543 lines
22 KiB
Plaintext
543 lines
22 KiB
Plaintext
==Phrack Inc.==
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Volume Four, Issue Forty-One, File 7 of 13
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How To Build A DMS-10 Switch
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by The Cavalier
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Society for the Freedom of Information
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March 11, 1992
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With the telephone network's complexity growing exponentially as the
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decades roll by, it is more important than ever for the telecom enthusiast to
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understand the capabilities and function of a typical Central Office (CO)
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switch. This text file (condensed from several hundred pages of Northern
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Telecom documentation) describes the features and workings of the Digital
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Multiplex Switch (DMS)-10 digital network switch, and with more than an average
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amount of imagination, you could possibly build your own.
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The DMS-10 switch is the "little brother" of the DMS-100 switch, and the
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main difference between the two is the line capacity. The DMS line is in
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direct competition to AT&T's ESS line (for the experienced folks, the features
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covered are the as those included in the NT Software Generic Release 405.20 for
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the 400 Series DMS-10 switch).
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Table of Contents
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~~~~~~~~~~~~~~~~~
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I. OVERVIEW/CPU HARDWARE SPECS
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II. NETWORK SPECS
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1. Network Hardware
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2. Network Software
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3. Advanced Network Services
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III. EXTERNAL EQUIPMENT SPECS
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1. Billing Hardware
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2. Recorded Announcement Units
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3. Other Misc. Hardware
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IV. MAINTENANCE AND ADMINISTRATION
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1. OAM
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2. Interactive Overlay Software Guide
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V. SPEC SHEET
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VI. LIMITED GLOSSARY
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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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I. OVERVIEW/CPU HARDWARE SPECS
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Overview
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The DMS-10 switch is capable of handling up to 10,800 lines, and was
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designed for suburban business centers, office parks, and rural areas. It can
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be installed into a cluster configuration to centralize maintenance and
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administration procedures and to increase combined line capacity to 50,000
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lines. It is capable of functioning as an End Office (EO), an Equal Access End
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Office (EAEO), and an Access Tandem (AT), and is a known as a Class 5 switch.
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It supports up to 3,408 trunks and 16,000 directory numbers. It can outpulse
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in DP (Dial Pulse), MF (Multi-Frequency), or DTMF (Dual-Tone Multi-Frequency),
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insuring compatibility with new and old switches alike (translation -- the
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switch is small, by most standards, but it has massive bounce for the ounce).
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Hardware Specifications
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The DMS-10 switch itself is a 680x0-based computer with 1 MB of RAM in its
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default configuration. The processor and memory are both duplicated; the
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backup processor remains in warm standby. The memory system is known as the
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n+1 system, meaning that the memory is totally duplicated.
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II. NETWORK SPECS
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Network Hardware
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The DMS-10 network hardware consists mostly of PEs, or Peripheral
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Equipment trunk and line packs. The PEs take the incoming analog voice
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signals, digitalize them into 8 bit PCM (Pulse Code Modulation) signals, and
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feed it into the main transmission matrix section of the switch. There, it is
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routed to another trunk or line and converted back into an analog signal for
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retransmission over the other side of the call. Note that manipulating voice
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in the digital domain allows the signal to be rerouted, monitored, or
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retransmitted across the country without any reduction in signal quality as
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long as the signals remain in PCM format. <Hint!>
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Network Software
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The DMS-10 has a variety of software available to meet many customers'
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switching needs. A good example of this software is the ability of several
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DMS-10 switches to be set up in a cluster (or star configuration, for those of
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you familiar with network topologies). In this arrangement, one DMS-10 is set
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up as the HSO (Host Switching Office) and up to 16 DMS-10s are set up as SSOs
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(Satellite Switching Offices), allowing all billing, maintenance, and
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administration to be handled from the HSO. Additionally, all satellites can
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function on their own if disconnected from the HSO.
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Another feature of the DMS-10's network software are nailed-up
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connections, commonly known as loops. The DMS-10 supports up to 48 loops
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between any two points. The connections are constantly monitored by the switch
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computer, and if any are interrupted, they are re-established.
