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This page contains a list of acronyms and abbreviations associated with Ribbon IP Optical products.

1

  • 1:n (Protection Architecture): 1:n protection architecture (n ³ 1) has n normal traffic signals, n working SNCs/trails, and one protection SNC/trail. It may have one extra traffic signal.
  • 1+1 (Protection Architecture): Method of protecting traffic in which a protection channel exists for each working channel. In optical systems, protection channel fibers can be routed over a path separate from working fibers. The signal is bridged to both transmitters.
  • 10BaseT: Ethernet LAN transmitting data over twisted pair wiring at 10 Mbps baseband
  • 100BaseT: 100 Mbps baseband data LAN transmission running over twisted pair copper cable (also called Fast Ethernet). Three basic implementations of Fast Ethernet (100BaseFX, 100BaseT, and 100BaseT4) are identical except for the interface circuitry.
  • 1000BaseCX: Standard for Gigabit Ethernet (GbE) connectivity. 1000 Mbps baseband Ethernet over shielded 150 W twin axial cable up to 25 meters in length.
  • 1000BaseLX: Standard for Gigabit Ethernet (GbE) connectivity. 1000 Mbps baseband Ethernet over long-wave lasers on single-mode or multimode optical fibers.
  • 1000BaseSX: Standard for Gigabit Ethernet (GbE) connectivity. 1000 Mbps baseband Ethernet over short-wave lasers on single-mode or multimode optical fibers.
  • 1000BaseT: Standard for Gigabit Ethernet (GbE) connectivity. 1000 Mbps baseband Ethernet over four CAT5 shielded twisted pair cables at ranges up to 100 meters. Also known as Gigabit Ethernet (GbE, GigE).
  • 1000BaseX: Standard for 1000 Mbps (Gigabit) Ethernet connectivity
  • 1R: Regeneration (amplification)
  • 1U: One unit

2

  • 2G: 2nd-generation of broadband cellular network technology
  • 2R: Regenerating and reshaping

3

  • 3G: 3rd generation of broadband cellular network technology
  • 3GPP: 3rd Generation Partnership Project
  • 3P: Triple play services - voice, video, data
  • 3R: Regenerating, retiming, reshaping

4

  • 4G: 4th generation of broadband cellular network technology

5

  • 5G: 5th generation of broadband cellular network technology

8

  • 802.3 network: 10 Mbps CSMA/CD bus-based network, commonly called Ethernet, complying with the IEEE 802.3 standard

A

  • A&A: Add and Add
  • A&D: Add and Drop
  • AAA: Triple A - Authentication, Authorization, and Accounting
  • AAL: ATM Adaptation Layer or Asynchronous Adaptation Layer
  • AAL-1: AAL-1 payload type, for example, CES
  • AAL-2: AAL-2 payload type, for example, for compressed voice
  • AAL-5: AAL-5 payload type, for example, for signaling
  • ABO: Alarm-Bearing Object

  • ABR: Area Border Router or Available Bit Rate (ATM QoS class)
  • AC: Attachment Circuit
  • ACA: Auto Card Assignment
  • ACK: Alarm acknowledged
  • ACL: Access Control List
  • ACM: Address Complete Message or Alarm Connector Module

  • ACO: Alarm Cut-Off

  • ACP: ASON Control Plane card

  • AD: Active Directory, Administrative Domain
  • ADM: Add/Drop Multiplexer. System adding and dropping lower level signals to and from a higher level carrier signal.
  • ADPSK: Adaptive Phase Shift Keying
  • ADSL: Asymmetric Digital Subscriber Line
  • AES: Advanced Encryption Standard

  • AFC: Automatic Frequency Control
  • AFI: Address Family Identifier or Authority and Format Identifier
  • AFR: Absolute Frequency Reference
  • AGW: Access Gateway
  • AICS: Application Identification Channel Signal
  • AIN: Advanced Intelligent Network
  • AINS: Automatic In-Service
  • AIS: Alarm Indication Signal
  • AIS-L: Alarm Indication Signal - Line
  • AIS-P: Alarm Indication Signal - Path
  • AIS-V: Alarm Indication Signal - Virtual (tributary)
  • ALpa: Actual Loss from previous amp
  • ALS: Automatic Laser Shutdown
  • AMU: Alarms & Maintenance Unit
  • AMXE: Aggregate interface module with highest rate of 10GE (Neptune)
  • ANC:  Access Network Controller
  • ANCP: Access Node Control Protocol
  • ANOC: Actual number of channels or Alternate Network Operations Control
  • ANSI: American National Standard Institute
  • AoC: ADM on a Card or Active Optical Cable (used as the prefix of various Apollo cards (see AoC10_L2, AoC10/AoC10B))
  • AOS: Automatic Optical Switch
  • AP: Access Point
  • APC: Automatic Power Control
  • APD: Avalanche Photodiode
  • API: Application Programmer Interface
  • APR: Automatic Power Reduction or Address Resolution Protocol
  • APS: Automatic Protection Switching
  • ARP : Access Resolution Protocol
  • ARPU: Average Revenue Per User

  • ARS: Address Reachability Service or Automatic Route Selection
  • AS: Autonomous System
  • ASA: Automatic Slot Assignment
  • ASBR: Autonomous System Border Router or Autonomous System Boundary Router
  • ASCII: American Standard Code for Information Interchange
  • ASIC: Application Specific Integrated Circuit

  • ASM: Any Source Multicast model.
  • ASON: Automatically Switched Optical Network
  • ASP: Application Service Provider

  • ASTN: Automatic Switched Transport Network
  • ATE: Automatic Test Equipment
  • ATM: Asynchronous Transfer Mode. Cell relay data transmission technique transferring data from multiple sources in small fixed-size packets (cells).

  • ATMF: ATM Forum
  • Attenuation: Decrease (loss) in the power of a signal during transmission between points, normally measured in decibels (dB). When used to express the total loss of an optical system, indicates the total attenuation at a specific wavelength.
  • Attenuator: In electrical systems, a normally passive network for reducing the amplitude of a signal without appreciably distorting the waveform. In optical systems, a passive device for reducing the amplitude of a signal without appreciably distorting the waveform.
  • ATU: ADSL Transceiver Unit
  • AU: Administrative Unit (in the SDH structure)
  • AU-3: Administrative Unit 3
  • AU-AIS/AIS-P: AU Alarm Indication Signal/Alarm Indication Signal - Path
  • AUG: Administrative Unit Group (in the SDH structure)
  • AUI: Access Unit Interface
  • AU-LOP/LOP-P: AU Loss of Pointer/Loss of Pointer - Path
  • Auto provisioning: Assignment of values to parameters within an NE not specifically entered by an external user
  • AUX: Auxiliary
  • AWG: Array Waveguide Grating. Device used for wavelength demultiplexing in WDM applications.

B

  • Backbone: High capacity network linking other lower capacity networks
  • Backhauling: Traffic management technique of sending network data on an out-of-the-way route to the final destination in order to get there soonest. Used to reduce the expense of multiplexing/demultiplexing.
  • Bandwidth: In digital devices, loosely used to indicate data rate (amount of data transmitted in a fixed amount of time), usually expressed in bps or Bps. In analog devices, some performance characteristics of a range of frequencies that fall within specific limits (for example, 3 dB bandwidth), usually expressed in cycles per second or Hertz (Hz).
  • Baseband: Band of frequencies occupied by a signal before it modulates a carrier/subcarrier to form a transmitted line, optical or radio signal
  • BB: Broadband or Baseband
  • BBA: Broadband Access
  • BB-DXC: Broadband Digital Cross Connect
  • BBE: Background Block Error
  • BC: Boundary Clock
  • BDI: Backward Defect Indication
  • BD-VSI: Bridge Domain Virtual Switch Interface
  • BE: Best Effort
  • BEI: Backward Error Indication
  • BER: Bit Error Ratio. The number of bit errors detected in a unit of time, usually 1 second.
  • BFD: Bidirectional Forwarding (or Fault) Detection
  • BGP: Border Gateway Protocol
  • BIAE: Backward Incoming Alignment Error
  • BIP: Bit Interleaved Parity
  • BIT: Built-In Test
  • Bit interleaving: Method used in data transmission systems to mitigate the effects of noise bursts. Based on reordering bits in a sequence before transmission in accordance with prescribed rules, which ensures that, after interleaving, adjacent bits in any block of the original sequence are separated by a certain average distance. Deinterleaving at the receiver end restores the original bit sequence.
  • BITE: Built-In Test Equipment
  • BLER: Block Error Rate
  • BLSR: Bidirectional Line Switched Ring. Scheme in SONET rings in which traffic is sent on both rings in opposite directions. In the event of a fault, all traffic switches over to the other side of the ring.
  • BMP: Bit-Synchronous Mapping Procedure
  • Booster: Optical amplifier at the transmitter site
  • BPDU: Bridge Protocol Data Unit
  • bps: Bits per second
  • Bps: Bytes per second
  • BPSR: Bidirectional Path Switched Ring
  • Broadband: High speed transmission; term commonly used for communication lines/services at rates of 1.544 Mbps and more
  • Broadcast: Simultaneous transmission of data from one terminal via a network to all or a set of destinations
  • BS: Base Slot
  • BSC: Base Station Controller
  • BSHR: Bidirectional Self-Healing Ring
  • BSS: Base Station System or Broadband Switching System
  • BTS: Base Transceiver Station or Base Station Transceiver Subsystem
  • BW: Bandwidth

