DMS100
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The DMS-100 is a member of the
Digital Multiplex System Digital Multiplex System (DMS) is the name shared among several different telephony product lines from Nortel Networks for wireline and wireless operators. Among them are the DMS-1 (originally named the DMS-256) Rural/Urban digital loop carrier ...
(DMS) product line of
telephone exchange telephone exchange, telephone switch, or central office is a telecommunications system used in the public switched telephone network (PSTN) or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital syste ...
switches manufactured by Northern Telecom. Designed during the 1970s and released in 1979, it can control 100,000 telephone lines. The purpose of the DMS-100 Switch is to provide local service and connections to the
PSTN The public switched telephone network (PSTN) provides infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local teleph ...
public telephone network. It is designed to deliver services over subscribers'
telephone line A telephone line or telephone circuit (or just line or circuit industrywide) is a single-user circuit on a telephone communication system. It is designed to reproduce speech of a quality that is understandable. It is the physical wire or ot ...
s and trunks. It provides
plain old telephone service Plain old telephone service (POTS), or plain ordinary telephone system, is a retronym for voice-grade telephone service employing analog signal transmission over copper loops. POTS was the standard service offering from telephone companies from 1 ...
(POTS), mobility management for cellular phone systems, sophisticated business services such as
automatic call distribution An automated call distribution system, commonly known as automatic call distributor (ACD), is a telephony device that answers and distributes incoming calls to a specific group of terminals or agents within an organization. ACDs direct calls based ...
(ACD),
Integrated Services Digital Network Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Work ...
(ISDN), and Meridian Digital
Centrex Centrex is a portmanteau of central exchange, a kind of telephone exchange. It provides functions similar to a PBX, but is provisioned with equipment owned by, and located at, the telephone company premises. Centrex service was first installed ...
(MDC), formerly called Integrated Business Network (IBN). It also provides
Intelligent Network The Intelligent Network (IN) is the standard network architecture specified in the ITU-T Q.1200 series recommendations. It is intended for fixed as well as mobile telecom networks. It allows operators to differentiate themselves by providing v ...
functions (AIN, CS1-R, ETSI
INAP INAP stands for Intelligent Network Application Protocol or Intelligent Network Application Part. It is the signalling protocol used in Intelligent Networking (IN). It is part of the Signalling System No. 7 (SS7) protocol suite, typically layere ...
). It is used in countries throughout the world. There are also DMS-200 and DMS-250 variants for
tandem Tandem, or in tandem, is an arrangement in which a team of machines, animals or people are lined up one behind another, all facing in the same direction. The original use of the term in English was in ''tandem harness'', which is used for two ...
switches. Much of the hardware used in the DMS-100, with the possible exception of the line cards, is used in other members of the DMS family, including the DMS-200 toll switch.


Hardware

All power distribution is at -48 VDC (nominal), from which
DC to DC converter A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of electric power converter. Power levels range from very low (small batteries) ...
s on every shelf provide other necessary voltages.


Central Control Complex (CCC)

The Central Control Complex comprises the Central Processing Unit (CPU), Program Store (PS), Data Store (DS) and the Central Message Controller (CMC). The CPU contains two identical 16-bit processors running in hot standby mode. The original CPU core was referred to as the NT40 CPU and was implemented in approximately 250 discrete logic devices across several circuit boards running at 36 MHz. The NT40 core consisted mainly of the NT1X44 stack card, which provides some register and stack functions of the processor, the NT1X45 which contained the arithmetic and logic functions, the NT1X46 which provides more registers and the load-route read-only memory (ROM) and the NT1X47 timing and control card which provides the micro-cycle source and microstore decoding functions of the processor. The NT1X47 card also contained the 2-digit hexadecimal display to indicate test result codes and the condition of the core. The NT1X48 processor maintenance card contained a thumbwheel on the faceplate to enable various diagnostic tests of the CPU. A later modification of these same five circuit boards with faster pin-compatible discrete logic devices enabled the CPU to operate at 40 MHz allowing central offices to improve call throughput capacity by 10 percent. When the CPU is configured in dual hot standby mode, a mate exchange bus (MEB) between the two CPUs enables the state of one CPU to be continuously compared to that of the other CPU on a cycle by cycle basis. Any discrepancy between the two CPUs results in maintenance circuitry determining which CPU is at fault and activity to change to the same CPU. A Program Store is dedicated to each CPU and is a memory for the program instructions required by that CPU for processing calls, maintenance and for administrative tasks. The PS associated with the other CPU contains identical program instructions. A Data Store is dedicated with each CPU and contains dynamic information on a per-call basis, as well as customer data and office-specific settings. The other CPU is also associated with its own DS containing duplicate data. The Central Message Controller controls the flow of messages between the other units of the CCC and prioritizes them for the Network Message Controller (NMC) in the various Network Modules (NM), or the Input/Output Controller (IOC). Both CPUs have access to either CMC which share the message load to the Line Modules or peripherals. The original NT40 based CCC was replaced by the compatible DMS SuperNode in 1987.


