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Lucent Technologies DEFINITY Enterprise Communications Server Release 6 Instructions Manual
Lucent Technologies DEFINITY Enterprise Communications Server Release 6 Instructions Manual
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DEFINITY Enterprise Communications Server Release 6 Maintenance for R6r Volumes 1 & 2 555-230-126 Issue 2 January 1998 Maintenance Architecture Page 1-25 Protocols 1 Layers The Open System Interconnect (OSI) model for data communications contains seven layers, each with a specific function. Communications to and through the system concern themselves only with layers 1 and 2 of the model. Layer 1, or the physical layer, covers the physical interface between devices and the rules by which bits are passed. Among the physical layer protocols are RS-232, RS-449, X.21, DCP, DS1, and others. Layer 2, or the data-link layer, refers to code created and interpreted by the DCE. The originating equipment can send blocks of data with the necessary codes for synchronization, error control, or flow control. With these codes, the destination equipment checks the physical-link reliability, corrects any transmission errors, and maintains the link. When a transmission reaches the destination equipment, it strips any layer-2 information the originating equipment may have inserted. The destination equipment only passes to the destination DTE equipment the information sent by the originating DTE equipment. The originating DTE equipment can also add layer-2 code to be analyzed by the destination DTE equipment. The DCE equipment treats this layer as data and passes it along to the destination DTE equipment as it would any other binary bits. Layers 3 to 7 (and the DTE-created layer 2) are embedded in the transmission stream and are meaningful only at the destination DTE equipment. Therefore, they are shown in the figure as ‘‘user-defined,’’ with no state changes until the transmission stream reaches its destination.
DEFINITY Enterprise Communications Server Release 6 Maintenance for R6r Volumes 1 & 2 555-230-126 Issue 2 January 1998 Maintenance Architecture Page 1-26 Protocols 1 Figure 1-9. Data Transmission States DCE ORIGINATING DCE DESTINATION SYSTEM RS232C RS232CRAW BITSDCPDCP 1 DTE 2DMIASCIIASCII 3-7 USER DEFINED D I G I T A LP O R T D I G I T A LP O R T D I G I T A LP O R T D I G I T A LP O R T DATA MODULE DATA MODULE DATA MODULE DATA MODULE DTE DTE DATA MODULEDS1 PORT 1 D I G I T A LP O R T RAW BITS RS232CDS1 FORMATDCP DMIASCII 2 P O R T D S 1 DTE T R U N KP O R T A N A L O G ADUADUDTEE I AP O R TE I AP O R TDTE DMIASYNCH ASCIIASYNCH ASCII 2 3-7 USER DEFINED RS232CRS232CADU PROTADU PROT1 RAW BITS 3-7 USER DEFINED VOICE GRADE DATAASCIIASCII 2 ANALOGANALOG1PCMRS232CRS232C P O R T A N A L O GL I N E A N A L O GP O R T DTE DTEMODEM POOLING CABLE MODEM MODEM MODEM PCM 3-7USER DEFINED
DEFINITY Enterprise Communications Server Release 6 Maintenance for R6r Volumes 1 & 2 555-230-126 Issue 2 January 1998 Maintenance Architecture Page 1-27 Protocols 1 Usage The following is a list of the protocols when data is transmitted to and through the system. The list is organized by protocol layers. Refer to Figure 1-9 . Layer-1 Protocols Layer-1 protocols are used between the terminal or host DTE and the DCE, used between the DCE equipment and the system port, and used inside the system. The following layer-1 protocols are used between the DTE equipment and the DCE equipment. DCE equipment can be data modules, modems, or Data Service Units (DSUs). A DSU is a device that transmits digital data to a particular digital endpoint over the public network without processing the data through any intervening private network switches. nRS-232 — A common physical interface used to connect DTE to DCE. This protocol is typically used for communicating up to 19.2 kbps nRS-449 — Designed to overcome the RS-232 distance and speed restrictions and lack of modem control nV.35 — A physical interface used to connect DTE to a DCE. This protocol is typically used for transmissions at 56 or 64 kbps The following protocols are used at layer 1 to govern communication between the DCE equipment and the port. These protocols consist of codes inserted at the originating DCE and stripped at the port. The DS1 protocol can be inserted at the originating, outgoing trunk port and stripped at the destination port. nDigital Communications Protocol (DCP) — A standard for a 3-channel link. This protocol sends digitized voice and digital data in frames at 160 kbps. The channel structure consists of two information (I) channels and one signaling (S) channel. Each I-channel provides 64 kbps of voice and/or data communication and the S-channel provides 8 kbps of signaling communication between the system and DTE equipment. DCP is similar to ISDN-BRI nBasic Rate Interface (BRI) — An ISDN standard for a 3-channel link, consisting of two 64-kbps bearer (B) channels and one 16-kbps signaling (D) channel. For the implementation of this standard, see DEFINITY Communications System and System 75 and System 85 ISDN BRI Reference , 555-025-103 nPrimary Rate Interface (PRI) — An ISDN standard that sends digitized voice and digital data in T1 frames at 1.544-Mbps or, for countries outside the United States, in E1 frames at 2.048-Mbps. Layer 1 (physical), layer 2 (link), and layer 3 (network) ISDN PRI protocols are defined in AT&T System 75 and 85 — DS1/DMI/ISDN-PRI — Reference Manual, 555-025-101. At 1.544 Mbps, each frame consists of 24 64-kbps channels plus 8 kbps for framing. This represents 23 B-channels plus 1 D-channel.