C

  • C band: Wavelength ranging from 1530 nm to 1562 nm, used in CWDM and DWDM applications

  • C4I: Command, control, communication, computer, and intelligence

  • CA:  Certificate Authority
  • CAC: Call Admission Control or Connection Admission Control (set of actions taken by the network during the call setup or renegotiation phase)
  • Capacity: Amount of information a telecommunications facility can carry or process on transmission lines, usually expressed in bps
  • CAPEX: Capital Expenditure
  • Carrier: Public or private company providing communications services, or transmitted electromagnetic pulse/wave at a steady base frequency on which information can be imposed
  • CAS: Channel Associated Signaling

  • CATV: Cable TV
  • CBR: Constant Bit Rate (ATM QoS class)
  • CBS: Committed Burst Size
  • CBU: Call-Back Unit
  • CBUS: Control Bus. The internal communication bus within Neptune.
  • CBWF: Call Back When Free (also known as Ring Back When Free)
  • CC: Cross Connect or Continuity Check (process using ATM cells to check if ATM link is active and operating normally)
  • CCI: Common Client Interface
  • CCM: Communication Channel Management, Current Call Meter, or Continuity Check Message
  • CCN: Common Communication Network or Content-Centric Networking
  • CCP: Central Connection Panel or Communication Control Panel
  • CDE: Common Desktop Environment
  • CDF: Client Data Frame
  • CDMA: Code Division Multiple Access (several protocols used in 2G and 3G wireless communications)

  • CDR: Call Data Report or Clock & Data Recovery
  • CDVID: Customer Domain VLAN ID
  • CE: Customer Edge or Corrected Errors
  • CECC: CENELEC Electronic Components Committee
  • CEM: Common Element Manager, Common Equipment Module, Customer Experience Management, or Common External Module
  • CEP: Circuit Emulation over Packet
  • CES: Circuit Emulation Service, used in ATM (see Multiservice (CES) Cards)

  • CESoPSN: Circuit Emulation Service over Packed Switched Network
  • CESR: Carrier Ethernet Switch/Router
  • CET: Carrier Ethernet Transport
  • CF: Call Forwarding or Compact Flash
  • CFG: Configuration
  • CFM: Connectivity Fault Management
  • CFP: C Form-Factor Pluggable transceiver type
  • Channel: Communications path. By using multiplexing, several channels can be transmitted over a single medium like copper or fiber. In wavelength division multiplexing (WDM) technology, a channel is assigned to a specific wavelength or lambda.
  • Channel capacity: Maximum number of channels that can be carried simultaneously in a cable system
  • Channel spacing: Separation between wavelengths by adjacent channels in WDM systems
  • Chirp: Signal of rapid change (as opposed to long-term drift) of wavelength of an electromagnetic wave during the duration of a pulse. Occurs in laser diodes during pulse mode operation. Found on STM-16 and up, and limits transmission distance on fibers.
  • Chromatic dispersion: Distortion of the optical signal shape caused by the variation of group delay. Function of light wavelength as the signal travels down the optical fiber.
  • CIDR: Classless Interdomain Routing
  • CIR: Committed Information Rate
  • Circuit: Communications path or network in transmission systems; usually a pair of channels providing bidirectional communication

  • CIT: Craft Interface Terminal

  • CK: Clock
  • CLE: Customer located equipment
  • Cleave: Controlled breaking of optic fiber
  • CLEC: Competitive Local Exchange Carrier. Company building and operating communications networks in metropolitan areas as an alternative to the local telephone company.

  • CLI: Command Line Interface
  • Clk: Clock
  • CLT: Central Loose Tube (see CLT_1510/1590)
  • CLU: Clock Unit
  • CMBR: Combiner Card
  • CMF: Client Management Frame
  • CMIP: Common Management Information Protocol. Network management protocol (MIB) built on the OSI communications model and used by an application to exchange information and commands in management of remote communications resources. CMIS is related to CMIP.
  • CMIS: Common Management Information Services. Services for controlling, accessing information, and receiving status reports from network objects/devices.
  • CMISE: Common Management Information Service Element. Application (7th) layer.
  • CMN: Customer Managed Network
  • CMOS: Complementary Metal Oxide Semiconductor
  • CMR - Combiner, used as the prefix of various OPT96xx service cards
  • CMS: Central Monitoring Station
  • CNM: Customer Network Manager
  • CNR: Carrier to Noise Ratio

  • CO: Cable Operator or Central Office (nerve center of a communications system; common carrier switching office in which user lines terminate)
  • COADM: Colorless OADM
  • CoC: Carrier of Carriers
  • COM: Communications Card
  • Concatenate/Concatenation: Linking together in a series or chain. Procedure whereby several virtual containers are associated together, resulting in their combined capacity being used as a single container across which bit sequence integrity is maintained (set of bits treated as a single entity).
  • Concentration: Fundamental concept in telephony applying to a switched network that has more inputs than outputs. Technique increases utilization of a composite multiplexer link. A statistical multiplexer or concentrator focuses channel inputs on to the composite link by removing those portions of the transmission carrying no data.
  • Consolidation: Allocation of server trails to client connections ensuring that each server trail is full before the next is allocated. For example, a number of partially filled VC‑4 paths may be consolidated into a single full VC‑4.
  • Container-n: Information structure forming the network synchronous information payload for a virtual container (n=1 to 4)
  • CO-PS: Common Open Policy Service
  • CORBA: Common Object Request Broker Architecture
  • CoS: Class Of Service
  • COTS: Commercial Off-The-Shelf
  • Coupler: Device that splits optical signals into multiple paths, or combines multiple signals into one path

  • CP: Connection Point

  • CPE: Customer Premise Equipment. Terminating equipment (terminals, phones, routers, modems) usually supplied by the phone company, installed at customer sites and connected to the phone company network.
  • CPI: Common Power Input
  • CPS: Calls Per Second or Centralized Packet Switch
  • CPTS: Centralized Packet TDM Switch
  • CPU: Central Processing Unit
  • CRC: Cyclic Redundancy Check
  • Cross connect: A connection scheme between cabling runs, subsystems, and other equipment, using patch cords or jumpers to connect hardware at each end. An intermediary system connecting, for example, blocks of incoming wiring from telecom companies to blocks of local office wiring. Simplifies changes, updates, and other operations done at the level of the cross-connect wires.
  • CSF: Client Signal Fail. Propagates indication of Ethernet interface failure at one end of a connection to the other.
  • CSFP: Compact Small Form-Factor
  • CSMA/CD: Carrier Sense Multiple Access with Collision Detection
  • CSPF: Constrained Shortest Path First
  • CSU: Channel Service Unit
  • CSV: Comma Separated Value
  • CT: Client Trail or Craft Terminal
  • CTCA: Current Threshold Crossing Alert
  • CTM: Cordless Terminal Mobility or Central Timing Module
  • CTP: Connection Termination Point
  • CU: Consolidation Unit
  • CUA: Central User Administration
  • CUOD: Consolidation Unit for Optical Distribution
  • CV: Code Violation
  • CVFE: Code Violation Far End
  • CVNE: Code Violation Near End
  • CVP: Client Virtual Port
  • CW: Continuous Wave
  • CWDM: Coarse Wavelength Division Multiplexing. Form of optical wavelength division multiplexing (see WDM) with wider spacing between channels, leading to considerable savings in laser transponder costs, power requirements, and footprints. See CWDM components.