DMS SuperNode

The DMS SuperNode Computing Module was first based on the Motorola
68020 The Motorola 68020 ("''sixty-eight-oh-twenty''", "''sixty-eight-oh-two-oh''" or "''six-eight-oh-two-oh''") is a 32-bit microprocessor from Motorola, released in 1984. A lower-cost version was also made available, known as the 68EC020. In keepi ...
Central Processing Unit (CPU) and then upgraded to the Motorola
68030 The Motorola 68030 ("''sixty-eight-oh-thirty''") is a 32-bit microprocessor in the Motorola 68000 family. It was released in 1987. The 68030 was the successor to the Motorola 68020, and was followed by the Motorola 68040. In keeping with gener ...
. In the early 1990s it was further upgraded to use the Motorola 88100 and 88110
Reduced Instruction Set Computing In computer engineering, a reduced instruction set computer (RISC) is a computer designed to simplify the individual instructions given to the computer to accomplish tasks. Compared to the instructions given to a complex instruction set compu ...
(RISC) CPUs. This RISC version of the SuperNode Computing Module was known as the BRISC (BNR Reduced Instruction Set Computing) CPU. With the BRISC CPU the DMS SuperNode had a processing capacity of 1,500,000 call attempts per hour. DMS SuperNode featured increased processing capacity across a distributed architecture allowing for the development of new features and services. Each of the elements of the DMS SuperNode uses a common SuperNode CPU hardware design differing only in the software used to control them. The SuperNode consists of two main elements: DMS Core and DMS Bus. DMS Core provides the main computing facility and is made up of the Compute Module, System Load Module and a Message Controller. The Compute Module contains redundant SuperNode CPUs to handle call processing and maintenance functions and, like the NT40 core, can operate in a synchronized mode with its mate. The System Load Module contains all the necessary software for every element of the DMS switch and also provides file system and data storage functions on magnetic tape and hard disk. The Message Controller provides communications links between the DMS Core and the DMS Bus. DMS Bus is used to interconnect the DMS Core, the switching network and the Input/Output controller (IOC) and manage message flows between these units and consists of redundant Message Switches. The Message Switches of the DMS Bus operate in a load-sharing mode and one of them provides the main clock source for the DMS-100 system while the others are synchronized to it. Messages between all SuperNode units are carried by optical DS512 links. The operating system used by both generations of the DMS-100 switch was called Support Operating System (SOS) and was written in a high level language called
PROTEL Protel stands for "Procedure Oriented Type Enforcing Language". It is a programming language created by Nortel Networks and used on telecommunications switching systems such as the DMS-100. Protel-2 is the object-oriented version of Protel.'. Its n ...
which stood for PRocedure Oriented Type Enforcing Language developed at Bell Northern Research (BNR). Hardware and maintenance are administered locally through cathode-ray terminals, through a multilevel menu system called MAPCI. There are various methods used to access the DMS remotely as well, including modem and telnet. Backups and other hard drive work are administered through a DISKUT command line program.