DEFINITY Enterprise Communications Server Release 6 Maintenance for R6r Volumes 1 & 2 555-230-126 Issue 2 January 1998 Maintenance Architecture Page 1-28 Protocols 1 The maximum user rate is 64 kbps for voice and data. The maximum distances are based on T1 limitations. At 2.048 Mbps, each E1 frame consists of 32 64-kbps channels nAnalog — A modulated voice-frequency carrier signal nADU Proprietary — A signal generated by an ADU. The signal is for communication over limited distances and can be understood only by a destination ADU or destination system port with a built-in ADU nDigital Signal Level 1 (DS1) — A protocol defining the line coding, signaling, and framing used on a 24-channel line. Many types of trunk protocols (for example, PRI and 24th-channel signaling) use DS1 protocol at layer 1 nEuropean Conference of Postal and Telecommunications rate 1 (CEPT1) — A protocol defining the line coding, signaling, and framing used on a 32-channel line. Countries outside the United States use CEPT1 protocol Inside the system, data transmission appears in one of two forms: 1. Raw digital data, where the physical layer protocols, like DCP, are stripped at the incoming port and reinserted at the outgoing port. 2. Pulse Code Modulation (PCM)-encoded analog signals (analog transmission by a modem), the signal having been digitized by an analog-to-digital coder/decoder (CODEC) at the incoming port. Layer-2 Protocols Layer-2 protocols are given below: n8-bit character code — Between the DTE equipment and the DCE equipment. Depending on the type of equipment used, the code can be any proprietary code set. nDigital multiplexed interface proprietary — Family of protocols between the originating DCE and the destination DCE for digital transmission. See DEFINITY Communications System and System 75 and System 85 DS1/DMI/ISDN PRI Reference , 555-025-101; and Digital Multiplexed Interface [DMI] Technical Specification, 555-025-204 nVoice-grade data — Between the originating DCE and the destination DCE for analog transmission
DEFINITY Enterprise Communications Server Release 6 Maintenance for R6r Volumes 1 & 2 555-230-126 Issue 2 January 1998 Maintenance Architecture Page 1-29 Protocols 1 Protocol States Table 1-5 summarizes the protocols used at various points in the data transmission stream. See Figure 1-9 . NOTE: OSI means Open Systems Interconnect PCM means Pulse Code Modulated DMI means Digital Multiplexed Interface Table 1-5. Protocol States for Data Communication Transmiss- ion TypeIncoming DTE to DCEOSI LayerProtocols DTE to DCEDCE to System Port Inside System Analog Modem 1 RS-232, RS-449, or V.35analog PCM 2 8- or 10-bit code voice-grade data voice-grade data ADU 1 RS-232 ADU proprietary raw bits 2 asynchronous 8-bit codeasynchronous 8-bit codeDMI Digital Data Module1 RS-232, RS-449, or V.35DCP or BRI raw bits 2 8-bit code DMI DMI Digital Signal Level 1 (DS1)1 any DS1 PCM or raw bits 2 8-bit code DMI or voice- grade dataDMI or voice- grade data
DEFINITY Enterprise Communications Server Release 6 Maintenance for R6r Volumes 1 & 2 555-230-126 Issue 2 January 1998 Maintenance Architecture Page 1-30 Protocols 1 Both the physical-layer protocol and the Digital Multiplexed Interface (DMI) mode used in the connection are dependent upon the type of 8-bit code used at layer 2 between the DTE equipment and DCE equipment, as listed in Table 1-6 and Table 1-7 . Connectivity Rules Figure 1-9 implies the following connectivity rules: nOnly the DS1 port and the analog trunk port are trunking facilities (all other ports are line ports). For communication over these facilities, the destination DCE equipment can be a hemisphere away from the system, and the signal can traverse any number of intervening switching systems before reaching the destination equipment. nData originating at any type of digital device, whether DCP or BRI, can exit the system at any type of digital port — BRI, digital-line, PRI, DS1, and others; as long as the call destination is equipped with a data module using the same DMI mode used at the call origin. This is because once the data enters the system through a digital port, its representation is uniform (raw bits at layer 1, and DMI at level 2), regardless of where it originated. Table 1-6. Physical-Layer Protocol Versus Character Code Protocol Code RS-232 Asynchronous 8-bit ASCII, and synchronous RS-449 Asynchronous 8-bit ASCII, and synchronous V.35 Synchronous Table 1-7. Digital Multiplexed Interface (DMI) Mode Versus Character Code DMI Mode Code 0 Synchronous (64 kbps) 1 Synchronous (56 kbps) 2 Asynchronous 8-bit ASCII (up to 19.2 kbps), and synchronous 3 Asynchronous 8-bit ASCII, and private proprietary
DEFINITY Enterprise Communications Server Release 6 Maintenance for R6r Volumes 1 & 2 555-230-126 Issue 2 January 1998 Maintenance Architecture Page 1-31 Protocols 1 nAlthough data entering the system through an EIA port has not been processed through a data module, the port itself has a built-in data module. Inside the system, port data is identical to digital line data. Data entering the system at a DCP line port can exit at an EIA port. Conversely, data entering the system at an EIA port can exit at any DCP line port. The destination data module must be set for Mode-2 DMI communication. nVoice-grade data can be carried over a DS1 facility as long as the destination equipment is a modem compatible with the originating modem nIf a mismatch exists between the types of signals used by the endpoints in a connection (for example, the equipment at one end is an analog modem, and the equipment at the other end is a digital data module), a modem-pool member must be inserted in the circuit. When the endpoints are on different switches, it is recommended that the modem-pool member be put on the origination or destination system. A modem-pool member is always inserted automatically for calls to off-premises sites via analog or voice-grade trunking. For internal calls, however, the systems are capable of automatically inserting a modem-pool member. nData cannot be carried over analog facilities unless inside the system it is represented as a Pulse Code Modulation (PCM)-encoded analog signal. To do this for data originating at a digital terminal, the signal enters the system at a digital port and exits the system at a digital port. The signal then reenters the system through a modem-pool connection (data-module to modem to analog-port) and exits the system again at an analog port. nAlthough DS1 is commonly called a trunk speed, here it names the protocol used at layer 1 for digital trunks. Some trunks use different signaling methods but use DS1 protocol at layer 1 (for example, PRI and 24th-channel signaling trunks). Disconnect Supervision Disconnect supervision means the CO has the ability to release a trunk when the party at the CO disconnects, and the system is able to recognize the release signal. In general, a CO in the United States provides disconnect supervision for incoming calls but not for outgoing calls. Many other countries do not provide disconnect supervision on either incoming or outgoing calls. The system must provide the assurance that at least one party on the call can control the dropping of the call. This avoids locking up circuits on a call where no party is able to send a disconnect signal to the system. Internal operations must check to be sure one party can provide disconnect supervision. An incoming trunk that does not provide disconnect supervision is not allowed to terminate to an outgoing trunk that does not provide disconnect supervision. In a DCS environment, an incoming trunk without disconnect supervision can terminate to an outgoing DCS trunk connecting two nodes. The incoming trunk is restricted from being transferred to a party without disconnect supervision on the terminating node.