D

  • Dark fiber: Inactive optical fiber. During initial laying of cables, some fibers are typically left dark or in reserve for future use.
  • DB: Database or Daughterboard
  • DBA: Dynamic bandwidth allocation
  • dBm: Logarithmic unit of power indicating power in dB relative to 1 mW (for example, +3 dBm = 0.5 mW)
  • DBMS: Database Management System
  • DBR: Distributed Bragg Reflector
  • DC: Direct Current
  • DCC: Digital communications channel, Digital control channel, or Data communication channel (data channels in SDH/SONET overhead used for internode communications and OAM&P communications between intelligent controllers and individual network nodes).
  • DCCm: DCC of multiplex channel (overhead bytes D4-D12)
  • DCCr: DCC of regenerator channel (overhead bytes D1-D3)
  • DCF: Distributed Coordination Function (see DCF cards) or Dispersion compensating fiber (fiber with dispersion characteristic opposite to that of the fiber used in the transmission system, so nullifying its dispersion).
  • DCM: Dispersion Compensation Module
  • DCN: Data Communications Network
  • DCR: Data Conversion Receiver or Dynamically controlled routing
  • DCS: Digital Cross-Connect System
  • DDF: Digital Distribution Frame
  • DDN: Digital Data Network
  • DDP: Document Delivery Package
  • DDRAM: External Double Data Rate Memory
  • Demultiplexing: Process applied to a multiplex signal for recovering signals combined within it and restoring the distinct individual channels of the signals
  • DeMux: Demultiplex, demultiplexer
  • DFF: Dispersion Flattened Fiber
  • DH: Data Hybrid, used as the prefix of various Neptune data cards
  • DHCE: 100GE Data Hybrid IO card (Neptune)
  • DHCP: Dynamic Host Configuration Protocol or Dynamic Host Control Protocol
  • DHFE_12: Data hybrid card that supports up to 12 x FE ports
  • DHGE: Data Hybrid GE
  • DHTM: Dual Homing Terminal Multiplexer
  • DHXE: 10GE Data Hybrid IO card (Neptune)
  • Diffraction: Modification undergone by light passing by the edges of opaque bodies, or through narrow slits, or reflected from ruled surfaces
  • Diffraction grating: Polished surface with finely spaced corrugated lines or surface grooves used to separate wavelengths
  • DIN: German institute for standardization
  • DIO: Data Input/Output card (GbE)
  • DIOB: Data I/O (B version)
  • DLC: Digital Loop Carrier or Data link control (or connection)
  • DM: Delay Measurement or Data Module (used as the prefix of various Neptune data cards)
  • DMCES: Data Module Circuit Emulation
  • DMFE: Data Module Fast Ethernet
  • DMGE: Data Module GE (Neptune)
  • DMI: Desktop Management Interface
  • DMM: Digital Multimeter
  • DN: Distinguished Name
  • DNI: Dual Node Interworking (or Interconnection) or Dual Node Interface
  • DNS: Domain Naming System
  • DoS: Denial of Service
  • DPBO: Downstream Power Backoff
  • DP-DQPSK: Polarization Differential Quadrature Phase Shift Keying
  • DP-QPSK: Dual Polarization- Quadrature Phase Shift Keying
  • DPRing: Dedicated Protection Ring
  • DQ: Data Quality
  • DRI: Dual Ring Interconnection or Dual Ring Interface
  • DRP: Disaster Recovery Plan
  • DS: Digital Signal (bit stream)
  • DS-0: Digital Signal level 0. North American digital telephony signal format for transmission at 64 kbps.
  • DS-1: Digital Signal level 1 (= T1). North American primary digital telephony signal format for transmission at 1.544 Mbps; carries 24 DS-0 signals.
  • DS-3: Digital Signal level 3. North American digital hierarchy signal format for transmission at 44.736 Mbps; carries 28 DS‑1 signals.
  • DSCP: Differentiated Services (Diffserv) Code Point
  • DSF: Dispersion shifted fiber
  • DSL: Digital Subscriber Line
  • DSLAM: Digital Subscriber Line Access Multiplexer
  • DS-n: Digital signal level n. Signal format in the North American digital multiplexing hierarchy. Trunks operating at a rate of DS‑n are called Tn lines (for example, a T1 line carries a DS‑1 signal).
  • DSP: Digital Signal Processor
  • DSR: Digital Signal Rate
  • DSU: Data Service Unit
  • DTC: Data Transfer Controller
  • DTD: Document Type Definition
  • DTE: Data Terminal Equipment
  • DTMF: Dual Tone Multifrequency
  • DTT: Digital Terrestrial Television
  • Duplex transmission: Transmission in both directions, either in one direction at a time (half duplex) or in both directions simultaneously (full duplex)
  • DV: Digital Video
  • DVB: Digital Video Broadcasting
  • DWDM: Dense Wavelength-Division MultiplexingTransmission of multiple optical signals over closely spaced wavelengths, usually in the 1550 nm region, on a single strand of fiber. See also WDM.
  • DXC: Digital Cross Connect
  • DXS: Digital Cross-Connect Switch

E

  • E-NNI: External Network-to-Network Interface
  • E-shelf: Extension shelf
  • E/O: Electrical to optical
  • E0: ITU-1 standard digital signal level 0 (64 Kbps)
  • E1: European PDH digital signal level 1 (2.048 Mbps)
  • E2E: End to end
  • E3: European PDH digital signal level 3 (34.368 Mbps)
  • E4: European PDH digital signal level 4 (139.264 Mbps)
  • EBER: Excessive Bit Error Rate
  • EBS: Emergency Broadcast System or Enhanced Business Service
  • ECB: External Connection Board. For management, found above the MECP.
  • ECC: Embedded Control (or Communications) Channel or Error Correcting Code
  • ECMP: Equal-Cost Multipath
  • ECU: External Connection Unit
  • EDF: Erbium Doped Fiber
  • EDFA: Erbium Doped Fiber Amplifier. Amplifies optical signals.
  • EDGE: Enhanced Data GSM Environment. Faster version of GSM wireless service.
  • EE: External Element
  • EFEC: Enhanced Forward Error Correction
  • EFM: Ethernet in the First Mile
  • EGP: Exterior GW Protocol
  • EIP: Electronic Information Products
  • EIR: Equipment Identity Register or Excess Information Rate
  • EIS: Ethernet Interface Switch card
  • EIS-M: Ethernet Interface Switching Module
  • ELCV: Excessive Line Code Violations
  • EMA: Embedded Management Application
  • EMB: Extended Memory Block
  • EMC: Electromagnetic Compatibility
  • EME: Externally Managed Element
  • EMF: Equipment Management Function
  • EMI: Electromagnetic Interference
  • EML: Transmitter source type interface (for STM-64/OC-192 I/O modules) or Element Management Layer (situated between the NEL and NML; controls many individual NEs)
  • EMS: Element Management System or Environmental Management System
  • E-NNI: External Network-to-Network Interface
  • EOC: End of Chain or Embedded Overhead Channel
  • EOM: End of Message
  • EoP: Ethernet over PDH
  • EoPDH: Ethernet over PDH
  • EoR: End of Record
  • EoS: Ethernet over SDH/SONET
  • EOW: Engineering Orderwire
  • EP: Endpoint
  • EPA: ESD protected area or US Environmental Protection Agency
  • EPCV: Excessive Path Code Violations
  • EPG: Electronic Program Guide
  • EPL: Ethernet Private Line
  • EPUP: Environmental Protection Use Period
  • ERM: Radio spectrum Matters
  • ERP: Ethernet Ring Protection
  • ERPS: Enterprise Resource Planning System or Ethernet Ring Protection Switching
  • ES: Errored second, Extension slot, or Electrical section
  • ESA: Errored second A (G.784)
  • ESB: Errored second B (G.784)
  • ESCON: Enterprise System Connection
  • ESD: Electrostatic Discharge
  • ESDS: Electrostatic Discharge Sensitive
  • ESI: Ethernet Synchronizing Indicator
  • ESFE: Errored Seconds Far End
  • ESNE: Errored Seconds Near End
  • ETH: Ethernet
  • Ethernet: Most widely used LAN transmission protocol, open, simple, and decentralized, for connecting computers, printers, workstations, terminals, and so on, within the same building/campus. Operates over twisted wire and coaxial cable at speeds beginning at 10 Mbps. Uses CSMA/CD techniques. See 10BaseT.
  • Ethernet LAN port: Ethernet service port
  • Ethernet WAN port: Port connecting an Ethernet switch to an SDH network via a group of virtually concatenated SDH containers
  • ETR: STM-1 SFP Electrical Transceiver
  • ETSI: European Telecommunications Standards Institute
  • ETY: Ethernet transported in layer 1
  • EVC: Ethernet Virtual Circuit
  • EVPL: Ethernet Virtual Private Line
  • EVPLAN: Ethernet Virtual Private LAN
  • EXC: Excessive Bit Errors
  • EXIM: Extension Header Mismatch
  • EXP: Experimental (Refers to EXP Mapping Values)
  • Ext: External

