Analogue Private Circuits
BT strongly believes that next
generation network (NGN) technology offers new and exciting solutions
for the breadth of our portfolio, including data products that have
traditionally been served by Time Division Multiplexing TDM/Synchronous
Digital Hierarchy (SDH) technology.
BT
recognises that some customers have applications that rely on certain
characteristics of current TDM data services. BT respects these
requirements and intends products that use 21CN, wholly or in part, to
meet them as far as is technically and commercially practicable. Hence
BT's 21CN is being built on an infrastructure that supports both
innovative packet-switched NGN products as well as more traditional
non-deterministic SDH based products. At a minimum, BT is committed to
continuing to provide the appropriate set of products that meet all
relevant international standards for TDM data transmission, most
particularly ETSI G.703.
We
currently plan to meet this commitment by providing TDM data services
(including sub-2Mbps) on our existing legacy network platforms or the
SDH infrastructure of 21CN where obsolescence in elements of the
existing legacy networks necessitates it.
We
will continue to review the state of progress with our customers,
including the practicalities of migration, before any long-term network
design decisions with respect to these products and services are
finalised. In any event, we have decided to extend the provision of
service on our existing network from 2011 until at least Q1 2014 for
all TDM circuits, including those under 2Mbps, provided there is
sufficient customer demand to do so.
2007 TDM consultation exercise
BT
conducted a feasibility study in 2007 on the strategy to provide
Analogue Private Circuits on their 21st Century Network that addressed
the following three analogue service categories:.
Analogue service falls into three categories:
- Copper own exchange
- A and B end of circuit are fed from the same exchange.
- Copper different exchange
- The
A end of circuit is on one exchange, the B end is on a different
exchange and the connection between them is copper and could be
amplified.
- Analogue over digital
- A and B ends
are fed from different exchanges and the connection between the
exchanges uses the Digital Private Circuit Network (DPCN).
Each
of these products provides different challenges and will require
different solutions on 21CN. The current view is that the “copper own
exchange” service will remain unaffected but that the “copper different
exchange” and “analogue over digital” circuits will require some
additional planning to migrate to 21CN.
The analogue
feasibility study focused on reviewing the options for replacing the
functionality of the existing platforms, assessing the manpower
required for continued maintenance and the future availability of the
necessary hardware
The results of this feasibility study were fed
into BT’s Consult21 industry consultation on the future of TDM products
which closed on 31 January 2008. This consultation focused specifically
on the future of Partial Private Circuits (PPCs) rather than retail
Leased Lines – however, the two are interconnected as service providers
typically build retail Leased Lines using PPCs. Service providers had
the opportunity to meet with BT and discuss these proposals and a
number provided their comments by the end of the consultation period on
30 November 2007. The Energy Networks Association (ENA) also provided
BT with a combined set of comments from utility companies.
The
outcome of the consultation and the subsequent studies that followed as
a result of feedback from customers and industry, as well as the
implications for products and services will be published in due course.