More Technical info on the Nortel DMS-250, gathered by Mark Morris.
Product Technical Overview
DMS-250 hardware platform
The DMS-250 hardware architecture includes fully integrated processing components to perform the following operations:
Central processing in the DMS-Core
Messaging over the DMS-Bus
Switching in the Enhanced Network (ENET)
Trunk interfaces to other switching systems
Maintenance and billing through an Input/Output Controller
Multicomputing platform for CCS7 and advanced data processing applications
Central Processing
The DMS-Core is the central processing unit (CPU) and memory of the system, handling high-level call processing, system control functions,
system maintenance, and the installation of new switch software. At the center of the DMS-Core design strategy is the use of commercially
available microprocessors, allowing it to evolve and incorporate the latest advances in processing technology as they are introduced. In
addition, because the DMS-Core accommodates a range of microprocessors, the DMS-250 system is available with different levels of
DMS-Core processing power, enabling long distance carriers to increase processing power as needed.
The DMS-Core is fully duplicated. Both planes of the DMS-Core are simultaneously processing each call, allowing the standby plane to
immediately take over the call processing-with no loss of service - if the primary plane should fail.
Messaging
The high-speed DMS-Bus is the "traffic cop" of the DMS-250 system, a data bus connecting the various computing elements and enabling
peer-to-peer communications among components of the switch. Most importantly, the DMS-Bus is the key design element that allows the
DMS-250 system to be a true multi-computing platform, onto which peripheral processors such as the LPP can be added to grow both the
capacity and the service portfolio of the system. For the minimum DMS-250 system, the DMS-Bus is provisioned with 16 megabytes of
memory in the Message Switch.
Switching in the Enhanced Network (ENET)
The DMS-250 switching matrix, the ENET, switches calls to their destinations. The ENET uses the latest technology in chip design and
system packaging to support both today's services-like voice and narrowband data-and a range of future services. For small applications, a
single-shelf ENET can be provisioned, expandable up to four shelves. The ENET infrastructure is housed in a standard DMS SuperNode
cabinet, with all the benefits this packaging offers in protection from electromagnetic interference, electrostatic discharge, and Zone 4
earthquake forces.
ENET dramatically reduces the number of cables required to connect network modules, provides greater reliability, and demands less
engineering and maintenance attention than traditional junctor systems. Fiber-optic links provide additional flexibility, reliability, and system
performance. A key advantage of ENET is its simple, straightforward engineering. Unconstrained by traffic and load balancing issues,
provisioning is based only on peripheral-link terminations.
Trunk Interfaces
Peripheral modules form a bridge between the DMS-250 switching matrix and the trunks and lines it serves, handling voice and data traffic
to and from customers (in the case of Dedicated Access Lines) other switching systems. All peripheral modules must have XPM PLUS,
which offers almost twice the memory of earlier hardware and more realtime capacity (20% to 30% for three-processor peripheral modules
and 60% to 65% for two-processor peripheral modules). Four to five circuit packs combine into one for better space utilization, reduced
power requirements, and improved reliability.
Maintenance and Billing
Through an integral maintenance and billing subsystem, the DMS-250 facilitates billing and various OAM (operations, administration, and
maintenance) activities that are crucial to the cost-effective management of a carrier switching environment. The system also keeps records
of calls and makes the information available to bill-processing systems. Maintenance and billing devices either reside in or are connected to
an Input/Output Equipment frame.
Multicomputing Platform
To allow carriers to capitalize on their most powerful resource-the DMS-250 switch-the architecture is designed around a distributed
processing strategy that allows many processing tasks to be shared among various application and peripheral processors. System peripheral
modules, for example, relieve the DMS-Core computing module from the overhead of many routine tasks. This distributed processing
architecture allows network providers to incrementally add processing elements to their system.
The Link Peripheral Processor (LPP) for example, is central to many long distance applications in that it handles much of the processing
functions of CCS7 networking. |