F

  • F channel: eNM Ethernet channel
  • FA: Fuse Alarm
  • FAS: Frame Alignment Signal
  • Fast Ethernet: 100BaseT, Ethernet at 100 Mbps
  • FAT: Flow Aware Transport
  • C: FCAPS: Fiber channel-Fault, Configuration, Accounting, Performance, and Security
  • FCM: Functional Call Management, Fiber Channel Module, or Fan Control Module
  • FCPM: Functional Component Management Plan
  • FCU: Fan Control Unit (see FCU_E2U)
  • FCS: Frame Check Sequence
  • FD: Frame Delay
  • FDB: Forwarding Database
  • FDDI: Fiber Distributed Data Interface
  • FDI: Forward Defect Indication
  • FDV: Frame Delay Variation
  • FE: Fast Ethernet, Framing (bit) Error, or Far End
  • FEBE: Far End Block Error
  • FEC: Forward Error Correction. Communication technique compensating for a noisy transmission channel. Extra information is sent along with the primary data payload to enable the receiver to correct errors in transmission.
  • FERF: Far End Receive Fail (now called RDI)
  • FIB: Forward Indicator Bit or Forwarding Information Base
  • Fiber: Thin filament of glass serving as an optical waveguide. Consists of a core and a cladding capable of carrying light signals over long distances with little attenuation. See also Optical Fiber.
  • Fiber amplifier: An all-optical device using fibers doped with erbium (or other elements) and pump lasers to increase signal output power without conversion to electrical signals.
  • FIC: Fabric Interface Control
  • FICON: Fiber Connection
  • FIO: Fabric Interface I/O, used as the prefix of L1 Fabric Interface Cards
  • FIPS: Federal Information Processing Standards, which are supported by Apollo encryption cards
  • FITL: Fiber in the Loop
  • Flat amplification: Uniform amplification of a certain wavelength band
  • Flow control: Procedure for controlling the rate of data transfer between two points in a data network
  • FM: Fault Management
  • FN: Functional Node
  • FOADM: Fixed OADM
  • FR: Frame Relay
  • Fractional E1: Carrier service offering data rates between 64 kbps and the full number of payload timeslots (31) carried by an E1 circuit, in increments of 64 kbps.
  • Fractional E3: Leasing of portions of the E3 (34.368 Mbps) bandwidth by carriers
  • Fractional services: Bandwidth available from carriers in increments of 64 kbps
  • Fractional T1: Carrier service offering data rates between 64 kbps and the full number of payload timeslots (24) carried by a T1 circuit, in increments of 64 kbps
  • Fractional T3: Leasing portions of the T3 (44.736 Mbps) bandwidth by carriers
  • Frame: Block of bits with prescribed structure. A frame may contain control and addressing information, as well as error detection (for example, CRC information) and forward error correction information. The size and composition of the frame varies according to the protocol. See also: Unframed signal.
  • Framed signal: Data stream organized in frames. See also Unframed signal.
  • Frequency: Number of pulses/cycles per second measured in units of Hertz (Hz), where 1 Hz = 1 pulse/cycle per second
  • FRR: Fast Reroute. Protection method for MPLS.
  • FRU: Field Replaceable Unit
  • FST: Fiber Storage Tray or Fiber Splice Tray (see FST)
  • FTM: Functional Topology Map
  • FTP: File Transfer Protocol
  • FTTB: Fiber to the Building/Basement
  • FTTC: Fiber to the Curb
  • FTTP: Fiber to the Premises
  • FU: Functional Unit or Fan Unit
  • Full duplex: Simultaneous transmission in both directions
  • FuN: Functional Node
  • FX: Fast Ethernet with an optical SFP interface
  • FXO: Foreign Exchange Office
  • FXS: Foreign Exchange Subscriber

G

  • Gain: Ratio of output current/voltage/power to input current/voltage/power respectively, usually expressed in dB
  • Gateway: An entrance and exit into a communications network, linking networks of different sizes and different protocols. Technically, it is an electronic repeater device that intercepts and steers electrical signals. According to the OSI model, a gateway provides mapping at all seven layers.
  • Gb: Gigabit (1 gigabit = 1,000,000,000 bits)
  • GB: Gigabyte (1 gigabyte = 1,000,000,000 bytes)
  • GbE: Gigabit Ethernet. Ethernet running at one thousand million bits per second (1 Gbps), available as shared or switched.
  • GCC: Generic conference control, General computer controls, or General Communication Channel
  • GCM: Galois Counter Mode
  • GCT: GUI Cut-Through
  • GE: Giga Ethernet
  • GEoS: Gigabit Ethernet over SDH/SONET
  • GFC: Giga Fiber Channel
  • GFEC: Generic Forward Error Correction
  • GFP: Generic Framing Procedure
  • GFP-F: Generic Framing Procedure: Frame based
  • GFP-T: Generic Framing Procedure: transparent based
  • GGSN: Gateway GPRS Support Node or Gateway Global Subscriber Number (GSN)
  • GiB: Gibibyte (1 gibibyte = 1,073,741,824 bytes)
  • GigE: Gigabit Ethernet
  • GMP: General Mapping Procedure
  • GMPLS: Generalized Multi-Protocol Label Switching
  • GNE: Gateway Network Element
  • GPON: Gigabit Passive Optical Network
  • GPRS: General Packet Radio Service
  • GRE: Generic Routing Encapsulation
  • Grooming: Consolidating or segregating traffic for efficiency. Allocating server trails to client layer connections, so grouping together client layer connections of similar/related characteristics.
  • GSM: Global System for Mobile communications
  • GSN: Global subscriber number
  • GTW: Gateway
  • GUI: Graphical User Interface
  • GW: Gateway

H

  • HA: High Availability
  • Half duplex: Two-way transmission where data can only travel in one direction at a time
  • HDLC: High-level Data Link Control
  • HDSL: High-bit-rate Digital Subscriber Line
  • HDTV: High Definition TV
  • HIO: Hybrid Input/Output (used as the prefix of various OPT99xx service cards)
  • HLC: High Level Controller
  • HLXC: High Order/Low Order Cross Connect (matrix card)
  • HO: High Order VC (VC‑4)
  • HOT: Hold-Off Time. The interval between the declaration of a signal degrade/fail condition and the initialization of a protection-switching algorithm.
  • Hot swap: The ability of a device to have parts replaced (for example, plug-in card or fan) without affecting operation.
  • HOVC: High Order Virtual Concatenation
  • HP: High Performance, High-Order Path, High priority, or High power
  • H-QoS: Hard Quality of Service
  • HSDPA: High Speed Downlink Packet Access
  • HSI: High Speed Internet
  • HSSI: High Speed Serial Interface
  • HTML: Hypertext Markup Language
  • HTTP: Hypertext Transfer Protocol
  • Hub: Center of a star topology network/cabling system
  • H-VPLS: Hierarchical Virtual Private LAN Service
  • HW: Hardware