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Meridian Digital Centrex (MDC) is the name given to a group of features
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that enable businesses to enjoy the benefits of having PBX (Private Branch
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Exchange) equipment by simply making a phone call to the local telco.
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Advanced Network Services (ANS)
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If the DMS-10 is upgraded with the 400E 32-bit RISC processor, the switch
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will be able to handle 12,000 lines, enjoy a speed improvement of 80%, support
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a six-fold increase in memory capacity, and, perhaps most importantly, will be
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able to run NT's Advanced Network Services software. This software includes
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Common Channel Signaling 7 (CCS7), Advanced Meridian Digital Centrex, DMS
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SuperNode connectivity, and ISDN. CCS7 is the interswitch signaling protocol
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for Signaling System 7, and the concept deserves another text file entirely
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(see the New Fone eXpress/NFX articles on SS7).
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III. EXTERNAL EQUIPMENT SPECS
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Billing Format Specifications
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The DMS-10 can record AMA (Automatic Message Accounting) billing data in
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either Bellcore or Northern Telecom format, and it can save this data in one of
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several ways:
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- by saving onto a 9-track 800 BPI (Bits-Per-Inch) density tape drive
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called an MTU (Magnetic Tape Unit)
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- by saving onto a IOI (Input/Output Interface) pack with a 64 MB SCSI
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(Small Computer System Interface) hard drive, and transferring to 1600
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BPI tape drives for periodic transport to the RAO (Regional Accounting
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Office)
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- by transmitting the data through dial-up or dedicated telephone lines
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with the Cook BMC (Billing Media Converter) II, a hard drive system that
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will transmit the billing records on request directly to the RAO. The
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Cook BMC II supports six different types of transmission formats, listed
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below:
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* AMATS (BOC) [max speed: 9600 bps]
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Call records are stored using the Bellcore AMA format and polled
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using the BX.25 protocol. Two polling ports are provided with one
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functioning as a backup.
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* BIP Compatible [max speed: 9600 bps (2400*4)]
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Call records are stored using the Bellcore AMA format and polled
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using the HDLC Lap B protocol. Four polling ports are provided
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that can function simultaneously for a combined throughput of 9600
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bps. This specification is compatible with GTE's Billing
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Intermediate Processor.
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* Bellcore AMA w/ BiSync polling [max speed: 9600 bps]
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Call records are stored using the Bellcore AMA format and polled
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using the IBM BiSync 3780 protocol. One polling port is provided.
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This option is intended for operating companies who use independent
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data centers or public domain protocols for data processing.
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* Bellcore AMA w/ HDLC polling [max speed: 9600 bps]
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Call records are stored using the Bellcore AMA format and polled
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using the HDLC (High-level Data Link Control) protocol. One port
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is provided.
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* NT AMA w/ HDLC polling [max speed: 9600 bps]
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Call records are stored using the Northern Telecom AMA format and
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polled using the HDLC protocol.
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* NT AMA w/ BiSync polling [max speed: 4800 bps]
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Call records are stored using the Northern Telecom AMA format and
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polled using the BiSync protocol.
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- by interfacing with AT&T's AMATS (Automatic Message Accounting
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Teleprocessing System)
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- by interfacing with the Telesciences PDU-20
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All of the above storage-based systems are fully fault-tolerant, and the
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polled systems can store already-polled data for re-polling.
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Recorded Announcement Units
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The DMS-10 system may be interfaced to one or more recorded announcement
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units through two-wire E&M trunks. Some units supported include the Northern
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Telecom integrated Digital Recorded Announcement Printed Circuit Pack (DRA
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PCP), the Cook Digital Announcer or the Audichron IIS System 2E.