Line Module

Analog lines are terminated on individual
line card A line card or digital line card is a modular electronic circuit designed to fit on a separate printed circuit board (PCB) and interface with a telecommunications access network. A line card typically interfaces the twisted pair cable of a plain ...
s, each with its own
codec A codec is a device or computer program that encodes or decodes a data stream or signal. ''Codec'' is a portmanteau of coder/decoder. In electronic communications, an endec is a device that acts as both an encoder and a decoder on a signal or ...
, in pull-out Line Drawers in frames. The original design of such frames was called the Line Module (LM) with 32 lines per drawer. LMs were not able to send
caller-id Caller identification (Caller ID) is a telephone service, available in analog and digital telephone systems, including voice over IP (VoIP), that transmits a caller's telephone number to the called party's telephone equipment when the call is ...
information (CLASS services) and became rare late in the century, having been supplemented or replaced by the newer Line Concentrating Module (LCM). Duplicated ringing generators serve each LM or pair of LCM. For DC testing, each line card has a relay to connect it to a test bus.


Line Concentrating Module

LCM have smaller line cards, serving 64 lines per physical drawer (2 logical drawers) of the same size as in the LM. An LCM require only half the space as an LM for the same number of lines. The majority of line cards are NT6X17, with three relays for loop start lines. Others include NT6X18 which have four or more relays and a slide switch for ground start lines (a newer version of the NT6X18 has eliminated the ground switch). The NT6X18 also has the ability to provide current reversal required for some coin phones and business systems. The NT6X17BA and the NT6X18BA is known as the world line card and is software configurable to more than 15 million functional settings to meet almost any signalling and transmission requirement in any market. NT6X19 line card allows the use of older style, neon message-waiting lamps, this feature also requires an addition card per drawer that supplies the voltage. Type NT6X21 cards serve P-sets (Meridian Business Sets), a special analogue telephone with a proprietary Nortel
data link A data link is the means of connecting one location to another for the purpose of transmitting and receiving digital information (data communication). It can also refer to a set of electronics assemblies, consisting of a transmitter and a recei ...
operating at 8 kHz to provide advanced call handling services. For example, a telephone number may appear on multiple P-sets even though each such telephone has only one pair of wires, thus providing a simpler replacement for
key telephone system A business telephone system is a multiline telephone system typically used in business environments, encompassing systems ranging in technology from the key telephone system (KTS) to the private branch exchange (PBX). A business telephone syst ...
s. An LCME, for ISDN service, which uses NTBX27 cards serve Basic Rate ISDN lines. When provided with ring generators, an LCME can also support other linecard types. LCMs are served by a Line Group Controller (LGC) and communicate over DS-30 connections to NT6X48AA interface cards on the LGC. The number of LCMs per LGC depends on traffic: 3-4 LCM per LGC but as few as two where traffic is heavy.


Remote Cluster Controller

Remote offices, anywhere from a kilometre to 100 km from the host, can be served by a Remote Line control Module (RLCM), Remote Switching Center (RSC); a later vintage is known as RCC2. They use T1 links to the host LGC. RCCs/RCC2s work like LGCs in controlling LCMs. Large remotes may have 2+ RCC/RCCs and they can be equipped with links between the RCCs - Interlinks; so calls within the remote do not tie up host links. The RCCs/RCC2s are usually equipped so they will provide calling within the remote office if the host links fail; this feature is called ESA; Emergency Stand Alone.


Remote Units

Another type of remote office is known as Remote Carrier Urban (RCU). Such units typically reside on the side of a road in a large box, approx 3 meters across, almost 2 meters high and almost a meter through. In the 1980s many telcos installed an early version of these instead of pulling more cable into a remote area. They were much cheaper and could provide up to approx 500 lines. Back then they needed two 'boxes' to work- a host box called a Central Terminal (CT) that had the dial tone lines wired into it and a remote box called a Remote terminal (RT) where the dial tone 'came out'. They used 2-6 T1 links on copper - i.e. LD-1 or fiber. As Telcos modernized, these same remote boxes were re-configured to work directly from a SMU peripheral at the host DMS. Typically each SMU can handle 3-6 RCUs.