I

  • I/F: Interface
  • I/O: Input/output
  • I-NNI: Internal Network-to-Network Interface
  • IAE: Incoming Alignment Error
  • IBC: In-Band Communication
  • ICCP: Inter Chassis Communication Protocol
  • ICMP: Internet Control Message Protocol
  • ICPs: Interconnection Panels
  • IDL: Information (Interface) Definition Language. Generic term for a language that enables a program/object written in one language to communicate with another program written in an unknown language (used in CORBA).
  • IEC: International Electrotechnical Commission or Incoming Error Count
  • IEC 825: International Electrotechnical Commission Laser Products Safety Standard
  • IEEE: Institute of Electrical and Electronics Engineers, Inc.
  • IETF: Internet Engineering Task Force
  • IG: International Gateway
  • IGMP: Internet Group Management Protocol
  • IGP: Internal (Interior) Gateway Protocol
  • ILA: Inline Amplifier. EDFA or other optical amplifier placed in the transmission line to amplify the attenuated signal before it is sent on to the next distant site.
  • ILEC: Incumbent Local Exchange Carrier
  • IMA: Inverse Multiplexing over ATM
  • IMG: In-band Management Gateway, a dedicated tri-speed Ethernet port in the Apollo chassis (see IMG Port)
  • IMI: Integrated Management Interface
  • IMM: Interactive Multimedia (or Mobile Media) or Inline Memory Module
  • IMS: Information Management System
  • IMSI: International Mobile Station Identity
  • IN: Intelligent Network
  • INAP: Intelligent Network Application Protocol
  • INF: Input Filter (unit)
  • I-NNI: Internal Network-to-Network Interface
  • INP: Intelligent Network Processor
  • Insertion loss: Loss of power resulting from the insertion of a component (like a connector or splice) into a previously continuous path
  • Interface: A mechanical or electrical link connecting two or more devices together
  • Inverse multiplexing: Method of combining individually dialed low-speed circuits into a single high-speed data stream
  • IOP: Input/Output Protection
  • IP: Internet Protocol. Network layer protocol in the TCP/IP stack originally defined in RFC 791, offering a connectionless interhost service.
  • IP address: Address assigned to a host in a TCP/IP internet (IP Version 4 uses 32-bit addresses)
  • IPDV: Instantaneous Packet Delay Variation
  • IPS: Intelligent Protection Switching
  • IPTV: Internet Protocol for TV application
  • IRB : Integrated Routing and Bridging
  • ISDN: Integrated Services Digital Network
  • IS-IS: Intermediate System to Intermediate System. Interior Gateway Protocol (IGP) providing dynamic routing between routers.
  • ISO: International Standards Organization. Entity responsible for a wide range of standards, including those relevant to networking. ISO developed the OSI reference model.
  • ISP: Internet Service Provider. Business enabling individuals and companies to connect to the internet by providing the interface to the internet backbone.
  • ITU: International Telecommunications Union. International committees of telecommunications administrations, operators, manufacturers, and scientific/industrial organizations, such as ITU‑R and ITU‑T.
  • ITU grid: ITU‑T-specified standard wavelengths for WDM optical transmission. Uses 100 GHz spacing of optical frequencies around a center frequency of 193.1 THz (1552.52 nm) for the 1550 nm window. Each standard wavelength in the grid is also referred to as an optical channel.
  • ITU-R: International Telecommunications Union: Radiocommunication
  • ITU-T: International Telecommunications Union: Telecommunication
  • IV: Initialization Vector
  • IXC: Interexchange Carrier

J

  • J2EE: Java 2 Enterprise Edition
  • Jitter: Short term time delay variations from their ideal positions in time of a timing signal (short term implies frequency variations greater than or equal to 10 Hz). Jitter is a timing phase impairment produced by regenerators and multiplexer justification schemes.
  • JMS: Java Message Service

K

  • KPI: Key Performance Indicator

L

  • L band: Wavelength range between 1570 nm and 1610 nm, used in some CWDM and DWDM applications
  • LAC: Layer 2 access concentrator
  • LACP: Link Aggregation Control Protocol
  • LAG: Link Aggregation Group
  • Lambda: WDM system channel assigned to a specific wavelength; sometimes used interchangeably with wavelength
  • LAN: Local Area Network. Communications network consisting of servers, workstations, network operating system, and communications link serving users within a confined geographical area.
  • LAPS: Link Access Procedure for SDH
  • LASER: Light Amplification by Stimulated Emission of Radiation. Light source that produces, through stimulated emission, coherent near‑monochromatic light.
  • Laser diode: Electro-optic device producing coherent light with a narrow range of wavelengths, typically centered around 780 nm, 1320 nm, or 1550 nm.
  • Launch power: Optical power a transmitter injects into a fiber, measured in dBm.
  • Layer: Concept allowing transport network functionality to be described hierarchically as successive levels/layers. Each layer is solely concerned with the generation and transfer of its characteristic information.
  • LB/LPB/LPBK: Loopback
  • LBM: Load Buffer Memory
  • LBR: Low Bit Rate or Loopback Request
  • LC: Link Control or Link Connector
  • LCAS: Link Capacity Adjustment Scheme. Equivalent to IMA in ATM.
  • LCD: Loss of Cell Delineation or Liquid Crystal Display
  • LCN: Local Communications Network
  • LCT: Local Craft Terminal
  • LD: Laser Diode
  • LDAP: Lightweight Directory Access Protocol
  • LDI: Link Down Indication
  • LDL: Logical Data Link
  • LDP: Label Distribution Protocol
  • LE: Logical Element
  • Leased line: Private communications channel leased from a common carrier
  • LEC: Local Exchange Carrier. Regional Bell operating company providing service from customer premises to its local exchange (central office) within a local geographic area.
  • LED: Light Emitting Diode. Semiconductor device emitting incoherent light from a p-n junction when biased with an electrical current in the forward direction.
  • LER: Label Edge Router
  • LF: Local Fault
  • LFD: Loss of Frame Delineation
  • LH: Long Haul
  • LIF: Logical Interface
  • Line: One or more SDH/SONET sections, including NEs, capable of accessing, generating, and processing the line overhead
  • Link: Line/channel/circuit over which data is transmitted
  • LLCF: Link Loss Carry Forward
  • LLU: Local loop unbundling
  • LMP: Link Management Protocol
  • LO: Low Order or Local Oscillator
  • LOA: Loss of Alignment
  • LOC: Loss of Clock or Loss of Connectivity
  • LOCV: Loss of Connectivity Verification
  • LOD: Loss of Data
  • LOF: Loss of Frame
  • LOL: Loss Of Light
  • LOM: Loss of Multiframe
  • LOMF: Loss of Multiframe
  • Long Haul: Long distance transmission
  • Loopback: Diagnostic test returning the transmitted signal to the transmitting device after it has passed through a network or across a particular link. The returned signal can then be compared to the transmitted one. The discrepancy between the two helps trace the fault.
  • LOP: Loss of Pointer or Low Order Path
  • LOPS: Loss of Packet Seconds
  • LOS: Loss of Signal. Condition at the receiver/maintenance signal transmitted in the physical layer overhead, indicating the receiving equipment has lost the signal.
  • LOVC: Lower Order Virtual Container or Low Order Virtual Concatenation
  • LP: Low-order Path or LightPath (LP-GbE, LP-DSR, LS-SDH/SONET clients of an OCH trail).
  • LPF: Low Pass Filter
  • LSA: Low Speed Access, Local Service Area, or Layered Scalable Architecture
  • LSD: Laser Shut Down
  • LSP: Label-Switched Path
  • LSR: Label Switch Router. Router forwarding each packet to the appropriate interface as per the label.
  • LTE: Line Terminating Equipment
  • LTI: Loss of Timing Input
  • LTM: Local Traffic Manager
  • LTO: Loss of Timing Output
  • LTR: Left to Right
  • LVD: Low Voltage Differential
  • LXC: Local Cross Connect

