channel is nothing more than a broadcast pipe
> (just like 10base-2 Ethernet) where you pick your packets out of the
> stream.
>
> Other technologies have their quirks, too...