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This appendix defines selected ATM terminology applicable to ATM Access Management.
ACLS - ATM Cell Loss Status; ACLS is accessible via the Circuit Emulation Service (CES) MIB defined by the ATM forum and/or the VT100 ATM Statistics screen.
Adaptive Timing - A non-required network-wide synchronization technique used to regenerate the input service clock; commonly used in structured Circuit Emulation Service (CES) mode.
AMI - Alternate mark inversion; a T1 (1.544 Mbps) carrier line coding format whereby successive ones (marks) are alternately inverted.
B8ZS - Binary 8 Zero Substitution; a T1 (1.544 Mbps) carrier line coding format used to accommodate "ones density" for clear channel transmission.
CAS - Channel Associated Signalling; the AccessBuilder 9600 supports CAS and will pass non-CAS signalling through the network on TS16 (Channel DS0 16). Signalling information is always disabled in E1 single-frame or unframed mode. Signalling information is always enabled in structured voice multi-frame mode.
CA - data Communications equipment Available; a control signal sent by the DCE (Data Circuit terminating Equipment), independently from TA (data Terminal equipment Available), when the DCE is prepared to both send and receive data to and from the DTE (Data Terminal Equipment) device.
CBR DSX - A module providing four or eight DSX D1 ports for transit over an ATM network.
CBR E1 - A module providing four or eight E1 ports for transit over an ATM network.
CDV Tolerance - Cell delay variation tolerance (CDVT). The CDVT value specifies the amount of cell delay uncertainty that may be experienced by any particular cell.
Cell Mapping - How the carrier will provision the DS3 UNI service from the carrier ATM switch. Clear (G.804) cell mapping is currently the option preferred by both domestic and international service providers and within private ATM networks, as it gives more payload bandwidth than PLCP (Physical Layer Convergence Protocol).
CLIP - Cell Loss Integration Period. If cells are lost within this period, the ATM Cell Loss Status (ACLS) is set to loss (2).
CRC4 - Cyclic Redundancy Check; CRC4 is a framing option that checks for errors in data. CRC4 is always disabled in E1 single-frame or unframed modes. CRC4 is always enabled in multi-frame mode with signalling disabled.
CTS - Clear to Send; a control signal used in the exchange of data between a DTE (Data Terminal Equipment) and a DCE (Data Circuit terminating Equipment) device.
CTX - The CTX module; a cell multiplexer between the port modules and the trunk UNI module.
DCD - Data Carrier Detect; a control signal to notify that a carrier signal is available, and that the terminal can send data.
DCE - Data Circuit terminating Equipment; equipment that is either part of the network, an access point to the network, a network node, or the point at which a network circuit terminates.
DFA VCI - The virtual channel indicator (VCI) number corresponding to the DFA field.
DFA VPI - The virtual path indicator (VPI) number corresponding to the DFA field.
DLCI - The frame relay Data Link Connection Identifier. DLCI is used to identify a frame relay local connection.
DS3 - Digital signal level 3; the term used to describe the 44 Mbps digital signal carried over a T3 digital channel.
DSR - Data Set Ready; a control signal from the DTE (Data Terminal equipment) device that it is ready to send data from the terminal.
DTE - Data Terminal Equipment; generally end-user devices, such as terminals and computers - which connect to DCE (Data Circuit terminating Equipment) - that either generate or receive data carried by the network.
DTR - Data Terminal Ready; a control signal sent from the DTE (Data Terminal Equipment) device (router, etc.) to the DCE (Data Circuit terminating Equipment) device (AccessBuilder 9600) that indicates the DTE device is ready to communicate. DTR is also used for flow control purposes.
DXI - Data eXchange Interface.
FEAC Loopback - Loopback activate and deactivate FEAC codes sent from the central office. Service providers use FEAC codes to obtain downstream or upstream conditions of a DS3 network. When FEAC loopback is enabled, the system responds to a loopback activate command by enabling the DS3 line loopback. The system removes the loopback automatically after 15 minutes or when it receives the deactivate command.
FEP - Front-End Processor.
FR-SSCS DLCI - Frame Relay SSCS DLCI; a connection encapsulated into ATM PDU with AAL5.
FRAD - Frame Relay Assembler and Disassembler or Frame Relay Access Devices.
HDB3 - High Density Bipolar Three; an E1 (2.048 Mbps) carrier line coding format that does not allow more than three consecutive zeros.