M

  • MA: Multiple Access or Maintenance Association
  • MAC: Media Access Control (sublayer of data link layer responsible for accessing a LAN) or Message Authentication Code
  • MACsec: Media Access Control Security
  • MAF: Management Application Function
  • MAN: Metropolitan Area Network. Communications network covering a city or suburb.
  • MB: Megabyte (1 MB = 1,000 kB)
  • MBGP: Multicast Border Gateway Protocol
  • MBP: Main Back Plane
  • Mbps: Megabits per second
  • MC: Message Center, Multipoint Controller, or Multi Chassis
  • MCC: Management Control Channels or Management Communication Channel
  • MCIPS: MCP and Central L2/L3 Packet Switch card
  • MCP: Multiplexer Control Processor or Main Control Processor
  • MCU: Microprocessor (or Multipoint) Control Unit
  • MD: Mediation Device, Multiplexing Device, or Maintenance Domain
  • MDCM: Multichannel Dispersion Compensation Module
  • MDDF: Manual Digital Distribution Frame
  • MDF: Main Distribution Frame
  • MDIX: Media Dependent Interface Crossover
  • MDU: Multidwelling Unit
  • ME: Managed Element
  • Mean launched power: Average power for a continuous valid symbol sequence coupled into a fiber
  • MECP: Main Equipment Control Panel
  • MEF: Metro Ethernet Forum
  • MEN: Metro Ethernet Network
  • MEP: Main Entry point or Maintenance Endpoint
  • MIB: Management Information Base. Formal description of a set of network objects that can be managed by using SNMP.
  • MIC: Message Integrity Check
  • MIF: Management Information Format
  • MIO: Multi-rate IO (Input/Output), used as the prefix of Apollo ODU-XC cards
  • MIP: Measured Input Power or Maintenance Intermediate Point
  • Misconnection: Situation when traffic destined for a given node is incorrectly routed to another node, and no corrective action is taken.
  • MJR LED: Major Alarm
  • MLD: Multicast Listener Discovery
  • MLM: Multi-Longitudinal Mode
  • MLT: Mechanized Loop Test
  • MM: Multimode
  • MMF: Multimode Fiber. Optical fiber in which light travels in multiple modes.
  • MMLD: Multimode Laser Diode
  • MNG PRT: Management Port
  • MNI: Mobile Network Identity or Management‑to‑Network Interface
  • MNR LED: Minor Alarm
  • MO: Managed Object
  • MOE: Metro Optical Ethernet
  • MoT: MPLS over Transport
  • MOW: Maintenance Orderwire
  • MP2MP: Multipoint to Multipoint
  • MPLS: Multiprotocol Label Switching. Set of IETF standards allowing packet flows to be switched on the basis of labels instead of the full destination address.
  • MPLS-TE: Multiprotocol Label Switching - Traffic Engineering
  • MPLS-TP: Multiprotocol Label Switching - Transport Profile
  • MRAN: Multiservice Radio Node
  • MS: Manual Switch or Multiplex/Multiplexer Section (trail between and including two multiplex section trail termination functions)
  • MS/RS: Multiplexer Section/Regenerator Section
  • MSA: Multiplex Section Adaptation
  • MSAG: Multiservice Access Gateway
  • MS-AIS: Multiplex Section Alarm Indication Signal
  • MSAN: Multiservice Access Node or Multiservice Access Network
  • MSAS: Multiservice Aggregation Switch
  • MSC: Mobile Switching Center
  • MSE: Main Switch Equipment
  • MS-EBER: Multiplex Section Excessive Bit Error Rate
  • MSEE: Multiplex Section Excessive Error
  • MSER: Multiservice Edge Router
  • MSI: Message Structure Identifier
  • MSIM: Multiplex Structure Identifier Mismatch
  • MSM: Multiservice Module
  • MSO: Multiservice Operator
  • MSOH: Multiplex Section Overhead
  • MSP: Multiplex section protection
  • MS-P: Manual Switch to Protection
  • MSPA: Multiplex Section Protection Adaptation
  • MSP-L: Linear Multiplex Section Protection
  • MSPP: Multiservice Provisioning Platform
  • MSPT: Multiplex Section Protection Termination
  • MSPW: Multi Segment Pseudowire
  • MS-RDI: Multiplex Section Remote Defect Indication
  • MS-SPRing: Multiplex Section Shared Protection Ring
  • MSTI: Multi (or Multiple) Spanning Tree Instance
  • MSTP: Multiservice Transport Platform, Multiplexer Section Termination Point, or Multiple Spanning Tree Protocol
  • MTBF: Mean Time Between Failures
  • MTIE: Maximum Time Interval Error. Maximum peak-to-peak delay variation of a given timing signal within an observation period compared to an ideal timing signal within the same period. Measured for all observation periods of the same length within a specified time.
  • MTNM: Multitechnology Network Management. Extensive interface enabling communications between different network management products ("northbound interface") for SDH, SONET, DWDM, and ATM networks. Previously known as SSIM.
  • MTOSI: Multitechnology Operations System Interface
  • MTTF: Mean Time to Failure
  • MTTR: Mean Time to Repair
  • MTU: Maximum Transfer Unit or Maximum Transmission Unit (largest frame size that can be transmitted over the network)
  • MU: Main Unit
  • Multiframe: Structure composed of multiple frames
  • Multimode: Optical fiber allowing more than one mode of light signal transmission
  • Multimode dispersion: Dispersion resulting from different transit lengths of different propagating modes in a multimode optical fiber. Also called modal dispersion.
  • Multiplexer: Device merging several low-speed transmissions into one high-speed transmission, and vice versa
  • Multipoint: Connection of more than two locations (compare point-to-point connection)
  • Mux: Multiplexer. Device merging several low-speed transmissions into one high-speed transmission, and vice versa.
  • MWR: Microwave Radio
  • MXC: Main XC and Control card
  • MXC4X: Cross-connect, Timing, and Control card
  • MXD: MUX/DEMUX, used as the prefix of MUX/DEMUX Cards

N

  • Narrowband: Generic designation for services requiring up to 2 Mbps (SDH)/1.5 Mbps (SONET) transport capacity
  • NB: Narrowband
  • NB-DXC: Narrowband Digital Cross Connect
  • NBI: Northbound Interface - connects either the EMS or LightSOFT to the OSS.
  • NC: Network Connection
  • NE: Network Element or Near End
  • NEBS: Network Equipment Building System
  • NEL: Network Element Layer. Lowest management layer under EML and NML. Constitutes the embedded agent software of NEs (M.3010).
  • NES: Near end Errored Second
  • Network topology: Configurations that can be adopted in building networks, such as a ring, bus, star, or mesh
  • NFS: Network File System
  • NFV: Network Function Virtualization
  • NG: Next Generation
  • NGN: Next Generation Network
  • NH: Network Header
  • NI: Network Interface
  • NIC: Network Interface Card
  • NIM: Nonintrusive Monitoring
  • NLRI: Network Layer Reachability Information

  • NM: Network Management
  • NML: Network Management Layer. Highest management layer, over NEL and EML. Controls all main network management functions (M.3010).
  • NMS: Network Management System, between TMN and EMS in the management hierarchy
  • NNI: Network-to-Network Interface
  • NOC: Network Operations Center, Network Operator Control, or Number of Channels
  • Node: Network junction or connection point
  • NP: Number portability, Network performance, or Network Provider
  • NPJ: Negative Pointer Justification
  • NPT: Native Packet Transport
  • NPU: Network Processing Unit
  • NRZ: Non Return to Zero
  • NSP: Node Switch Processor
  • NT: Network Terminal
  • NT (U): Network Termination (Unit)
  • NTP: Network Time Protocol
  • NTR: Net Time Reference
  • NuT: Nonpreemptable Unprotected Traffic
  • NVM: Nonvolatile Memory
  • NVRAM: Nonvolatile Random Access Memory