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The DRA PCP is integrated with the DMS-10 system, as opposed to the Cook
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and Audichron units, which are external to the switch itself. It provides
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recorded announcements on a plug-in basis and offers the following features:
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- Four ports for subscriber access to announcements
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- Immediate connection when pack is idle
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- Ringback tone when busy until a port is free
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- Switch-selectable message lengths (up to 16 seconds)
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- Local and remote access available for message recording
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- Memory can be optionally battery-backed in case of power loss
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- No MDF (Main Distribution Frame) wiring required
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Other External Hardware
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The DMS-10 can also support the Tellabs 292 Emergency Reporting System,
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the NT Model 3703 Local Test Cabinet, and the NT FMT-150 fiber optic
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transmission system. More on this stuff later, perhaps.
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IV. MAINTENANCE AND ADMINISTRATION
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OAM
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---
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OAM, or Operations, Administration, and Maintenance functions, are
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performed through an on-site maintenance terminal or through a remote
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maintenance dial-in connection. The DMS-10 communicates at speeds ranging from
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110 to 9600 baud through the RS-232C port (standard) in ASCII. There can be up
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to 16 connections or terminals for maintenance, and security classes may be
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assigned to different terminals, so that the terminal can only access the
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programs that are necessary for that person's job. The terminals are also
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password protected, and bad password attempts result in denied access, user
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castration and the detonation of three megatons of on-site TNT. <Just kidding>
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The software model for the DMS-10 consists of a core program which loads
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overlays for separate management functions. These overlays can be one of two
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types: either free-running, which are roughly analogous to daemons on Unix
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environments, which are scheduled automatically; or interactive, which
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communicate directly with the terminal user.
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The major free-running programs are the Control Equipment Diagnostic
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(CED), the Network Equipment Diagnostic (NED), the Peripheral Equipment
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Diagnostic (PED), and the Digital Equipment Diagnostic (DED). The CED runs
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once every 24 hours, and tests the equipment associated with the CPU buses and
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the backup CPU. The NED runs whenever it feels like it and scans for faults in
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the network and proceeds to deal with them, usually by switching to backup
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hardware and initiating alarm sequences. The PED is scheduled when the switch
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is installed to run whenever the telco wants it to, and it systematically tests
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every single trunk and line connected to that central office (CO). The DED
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tests the incoming line equipment that converts analog voice to digital PCM.
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Now, for interactive programs (a.k.a. interactive overlays), I'm going to
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list all of their codes, just in case one of you gets lucky out there. To
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switch to an overlay, type OVLY <overlay>. To switch to a sub-overlay, type
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CHG <sub-overlay>. Keep in mind that NT has also installed help systems on
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some of their software, accessible by pressing "?" at prompts. Here we go:
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Overlay Explanation and Prompting Sequences
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------- -----------------------------------
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ALRM Alarms
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ALPT - Alarm scan points
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SDPT - Signal distribution points
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AMA Automatic Message Accounting
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AMA - Automatic Message Accounting
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MRTI - Message-rate treatment index
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PULS - Message-rate pulsing table
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TARE - Tariff table
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AREA Area
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CO - Central Office Code
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HNPA - Home Numbering Plan Area
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RC - Rate Center
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RTP - Rate Treatment Package
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CLI Calling Line Identification
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CNFG Configuration Record
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ALRM - Alarm System Parameters
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AMA - Automatic Message Accounting parameters
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BUFF - System Buffers
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CCS - Custom Calling Services
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CCS7 - Common Channel Signaling No. 7
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CDIG - Circle Digit Translation
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CE - Common Equipment Data
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CLUS - Cluster data
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COTM - Central Office overload call timing
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CP - Call processing parameters
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CROT - Centralized Automatic Reporting of Trunks
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CRTM - Central Office regular call processing timing
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CSUS - Centralized Automatic Message Accounting suspension
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DLC - Data Link Controller assignment for clusters
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E800 - Enhanced 800 Service
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FEAT - Features
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GCON - Generic Conditions
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HMCL - Host message class assignment
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IOI - Secondary input/output interface pack(s)
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IOSF - Input/Output Shelf Assignment
