Mike, All,
What do you think about the direction this firm (TranSwitch) is taking in this release? I could almost _hear_ the indigestion that this one is causing in some circles. Preserve the visibility of the 64 kbps DS0? <grin>
Regards, Frank C.
=================
Returning to its Sonet roots, TranSwitch updates devices
July 28, 1998
ELECTRONIC ENGINEERING TIMES via NewsEdge
Corporation : Shelton, Conn. - TranSwitch Corp., the
telecom IC company that was weaned on Sonet before
expanding into asynchronous transfer mode (ATM), is
returning to a new generation of Sonet multiplexers and
cross-connects with a revised vision of the architectures
required. As Sonet picks up steam as an Internet access
technology, TranSwitch is keeping a strong hand in
framer devices for pleisochronous digital hierarchy
(PDH) services, while assuming that PDH networks must
coexist with SDH/Sonet broadband systems.
After releasing a quartet of WAN products in June,
including an advanced mapper and multiple-service
framers, TranSwitch's next step is to roll out a 3.3-V
overhead termination device called PHAST-1 this week.
It will be followed by a dedicated HDLC controller in the
autumn.
For TranSwitch, functions like overhead termination and
HDLC-based serial control are moving to the forefront.
So are embedded RISC cores and increasing overall
integration of digital devices, in an effort to combine
elements of overhead processing, service mapping and
Sonet payload envelope processing.
Last summer, TranSwitch brought in Deepak Rana, an
executive with experience at Bell Labs and IBM, as
Sonet/ SDH product marketing manager, to reformulate
its silicon strategy for high-layer processing in
next-generation Sonet designs. While physical-layer
specialists may concentrate on very high-speed
backbones, Rana said it was equally important for the
digital logic devices used in Sonet transmission systems
to preserve the visibility of DS-0 (64-kbit/second) data
streams.
On the surface, a design strategy that de-emphasizes
simple single-channel framers may seem incongruous,
given the fact that TranSwitch included three new
framers among the four Sonet products introduced at the
June Supercomm show.
But Rana pointed out that advanced framer architectures
support new types of feature sets, tailored for
byte-synchronous and asynchronous services.
The DS1MX7 seven-channel mapper was a critical chip
for bringing together PDH and SDH worlds, Rana said.
When used in a Sonet terminal multiplexer, it can link to a
line-interface unit in a byte-synchronous mode using
quad T1 framers, or directly in asynch mode. It can also
connect to multiple DS-0 64-kbit services in a byte-synch
mode-all within one system from a common mapping
device.
But TranSwitch is finding a secondary use for the
DS1MX7 as a byte-synch frame-relay Internet access
system for customer premises use. Here, the mapper
links directly to the PHAST-1 chip that will be
introduced this week for add-drop termination, and to a
multichannel HDLC device for direct connections to
local buses.
The PHAST-1 is an example of the need for lower power
dissipation and greater feature sets even at the lower
Sonet speeds, such as STS-1 (51 Mbits/s). The device is
intended to simultaneously provide section, line and
path termination, along with alarm detection and
generation. An on-chip RAM stores overhead bytes.
The move to multiple-channel HDLC will be a new one
for TranSwitch. Rana said the company is not ready to
provide full details on the device yet, except to say that
it will make use of programmable RISC cores. TranSwitch
has experience in its own microprogrammed engine
through the SARA and SARA Lite, used for ATM
segmentation and reassembly. The HDLC processor,
however, will be based on a standard MIPS instruction
set.
No surprises
The beauty of the mix-and-match approach across PDH
and SDH worlds, Rana said, is that TranSwitch does not
have to be caught by surprise as systems emerge that
combine processing layers, such as packet over Sonet or
ATM cells over optical WDM (wavelength-division
multiplexing) layers. As Sonet moves into the Internet
service-provider market, Rana said, "it's a misnomer to
call it a transmission system any more. It's an Internet
access system."
The only thing that is off the table in current planning,
Rana said, is to divorce design concepts from silicon by
moving to an intellectual-property approach of the sort
adopted by newcomers like Cimaron Communications
Inc. (Andover, Mass.).
"People always ask us to provide them with soft macros,
and in almost all circumstances we say no," Rana said.
"No matter how I look at the market dynamics, providing
an intellectual-property core for higher-layer Sonet
functions makes zero sense."
Copyright - 1998 CMP Media Inc.
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