O

  • O/E: Optical to Electrical
  • OA: Optical Amplifier. Device amplifying an input optical signal and converting it to an electrical form. Used as the prefix of various Apollo optical amplifiers.
  • OA&M/OAM: Operations, administration, and maintenance
  • OADM: Optical Add-Drop Multiplexer. Receives simultaneous signals at different wavelengths sent down an optical fiber, drops one, and adds a new signal at the same wavelength. See OADM Cards.
  • OAM&P: Operation, administration, maintenance, and provisioning
  • OBC: On-Band Computer, On-Board Controller, or  Optical Base Cards (see OBC for Neptune OBC cards)
  • OC: Optical Carrier. A SONET optical signal (transmission speed).
  • OC-1: Optical Carrier level 1, 51.84 Mbps
  • OC-12: Optical Carrier level 12, 622.08 Mbps
  • OC-192: Optical Carrier level 192, 9.953 Gbps
  • OC-256: Optical Carrier level 256, 13.2192 Gbps
  • OC-3: Optical Carrier level 3, 155.52 Mbps
  • OC-48: Optical Carrier level 48, 2.488 Gbps
  • OCH: Optical Channel
  • OCHP: Optical Channel Protection
  • OC-n: SONET Optical Carrier level n
  • OCN: Object Creation Notification in MTNM
  • OCU: Optical Connection Unit
  • OCWR: Optical Continuous Wave Reflectometer
  • OCXO: Oven Controlled Crystal Oscillator
  • OD: Optical Demultiplexer
  • ODBC: Open Database Connectivity
  • ODF: Optical Distribution Frame
  • ODN: Object Deletion Notification in MTNM
  • ODU: Optical Data Unit
  • ODUOOB: Optical Data Unit Out-of-Band
  • ODUCn: Optical Data Unit of n*100G[i.e. “C” stands for the romic digit for 100G]
  • OEO: Optical to Electrical to Optical
  • OF: Optical Fiber
  • OFA: Optical Fiber Amplifier
  • OFR: Optical Fiber Regenerator
  • OFS: Out of Frames Seconds
  • OH: Overhead
  • OHA: Overhead Access. Function providing access to transmission overhead functions.
  • OHU: Overhead Unit
  • OLP: Optical Line Protection
  • OLR: Overall Loudness Rating or Off-Line Reader (or recovery)
  • OLT: Optical Line Terminal or On-line test
  • OM: Optical Multiplexer or Optical Module
  • OMCI: Operation, Management, and Control Interface
  • OMG: Object Management Group
  • OMI: Optical Management Interface. Supervisory channel using a separate wavelength to manage NEs, usually defined as a wavelength of 1510 nm (G.694).
  • OMLT: Optimized Multi-Layer Transport
  • OMP: Optical Multiplex Protection
  • OMS: Optical Multiplex Section. Section of a DWDM system that incorporates an optical add/drop multiplexer.
  • OMSP: Optical Multiplex Section Protection
  • OMT: Optical Multiplexing Terminal
  • OMTX: Optical Multiplexing Terminal
  • ON: Optical Network
  • ONCP: Optimized Network Communications Protocol or Optical Network Control Parameters
  • ONCPIMG: Optical Network Control Protocol In-band Management Gateway, a proprietary protocol for exchanging actual optical parameters between NEs that are adjacent in the WDM data plane
  • ONE: Optical Network Element
  • ONN: Optical Network Node or Optical Network Manager
  • ONT: Optical Network Terminal
  • ONU: Optical Network Unit
  • OOBONCP: Out-of-Band Optical Network Control Protocol, a proprietary protocol for exchanging actual optical parameters between NEs that are adjacent in the WDM data plane
  • OOF: Out of Frame
  • OOM: Out of Margin
  • OOR: Out of Range
  • OP: Optical Path or Optical Power
  • OPA: Optical Preamplifier (see Apollo optical amplifiers)
  • OPB: Optical Power Booster or Optical Processor Blade
  • OPEX: Operating Expenses
  • OPI: Optical Physical Interface
  • OPM: Optical Power Meter or Optical Performance Monitor
  • OPP - Optical Patch Panel
  • OPS: Optical Physical Section
  • Optical amplifier: A device that amplifies an input optical signal without converting it into electrical form. The best developed are based on optical fibers doped with the rare earth element erbium.
  • Optical carrier: Optical signal used to carry information. Also a carrier rate specified in the SONET standard.
  • Optical channel: Channel used for carrying optical communications. Also a channel using a wavelength in the ITU grid. See ITU grid.
  • Optical channel spacing: Separation, usually expressed as a frequency, between wavelengths of adjacent WDM channels
  • Optical fiber: Fiber made of dielectric material and consisting of a core, light carrying medium, and cladding (protective layer). Allows total internal reflection of the light for propagation.
  • Optical loss: Amount of optical power lost as light transmitted through fiber, splices, couplers, and so on
  • Optical power: Amount of radiant energy per unit time; may be expressed in linear units of Watts or on a logarithmic scale in dBm
  • Optical pump laser: Shorter wavelength laser that is used to pump a length of fiber with energy, so providing amplification at one or more longer wavelengths. See also EDFA.
  • Optical switch: Device that routes an optical signal from one or more input ports to one or more output ports
  • OPU: Optical Channel Payload Unit
  • ORB: Object Request Broker
  • Orderwire: Dedicated voice channel for maintenance supported by overhead bytes E1/E2
  • ORL: Optical Return Loss
  • OS: Operating System or Optical section
  • OSA: Optical Spectrum Analyzer or Optical Signal Analyzer
  • OSC: Optical Supervisory Channel (see Optical Supervisory Channel Cards)
  • OSI: Open Standard Interconnect. 7-layer model specified by ISO for defining the operation of communications networks.
  • OSMC: OTN Synchronization Message Channel (introduced in OTUCn)
  • OSn: Optical Section layer, level n (n = 1, 4, 16)
  • OSN: Optical Service Network
  • OSNR: Optical Signal-to-Noise Ratio
  • OSPF: Open Shortest Path First
  • OSS: Operations Support System
  • OT: Optical Transmitter
  • OTDM: Optical Time Division Multiplexing
  • OTDR: Optical Time Domain Reflectometer (see OTDR)
  • OTGBE: Optical Transceiver GE
  • OTH: Optical Transport Hierarchy (G.709)
  • OTM: Optical terminal multiplexer or Optical Transport Module (G.709)
  • OTN: Optical Transport Network, which is the basis of the Apollo platform
  • OTP: One-Time Programmable transceiver type, One-Time Password
  • OTR: Optical Transponder
  • OTS: Optical Transmission Section
  • OTU: Optical Transport Unit or Optical Transmit Unit
  • OTUCn: Optical Transport Unit of n x 100G [i.e. "C" stands for the romic digit for 100]
  • OTUk: Completely standardized Optical channel Transport Unit-k
  • OTUkV: Functionally standardized Optical channel Transport Unit-k
  • Overhead: Extra bits in a digital stream used to carry information other than traffic signals
  • OW: Orderwire
  • OXC: Optical Cross Connect

P

  • P2MP: Point to Multipoint
  • P2P: Point to Point
  • PABX: Private automatic branch exchange
  • Packet: Block of data used for transmission in packet-switched systems. The terms frame, packet, and datagram are used synonymously.
  • Packet-OTS (P-OTS): Packet-Optical Transport System
  • PAD: Packet Assembly Device
  • Path: Logical connection between a point where a service in a VC (SDH), STS, or VC (SONET) is multiplexed and the point where it is demultiplexed
  • Payload: Part of a data field, block, or stream being processed or transported that represents information useful to the user (as opposed to system overhead information). Payload may include additional user-requested network management and accounting information. In SONET, the STS-1 signal is divided into a transport overhead section and an information section (similar to signaling and data). See SPE (Synchronous Payload Envelope) for a description of what is found in the payload.
  • PB: Provider Bridge
  • PBS: Portable Base Station
  • PC: Private Circuit or Personal Computer
  • PCM: Pulse Code Modulation
  • PCN: Personal Communications Network
  • PCO: Power Control Object
  • PCP: Peripheral Call Process or Primary Control Program
  • PD: Photodetector
  • PDH: Plesiochronous Digital Hierarchy
  • PDI: Payload Defect Indication
  • PDU: Power Distribution Unit 
  • PDV: Path Delay Value
  • PE: Provider Edge
  • PELES: Power Equalization for Lightwave Enabled Servers
  • PFM: Pulse Frequency Modulation or Power Filter Module
  • PG: Peripheral Gateway
  • PGO: Protection Group Object
  • Photodetector: Opto-electronic transducer such as a PIN photodiode or avalanche photodiode
  • Photodiode: Diode designed to produce photocurrent by absorbing light
  • Photon: Quantum of electromagnetic energy; particle of light
  • PHY: Physical layer
  • PIM: PDH I/O Module or Protocol-Independent Multicast
  • PIN: Packet Identification Number or Personal Identification Number
  • PIO: PDH Input/Output card
  • PIR: Peak Information Rate
  • PJE: Pointer Justification Event
  • PL: Partial Loss
  • PLM: Payload Label Mismatch
  • PLR: Packet Loss Rate
  • PLTV: Pause Live TV
  • PM: Performance Monitoring
  • PMA: Physical Medium Attachment
  • PMD: Polar Mode Dispersion
  • PME: PDH Module for E1, used as the prefix of various Neptune PDH/SDH cards
  • PN: Physical Node
  • PNNI: Private Network-to-Network Interface. Routing information protocol enabling extremely scalable full functionality.
  • POA: Packet Optical Access
  • POC: Point of Contact
  • PoE: Power over Ethernet
  • POH: Path Overhead. Overhead accessed, generated, and processed by path terminating equipment.
  • Point to point: Connection established between two specific locations
  • Pointer: Part of the overhead that locates a floating payload structure
  • PON: Passive Optical Network
  • POP: Point of Presence. Point at which a line from a long distance carrier connects to the line of the local telephone company, or to the user if the local company is not involved.
  • POS: Packet over SDH/SONET. Technology in which IP packets are mapped into SDH/SONET frames.
  • POTS: Plain Old Telephone Service
  • Power budget: Difference between the amount of power (measured in dB) that a piece of transmission equipment launches into a fiber and the amount of power that the detector requires to operate satisfactorily.
  • PPC: Power per Channel
  • PPE: Personal protective equipment or Packet Processing Element
  • PPI: PDH Physical Interface
  • PPJ: Positive Pointer Justification
  • PPP: Point-to-Point Protocol
  • PPPoA: Point-to-Point Protocol over ATM
  • PPPoE: Point-to-Point Protocol over Ethernet
  • PPS: Packets per Second or Precise Positioning Service
  • PPV: Pay per view
  • PRBS: Pseudo Random Binary Sequence
  • PRC: Primary reference clock. High-precision clock used as a reference for SDH/SONET systems, highest in the timing hierarchy before SSU and SEC.
  • Preamp: Optical amplifier at receiver site
  • Protocol: Set of rules governing the information flow within a communications infrastructure
  • PS: Power Supply or Path Selector (selects the path of signals arriving from primary and secondary nodes in two‑node interworking rings (one applies to MS-SPRing and the other to SNPC (G.842)).
  • PSC: Packet scheduling or Protection State Coordination Protocol
  • PSD: Power Spectral Density
  • PSE: Power Sourcing Equipment
  • PSN: Packet Switched Network. Communications network using packet switching technology.
  • PSTN: Public Switched Telephone Network. Generic term for networks that provide public telephone switching service.
  • PTI: Payload Type Indicator
  • PTIM: Payload Type Indicator Mismatch alarm
  • PTP: Point to Point, Precision Timing Protocol, Physical Termination Point
  • PTT: Postal Telegraph and Telephone
  • Pumping Laser: Laser used to transfer energy to EDFA
  • PVC: Permanent Virtual Circuit. Software-defined logical connection in a frame relay network; enables definition of bandwidths and logical connections between endpoints.
  • PW: Pseudowire or Password
  • PWE3: Pseudowire emulation edge to edge
  • PWR: Pseudowire Redundancy
  • PXF: Parallel express forwarding