HSIM - High-speed Serial Interface Module; a module designed to interconnect frame-based devices/networks and cell-based ATM devices/networks. HSIM provides four HDLC serial interfaces and an ATM SAR. It is able to perform cell-to-frame as well as frame-to cell conversion.
HSSI - High-Speed Serial Interface; a serial communications connection that operates at up to 1.544 Mbps (T1 speeds).
LBO - Line build out. The signal generation/regeneration of the distance between the AccessBuilder 9600 and the next crossconnect or FOTs (Fiber Optic Terminal system).
Mode 1 Mapping - An operational method for indicating data congestion to either the ATM or Frame Relay network. This mode does not translate between Frame Relay (NLPID) and LLC-SNAP encapsulation, rather it sends it straight through the ATM network, possibly onto a Frame Relay network or device.
Mode 2 Mapping - An operational method for indicating data congestion to either the ATM or Frame Relay network. This mode allows for translation between Frame Relay (NLPID) and LLC-SNAP encapsulation. It is used when connecting a Frame Relay device or network to a non-Frame-Relay device or network. For example, if the AccessBuilder 9600 is connecting a router/FRAD over an ATM network (public or private) and at the other site a router with an ATM OC3/STM-1 UNI is connected to the WAN network, typically the router OC3/STM-1 UNI does not support NLPID and requires mode 2 mapping so that the packet can be encapsulated to LLC-SNAP.
Payload Size - The actual number of payload octets used per ATM cell size configured for the specified T1/E1 ATM VC connection.
Payload Scrambling - A technique used to avoid certain transmission equipment behaviors (for example, erroneous alarm conditions) that are caused by sensitivity to certain bit patterns in the AT payload.
PLCP - Physical Layer Convergence Protocol.
QSIM - Quad Serial Interface Module; a module designed to interconnect frame-based devices/networks and cell-based ATM devices/networks. QSIM provides four HDLC serial interfaces and an ATM SAR. It is able to perform cell-to-frame as well as frame-to cell conversion.
Recv Ckt - The receive path trace. The path trace is a byte used to repetitively transmit a 64-byte fixed length string so that a receiving terminal in a path can verify its continued connection to the intended transmitter.
RTS - Request To Send; a control signal sent from the terminal device to the DCE (Data Circuit terminating Equipment) device (AccessBuilder 9600) to begin the information flow.
RxVCI - The receive virtual channel indicator (VCI) number.
RxVPI - The receive virtual path indicator (VPI) number.
SDH - Synchronous Digital Hierarchy; the European equivalent of SONET.
Shaper - The control rate at which ATM cells are transmitted on a specific connection.
SONET - Synchronous Optical Network; a high-speed synchronous system technology used on fiber-optic cable networks.
SRTS Timing - Synchronous Residual Time Stamp; a means to measure the service clock frequency against a network-wide synchronization signal. SRTS is only used in the unstructured Circuit Emulation Service (CES) mode for the CBR traffic.
Structured Data Mode - A port mode; the type of service configured to the specified T1/E1 port interface. Structured service provides N x 64 kbit/second capability, where N ranges between 1 and the maximum number of available DS0 channels. Structured data service passes traffic with signalling information disabled.
Structured Voice Mode - A port mode; the type of service configured to the specified T1/E1 port interface. Structured service provides N x 64 kbit/second capability, where N ranges between 1 and the maximum number of available DS0 channels. Structured voice service passes traffic with signalling information enabled.
T1 - A digital carrier facility for transmitting a digital stream at 1.544 Mbps.
TA - data Terminal equipment Available; a control signal sent by the DTE (Data Terminal Equipment) device, independently from CA (data Communications equipment Available), when the DTE is prepared to both send and receive data to and from the DCE (Data Circuit terminating Equipment) device.
TxVCI - The transmit virtual channel indicator (VCI) number.
TxVPI - The transmit virtual path indicator (VPI) number.
Unstructured Mode - A port mode; the type of service configured to the specified T1/E1 port interface. Unstructured service allows the application to utilize the entire available bandwidth at a bit rate of 1.544 Mbps for T1 interfaces or 2.048 Mbps for E1 interfaces. T1/E1 framing is optional in this service mode.
VCI - Virtual Channel Indicator.
VPI - Virtual Path Indicator.
Xmt Ckt - The transmit path trace. The path trace is a byte used to repetitively transmit a 64-byte fixed length string so that a receiving terminal in a path can verify its continued connection to the intended transmitter.