[opendtv] Last mile connections
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 22 Jul 2014 22:51:24 +0000
Craig Birkmaier wrote:
> DSL is dependent on upstream congestion; all I was saying is that the
> "last mile" link to the customer is not the problem, as it is dedicated.
> The problem for DSL is that it is too slow.
Craig, the cable company can make that last mile more and more "dedicated" as
well, as it effectively has been doing bit by bit. Both the telcos and the
cablecos are having to change their plants in neighborhoods.
As you move beyond ADSL, you are also reducing the maximum length of the
twisted pair xDSL link. So for example, VDSL can provide a very decent 52 Mb/s,
but it cannot be more than 300 meters of copper twisted pair for that speed.
Way less than a mile. SIMILARLY, a cable company can change the headends of its
passive plants to provide even way more than 50 Mb/s, to its customers, if it
chooses to. In both cases, the telco or cableco can make these improvements
without visiting homes, but it would have to get into neighborhoods.
Remember when cable was all hot about "switched TV" channels, where you'd
select the channel and an upstream cable device would send just that channel?
Well, the cableco can do that, stop sending the continuous hundreds of TV
broadcast channels downstream on each coax, and dedicate much more cable
bandwidth to DOCSIS instead.
The difference of course is that the cable company can take this a lot further
than the telco can, because they already have *coax* to homes.
> The telcos can deploy the necessary equipment at the CO and at upstream
> interconnection hubs to eliminate congestion. And they can offer
> co-location space for edge servers.
Yes, and so can the cable companies.
> I would point out that the local loops for cable are NOT passive. They
> are a shared resource and available bandwidth can fluctuate based on
> demand.
Passive means that they have a head-end from which the fiber and coax plants
are then passively split. They do not deploy active boxes, like Ethernet
switches, in those boxes on people's lawns. But, after you've maxed out the
modulation, how many homes each passive plant serves has to go down, if you
want to give more capacity to each home.
> For DSL and cable the customer can do the installation. For FIOS the
> telco must connect to the premises and install the termination
> equipment.
Which is why it's more difficult for FiOS! That was my point. Verizon is not
improving its xDSL in places where FiOS is available. That's what's costing
them a bundle!
Bert
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- » [opendtv] Last mile connections - Manfredi, Albert E