DEFINITY Enterprise Communications Server Release 6 Maintenance for R6r Volumes 1 & 2 555-230-126 Issue 2 January 1998 Maintenance Architecture Page 1-32 Protocols 1 This is because, through messaging, the terminating node knows the originating node cannot provide disconnect supervision. This messaging is not possible with non-DCS tie trunks, and the direct call is denied. Some two-wire loop start trunks outside the United States provide busy tone disconnect in place of line signals. For these trunks, an adjunct can be attached to the trunk to listen for busy or other disconnect tone. When a tone is detected, the adjunct sends line signals for disconnect to the system. Administration is provided for each trunk group to indicate whether it provides disconnect supervision for incoming calls and for outgoing calls. Transfer on Ringing A station or attendant may conference in a ringing station or transfer a party to a ringing station. When a station conferences in a ringing station and then drops the call, the ringing station is treated like a party without disconnect supervision. However, when a station transfers a party to a ringing station, the ringing station party is treated like a party with disconnect supervision. Two timers (Attendant Return Call Timer and Wait Answer Supervision Timer) are provided to ensure the call is not locked to a ringing station. Conference, Transfer, and Call-Forwarding Denial If a station or attendant attempts to connect parties without disconnect supervision together, the following is possible: nDigital Station or Local Attendant Transfer: if a digital station attempts to transfer the two parties together, the call appearance lamp flutters, indicating a denial. If transferring to a DCS trunk, the denial may drop the call since the transfer is allowed and the other system is queried for disconnect supervision. nAnalog Station Transfer: if an analog station attempts to transfer two parties together by going on-hook, the analog station is no longer on the call and the transfer cannot be denied. nCentralized Attendant Service (CAS) Attendant Transfer: if a CAS attempts to transfer two parties together by pressing the release key, the release link trunk is released and the branch attempts a transfer by going on-hook nStation Conference/Dropout: if a station conferences all parties, the conference is allowed since the station has disconnect supervision. When the station is dropped from the call, the call is dropped since the other parties do not have disconnect supervision. nStation Call Forwarding: if a station is call forwarded off-premise to a trunk without disconnect supervision, the calling party without disconnect supervision is routed to the attendant Table 1-8 lists the various protocols, with applications and maximum limitations.
DEFINITY Enterprise Communications Server Release 6 Maintenance for R6r Volumes 1 & 2 555-230-126 Issue 2 January 1998 Maintenance Architecture Page 1-33 Protocols 1 Table 1-8. Protocols Used in DEFINITY Protocol ApplicationsMaximum Data Rate Maximum Distance DCP Digital switch to data endpoints64 kbps 5000 feet (1524 m) for data 3000 feet (915 m) for voice RS-232 System to administration terminal. Data module to host computer Data module to printer Data module for downloading and high-speed data transfer EIA interface (Data line to ADU)19.2 kbps 64 kbps 64 kbps 19.2 kbps 9.6 kbps 4.8 kbps 2.4 kbps 1.2 kbps 0.3 kbps50 feet (15.2 m) 17 feet (5.9 m) 17 feet (5.9 m) 2000 feet (610 m) 5000 feet (1524 m) 7000 feet (2130 m) 12,000 feet (3654 m) 20,000 feet (6100 m) 40,000 feet (12200 m) RS-449 Processor Interface to Processor Interface19.2 kbps 9.6 kbps 4.8 kbps 2.4 kbps200 feet (61 m) 400 feet (122 m) 800 feet (244 m) 1600 feet (488 m) SSI 715 BCS-2 to Processor Interface 500 series printers to Processor Interface56 kbps 5000 feet (1524 m) BISYNC Processor Interface line controller to host computer for terminal emulation (9.6 kbps)2.4 kbps 4.8 kbps 9.6 kbps BX.25 Communication interface to MSA, DCS, ISDN, or AUDIX9.6 kbps SDCPI Data module to Processor Interface64 kbps 17 feet (5.9 m) RS-366 Host computer to ACU Data module to ACU 64 kbps50 feet (15.2 m) 17 feet (5.9 m) V.35 Data module to data endpoints56 kbps 50 feet (15.2 m) Continued on next page
DEFINITY Enterprise Communications Server Release 6 Maintenance for R6r Volumes 1 & 2 555-230-126 Issue 2 January 1998 Maintenance Architecture Page 1-34 Protocols 1 NOTE: ADU means Asynchronous Data Unit BCS means Business Communications System MSA means Message Servicing Adjunct ACU means Automatic Call Unit Transmission Characteristics The system transmission characteristics comply with the American National Standards Institute/Electronic Industries Association (ANSI/EIA) standard RS-464A (SP-1378A). The following tables list some general switch transmission characteristics. Category AData modules to terminals or cluster controller Data module in ASCII emulation mode64 kbps 9.6 kbps500 feet (152 m) ISDN-BRI Communication interface to ISDN-BRI S/T ISDN-BRI U64 kbps 160 kbps655 feet (199.3 m) to network interface or repeater 1310 feet (399.3 m) system to system 18,000 feet (5486.4 m) from system to network interface, and then ~2000 feet to phone ISDN-PRI Communication interface to ISDN-PRI64 kbps 655 feet (199.3 m) to network interface or repeater 1310 feet (399.3 m) system to system Table 1-8. Protocols Used in DEFINITY — Continued Protocol ApplicationsMaximum Data Rate Maximum Distance Continued on next page