Trunk Modules

Transmitters, receivers and other service circuits are in Trunk Module (TM) and Miscellaneous Trunk Module (MTM) shelves. Trunks are on DTC (Digital Trunk Controller) or DTCI (Digital Trunk Controller ISDN) or PDTC (PCM30 Digital Trunk Controller) shelves, usually two T-1 lines per card, ten cards per DTC for a total of 480 ds0 voice channels. At the turn of the century many original NT6X50AA cards were still in service that cannot perform T-carrier
extended superframe In telecommunications, superframe (SF) is a T1 framing standard. In the 1970s it replaced the original T1/D1 framing scheme of the 1960s in which the framing bit simply alternated between 0 and 1. Superframe is sometimes called D4 Framing to a ...
signaling, this can be performed with a plug-in replacement NT6X50AB card, used for services such as PBX ISDN T1s. Trunks can also be provisioned on SPM (Synchronus Peripheral Module) capable of handling 2016 DS0s, nearly 4.2x more than the DTC.


Line Controllers

Internal connections to the time switch (network) are on 2.56 Mbit/s (DS-30) Speech Links, each carrying thirty channels plus synchronization and data channels, on four wires plus a ground wire. Connections to the network are handled by the NT6X40AA DS-30 interface card on an LGC or LTC and these link may also be DS-512 optical interfaces. Using the NT6X44AA time switch card, LGCs and LTCs internally map channels on the NT6X48AA DS-30 & NT6X50AA/AB DS1 interface links to available channels on NT6X40AA DS-30 or NT6X40FA DS-512 interfaces out to the network. European PDTCs were complemented by the DTCOI2 and DTCO2. The DTCOI2 was designed to run PRI and DPNSS services as per existing PDTCOI and MSB7 peripherals. The DTCO2 was designed to carry CAS and SS7 as per existing PDTCO peripheral. Time Division switching is performed in E-Net, similar to the Communication Module of 5ESS switch or the Switching Network of EWSD or the Group Switch of
AXE telephone exchange The AXE telephone exchange is a product line of circuit switched digital telephone exchanges manufactured by Ericsson, a Swedish telecom company. It was developed in 1974 by Ellemtel, a research and development subsidiary of Ericsson and Tele ...
.


Successors

There are also DMS-200 and DMS-250 variants for
tandem Tandem, or in tandem, is an arrangement in which a team of machines, animals or people are lined up one behind another, all facing in the same direction. The original use of the term in English was in ''tandem harness'', which is used for two ...
switches. In 2006 Nortel introduced the Communication Server 1500 (CS 1500) Softswitch based on VOIP to modernize the DMS-based telephone switches. A CS 1500 softswitch system can replace all the DMS component modules except for the LCMs, reducing the footprint of a DMS-100 to one 19" rack and allowing operators to reduce cooling and power requirements significantly. A successor to the DMS-100 is the Communication Server 2000 (CS2K), which shares many components and software with the DMS. The significant difference is the addition of
VOIP Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet t ...
technology into the CS2K. In 2010,
Genband Ribbon Communications US LLC is a public company that makes software, IP and optical networking solutions for service providers, enterprises and critical infrastructure sectors. The company was formed in 2017, following the merger of Genband and ...
purchased Nortel Networks' Carrier VoIP and Application Solutions (CVAS) business for $182.5 million.
Nortel Nortel Networks Corporation (Nortel), formerly Northern Telecom Limited, was a Canadian multinational telecommunications and data networking equipment manufacturer headquartered in Ottawa, Ontario, Canada. It was founded in Montreal, Quebec, ...
is now defunct.


See also

*
List of telephone switches This list of telephone switches is a compilation of telephone switches used in the public switched telephone network (PSTN) or in large enterprises. American Digital Switching * Centura 2000 Alcatel This lists Alcatel switches before the merger ...


References


External links


DMS-100
at the
Nortel Networks Nortel Networks Corporation (Nortel), formerly Northern Telecom Limited, was a Canadian multinational telecommunications and data networking equipment manufacturer headquartered in Ottawa, Ontario, Canada. It was founded in Montreal, Queb ...
website {{DEFAULTSORT:Dms-100 Multiplexing Telephone exchange equipment Nortel products