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LCDR - Local Call Detail Recording
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LIT - Line Insulation Testing parameters
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LOGU - Logical Units Assignments
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MOVE - Move Remote Line Concentrating Module
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MTCE - Maintenance Parameters
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MTU - Magnetic Tape Unit Parameters
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OPSM - Operational Measurements
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OVLY - Overlay scheduling
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PSWD - Password Access
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SITE - Site assignments
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SSO - Satellite Switching Office Assignments
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SUB - Sub Switch
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SYS - System parameters
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TRB - Periodic trouble status reporting
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VERS - Version
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CPK Circuit Pack
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ACT - AC Testing Definition
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DCM - Digital Carrier Module
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LPK - Line Concentrating Equipment line packs
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PACK - Peripheral Equipment packs
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PMS - Peripheral Maintenance System pack
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PSHF - Peripheral Equipment Shelf
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RMM - Remote Maintenance Module
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RMPK - Remote shelf
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RSHF - Remote Concentration Line Shelf
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SBLN - Standby line
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SLC - SLC-96
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SLPK - SLC-96 pack
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DN Directory Number
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ACDN - Access Directory Number
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CRST - Specific Carrier Restricted
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ICP - Intercept
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RCFA - Remote Call Forwarding appearance
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ROTL - Remote Office Test Line
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STN - Station Definition
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EQA Equal Access
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CARR - Carrier Data Items
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CC - Country Codes
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HUNT Hunting
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DNH - Directory Number Hunting
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EBS - Enhanced Business Services hunting
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KEY - Stop hunt or random make busy hunting
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LAN Local Area Network
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LAC - LAN Application Controller
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LCI - LAN CPU Interface
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LSHF - Message LAN Shelf
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NET Network
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D1PK - DS-1 interface pack (SCM-10S)
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1FAC - Interface packs
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LCM - Line Concentrating Module
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LCMC - Line Concentrating Controller Module
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NWPK - Network Packs
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RCT - Remote Concentrator Terminal
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REM - Remote Equipment Module
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RSLC - Remote Subscriber Line Module Controller
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RSLE - Remote Subscriber Line Equipment
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RSLM - Remote Subscriber Line Module
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SCM - Subscriber Carrier Module (DMS-1)
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SCS - SCM-10S shelf (SLC-96)
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SRI - Subscriber Remote Interface pack
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NTWK Network
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ACT - AC Testing definition
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D1PK - DS-1 interface pack (SCM-10S)
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DCM - Digital Carrier Module
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1FAC - Interface packs
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LCM - Line Concentrating Module
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LPK - Line Concentrating Equipment line packs
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NWPK - Network packs
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PACK - Peripheral Equipment packs
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PMS - Peripheral Maintenance System packs
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PSHF - Peripheral Equipment Shelf
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RCT - Remote Concentrator Terminal
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REM - Remote Equipment Module
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RSHF - Remote Shelf
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SBLN - Standby line
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SCM - Subscriber Carrier Module
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SCS - SCM-10S Shelf (SLC-96)
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SLC - SLC-96
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SLPK - SLC-96 Line Packs
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SRI - Subscriber Remote Interface (RLCM)
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ODQ Office Data Query
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ACDN - Access Directory Number
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CG - Carrier group
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CNTS - Counts
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DN - Directory Number
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DTRK - Digital Trunks (line and trunk)
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LINE - Lines (line and trunk)
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PIN - Personal Identification Number
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STOR - Memory Storage
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TG - Trunk Group
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TRK - Trunks (line and trunk)
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QTRN Query Translations
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ADDR - Address Translations
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EBSP - Enhanced Business Services prefix translations
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ESAP - Emergency Stand-Alone Prefix
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PRFX - Prefix translations
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SCRN - Screening translations
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TRVR - Translation verification
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ROUT Routes
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CONN - Nailed-up connections
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DEST - Destinations
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POS - Centralized Automatic Message Accounting positions
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ROUT - Routes
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TR - Toll regions
