tricks of the trade

• Messages sorted by: [ date ][ thread ][ subject ][ author ]
• Next message: Jim Wiljanen: "Educational Networks in MI"
• Previous message: John D. Gravelle: "The Power to Change"

In the spirit of this week's questions I wanted to pass along some
techniques that we have been using in Pittsburgh to provide low-cost
service to local schools and community centers.  This work is part
of the Common Knowledge: Pittsburgh and Bridging the Urban Landscape
projects.  Pointers to further information can be found on the
Information Renaissance Web server,
	http://www.info-ren.org/what/what.php

1. HDSL.  This is a telephone technology that allows one to obtain very
high bidirectional data rates over conventional twisted pair copper
lines.  The majority of telcos now use this technology to reduce their
internal costs for the provision of T1 service.  To my knowledge these
cost savings have not yet been passed along to consumers, but they can
be substantial.  Using something called LADS lines (also known as dry
pairs in telco jargon), we have attached HDSL drivers at school sites
and our project's central site to obtain data rates ranging to 384,000
bits per second (1/4 T1) to 1,536,000 bits per second (full T1).  The
monthly cost for this setup is about $60, which is something like 1/10
the cost of a typical T1 line.  The down side to this technology is
that we have to maintain our own hardware, and the throughput is
dependent on line quality variables which are not under our control.
But it is a good indication of where technologies for a telco's copper
plant are heading.

2. Ethernet over cable TV.  Using the old coaxial plant in Pittsburgh
we have been able to establish 10 megabit per second shared bandwidth
connections between our project's central site and selected school and
community center sites.  Maintenance of the old plant seems inadequate
to keep these services going on a reliable basis, but communities with
newer fiber/coax hybrid plants could use this type of service quite
effectively.  The intrinsic cost of this type of service is low.  TCI's
@HOME service, for example, is being introduced in some communities at
$40 a month, and I believe this includes a comfortable profit margin
for the service provider.

3. ISDN in Speech Bearer Mode.  ISDN technology can provide 128,000
bits per second data service at low monthly costs - around $40 a month
in our area.  The catch is that most telcos charge very high time
charges for this type of service.  A trick that we have used is to
set up calls in speech bearer mode, since there are no time charges
for ISDN voice calls in our area.  The available bandwidth drops to
112,000 bits per second under this arrangement, and some brands of
ISDN routers don't support ISDN voice calls.  These caveats aside,
we have found the service to be quite reliable.

The techniques described above all have the potential to provide 
high-quality, low-cost connectivity for schools, libraries and homes.
There are, however, important regulatory issues associated with
each of them.

a- There is no meaningful competition for the provision of data
services in our region.  As a result, the cable company has not
deployed any fiber in the city of Pittsburgh, and the telephone company
does not encourage customers to use advanced technologies such as
HDSL.  If the cable company were selling data services with cable
modems on a new cable plant, the telephone company would probably
respond with HDSL-based services or something of equivalent economy and
reliability.  But in the absence of meaningful competition, both the
telephone company and the cable company are chasing after customers who
will pay premium prices for whatever services they buy.  Thus there is
a booming market in private fiber, but costs are very high.

b- Local regulation of the cable industry has resulted in fragmented
services.  While the city of Pittsburgh has no fiber from the local
cable provider, the surrounding county has lots of fiber, although
there is little in the way of new services on this fiber.  One suspects
that the cable companies find it easier to negotiate with the smaller
municipalities and are able to finance their investment in new physical
plant through rate increases in those municipalities.  In the meantime
other regions are starved out of services as part of the company's
negotiating tactics for a new franchise agreement.

c- Ambiguities in tariffs are sometimes used to frighten customers away 
from economical services.  The new residential ISDN tariff for our region 
contains an explicit prohibition on the use of ISDN voice calls for the 
transmission of data.  This is an unenforceable provision, since ISDN 
voice calls and ISDN data calls are both streams of digital data.  It's 
unclear to me why the state PUC allowed language of this sort, but it's 
clear that the intent is to discourage imaginative use of available services.

d- New competitors are likely to change the way in which old monopolies 
respond to new technology.  One case in point is the availability of HDSL 
technology.  Once there is unbundled access to copper in the local loop 
(the wires from the telephone company's central office to a customer's 
premises), then anyone will be able to sell services like HDSL over this 
plant.  Another example is Centrex ISDN.  Presently one can make untimed 
ISDN calls within a single Centrex, meaning that if you have several 
sites served by the same central office, you can make untimed calls 
between sites.  But the whole landscape of telco central offices is an 
artifact of an ancient copper infrastructure.  New competitors in the 
telephone business don't have multiple central offices;  they have a 
single regional switching point with fiber running across the region to 
reach their customers.  These new competitors can therefore offer Centrex 
ISDN across an entire county (and beyond).  Once this happens the 
traditional telcos will petition state PUCs to allow them to extend their 
ISDN calling areas to a similarly large region.  From the viewpoint of 
schools and libraries, it would be desirable for the state PUCs and the 
FCC to anticipate technology shifts of this type and help them to happen 
sooner rather than later.  Otherwise schools and libraries will be 
saddled with expensive, obsolescent services for an unnecessary long 
period of time.

Bob Carlitz
Project Director
Common Knowledge: Pittsburgh

• Next message: Jim Wiljanen: "Educational Networks in MI"
• Previous message: John D. Gravelle: "The Power to Change"