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SNET CCS7 Signaling Network
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SNLS - Signaling Link Set
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SNL - Signaling Link
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SNRS - Signaling Network Route Set
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TG Trunk Groups
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INC - Incoming trunk groups
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OUT - Outgoing trunk groups
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2WAY - Two-way trunk groups
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THGP Thousands Groups
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TRAC Call Tracing
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TRK Trunks
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DTRK - Digital Trunks
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TRK - Analog or digital recorded announcement trunks
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TRNS Translations
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ADDR - Address translations
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EBSP - EBS prefix translations
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ESAP - Emergency Stand-Alone prefix
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PRFX - Prefix translations
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SCRN - Screening translations
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V. SPEC SHEET
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Maximum # Subscriber Lines: 10,800
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(in stand-alone mode)
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Maximum # Trunks: 3,408
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- Incoming Trunk Groups: 127
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- Outgoing Trunk Groups: 127
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- Two-way Trunk Groups: 127
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- Maximum Routes: 512
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- Maximum Trunks per Group: 255
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Directory Numbers: 16,000
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Office Codes: 8
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Home Numbering Plan Area: 4
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Thousands Groups: 64
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Number of Network Groups: 1 or 2
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Total Network Capacity:
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- One Network Module: 5,400 POTS lines + 600 trunks
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- Two Network Module: 10,800 POTS lines + 1,200 trunks
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Traffic
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- Busy Hour Calls 38,000
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- Average Busy Season 29,000
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Busy Hour Attempts
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- CCS per line 5.18 centi call seconds
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- CCS per trunk 27.0 centi call seconds
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- Total CCS 133,000 centi call seconds
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Outpulsing DP, MF, or DTMF
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Inpulsing
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- Trunks DP, MF, or DTMF
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- Lines DP or DTMF
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Register Capacity
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- Outgoing DP=16 digits
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DTMF=16 digits
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MF=14 digits+KP+ST
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LEAS MF=20 digits+KP+ST
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[LEAS Route Access]
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- Incoming DP=14 digits
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DTMF=16 digits
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MF=14 digits
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VI. LIMITED GLOSSARY
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DP - Dial Pulse. A form of signaling that transmits pulse trains to indicate
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digits. Slow compared to DTMF and MF. Made obsolete by DTMF. Old
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step-by-step switches use this method, and there are still quite a few
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subscriber lines that use DP, even though DTMF is available.
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In-band Signaling - Transmitting control signals in the 300 - 3300 hz voice
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band, meaning that they're audible to subscribers.
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Out-of-band Signaling - Transmitting control signals above or below the 300 -
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3300 hz voice band. See SS7, CCS7.
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DTMF - Dual Tone Multi-Frequency. A form of in-band signaling that transmits
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two tones simultaneously to indicate a digit. One tone indicates the
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row and the other indicates a column. A fast, technically simple way of
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dialing that is in use almost all over the United States. White boxes
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generate DTMF tones, a.k.a. "Touch Tones" or Digitones. See DP, MF.
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MF - Multi-frequency. A form of in-band signaling similar to DTMF, except the
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signals are encoded differently (i.e., the row and column tones are
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different, because the keypad for MF tones isn't laid out in a rectangular
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matrix). These are the "operator tones." Blue boxes generate these
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tones. See DTMF, In-band signaling.
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CCS7 - Common Channel Signaling 7. Part of the Signaling System 7
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specification, CCS7 transmits control signals either above or below the
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voice band to control switch equipment, so control signals may be
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transmitted simultaneously with voice. See SS7.
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SS7 - Signaling System 7. An inter-switch signaling protocol developed by
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Bellcore, the RBOCs' research consortium. Relatively new, this protocol
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can be run only on digital switches. See CCS7, CLASS.
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CLASS - Custom Local Area Signaling Services. Several subscriber-line features
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that are just being introduced around the United States at the time of
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this article. See SS7, CCS7.
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Centrex - A scheme that turns a switch into an off-site PBX for business users.
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It can usually co-exist with existing lines.
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If anyone has any more questions, contact me at WWIVNet THE CAVALIER@3464.
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Thanks to Northern Telecom (the nicest sales staff in the world of switch
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manufacturers, with a killer product to boot!), Pink Flamingo, Taran King,
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Grim, and the crew who supported the NFX in "days of yore."
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