Q

  • Q: Connection interface in SDH management network (G.773)
  • QH: Quarter hour
  • QinQ: Ethernet Provider Bridge
  • QL: Quality Level
  • QoE: Quality of Experience
  • QoS: Quality of Service. Ability to define a level of performance in a communications system.
  • QRSS: Quasi Random Signal Source
  • QSFP: Quad Small Form-factor Pluggable

R

  • RADIUS: Remote Authentication Dial in User Service
  • RAI: Remote Alarm Indication
  • RAID: Redundant Array of Inexpensive (or Independent) Disks. Provides a means for storing the same data in different places (redundantly) on multiple hard disks.
  • RAM: Random Access Memory
  • RAN: Radio Access Network
  • RAP: Rack Alarm Panel or Remote Access Point
  • RAS: Remote Access Server
  • RBOC: Regional Bell Operating Company
  • RCC: Radio Common Carrier. Carrier engaged in the provision of public mobile service.
  • RCP: Routing Control Processor or Remote Control Profile
  • RD: Received Data, Routing Domain, Route Descriptor, Route Distinguisher, or Request Disconnect
  • RDI: Remote Defect Indication (formerly FERF)
  • RDR: Remote Database Replication
  • Receiver: Device at the destination end that includes a detector and signal processing electronics for performing optical to electrical conversion
  • RED: Random Early Discard or Random Early Detection
  • Regeneration: Method of boosting a digital signal
  • REI: Remote Error Indication (formerly FEBE)
  • Repeater: Device that boosts power in a long distance system by detecting the signal, amplifying it electronically, and then retransmitting it with another optical device, thus resulting in an increase in the achievable transmission path
  • REST API: Represented State Transfer API
  • RF: Remote Fault
  • RFI: Remote Failure Indication or Radiofrequency Interference
  • RI: Refractive Index
  • RIB: Routing Information Base
  • Ring: Collection of nodes forming a closed loop whereby each node is connected to two adjacent nodes via a duplex communications facility
  • Ring topology: Layout scheme in which the network forms a closed loop with the devices attached into the ring
  • RIP: Routing Information Protocol
  • RLP: Radio Link Protocol
  • RMI: Resource Manager Interface or Route monitoring information
  • RMS: Root Mean Square or Remote Monitoring Station
  • RNC: Radio Network Controller
  • ROADM: Reconfigurable Optical Add-Drop Multiplexer
  • RoHS: Restriction of Hazardous Substances
  • ROI: Return on Investment
  • ROSE: Remote Operation Service Element (Application layer)
  • Route: Path through an internetwork
  • RP: Rendezvous (reference) point or Routing Protocol
  • RPL: Remote Procedure Load, Radio Physical Layer, or Requested Privilege Level
  • RPR: Resilient Packet Ring
  • RPT: Repeater (transponder) card
  • RS: Regenerator section
  • RSA: Rivest Shamir & Adleman (encryption)
  • RS-TIM: Regenerator Section Trace Identifier Mismatch
  • RSTP: Rapid Spanning Tree Protocol
  • RSTP-TE: Rapid Spanning Tree Protocol - Traffic Engineering
  • RSU: Remote Switching Unit
  • RSVP: Reservation Protocol or Resource Reservation Protocol
  • RSVP-TE: Resource Reservation Protocol - Traffic Engineering
  • RT: Route Target
  • RTC: Real-Time Clock
  • RTP: Rapid Transport Protocol
  • Rx: Receive, receiver, reception
  • RX: Receive signal
  • RZ: Return to Zero
  • RZ-DQPSK: Zero Differential Quadrature Phase Shift Keying

S

  • S band: Wavelength range between 1485 nm and 1520 nm used in some CWDM and DWDM applications
  • S-d: Source-destination
  • S-GW: Serving Gateway. Device or assembly that coordinates the control and adapts data transmission between a device and a system.
  • S-VLAN: Subscriber Virtual Local Area Network
  • SAM: SDH Aggregate Module
  • SAN: Storage Area Network
  • SAS: Severely Errored Frame/Alarm Indication Signal Seconds
  • SATE: Stored Attenuation
  • SAToP: Structure-Agnostic TDM over Packet

  • SB DCS: Superband Digital Cross-Connect System
  • SBS: Simulated Brillouin Scattering
  • SBU: Strategic Business Unit
  • SC or LC: Optical transceiver connector
  • SCADA: Supervisory Control and Data Acquisition
  • Scattering: Direction change of light rays/photons after striking small particles
  • SCIO: Subsystem Computer Input/Output
  • SCSI: Small Computer System Interface
  • SD: Signal Degrade
  • SDH: Synchronous Digital Hierarchy. Hierarchical set of digital transport structures standardized for the transport of suitably adapted payloads over physical transmission networks.
  • SDI: Serial Digital Interface for video signals or SDH Physical Interface
  • SDM-1: Syncom 155.52 Mbps synchronous digital multiplexer
  • SDM-16: Syncom 2488.32 Mbps synchronous digital multiplexer
  • SD-P: Signal Degrade Protection
  • SDR: SDH Regenerator
  • SDRAM: Synchronous Dynamic Random Access Memory
  • SDXC: Synchronous Digital Cross Connect
  • SEC: SDH/SONET Equipment Clock
  • Section: Span between two NEs capable of accessing, generating, and processing only section overhead
  • SELCV: Severe Excessive Line Code Violations
  • SELT: Single-Ended Loop Testing
  • SELV: Separated or Safety Extra-Low Voltage
  • SEMF: Synchronous Equipment Management Function
  • Serial interface: Hardware for sending and receiving data one bit at a time
  • SES: Severely Errored Second
  • SETS: Synchronous Equipment Timing Source (G.826)
  • SF: Signal Fail
  • SF/SD: Signal Failure/Signal Degradation
  • SFF: Small Form Factor
  • SFP: Small Form-factor Pluggable
  • SFTP: Secure File Transfer Protocol

  • SFU: Store and Forward Unit or Special Function Unit
  • SGSN: Serving GPRS Support Node
  • SGW: Service Gateway
  • SH: Short Haul
  • Shared protection: Protection architecture using m protection entities shared among n working entities (m:n). The protection entities may also be used to carry extra traffic when not used for protection.
  • SHDSL: Single-pair High-Speed DSL
  • SHG: Segmented Hypergraphic
  • SIM: SDH/SONET I/O Module
  • Single-ended maintenance: Ability to access NEs at remote locations for maintenance purposes
  • Single-mode fiber: Optical fiber with a small core diameter (typically 9 mm), in which only a single mode (fundamental) is capable of propagation
  • SIO: Synchronous Input/Output card or SDH Input/Output card
  • SIP: Session Initiation Protocol
  • SLA: Service Level Agreement
  • SLC: Span Loss Change
  • SLIP: Serial Line Internet Protocol. TCP/IP protocol for using a regular (serial) telephone line and modem to connect a computer as host over IP.
  • SLM: Signal Label Mismatch, Synthetic Loss Measurement, or Single Longitudinal Mode laser (injection laser diode with a single dominant longitudinal mode).
  • SLMF: Signal Label Match Fail
  • SLRG: Shared Link Risk Group
  • SMB: Server Message Block or Small and Medium Business
  • SMD: SDH Module Dual (2 interfaces), used as the prefix of various Neptune PDH/SDH cards
  • SML: Service Management Layer
  • SMN: SDH Management Network
  • SMS: Short Message Service or SDH Module Single (one interface) (used as the prefix of various Neptune PDH/SDH cards)
  • SMQ: SDH Module Quad (4 interfaces), used as the prefix of various Neptune PDH/SDH cards
  • SNC: Subnetwork Connection or Synchronous Network Clock
  • SNC/I: Subnetwork connection protection with inherent monitoring
  • SNC/N: Subnetwork connection protection with nonintrusive monitoring
  • SNC/S: Subnetwork connection protection with sublayer monitoring
  • SNCP: Subnetwork Connection Protection
  • SNH: Subnetwork Handler
  • Snk: Sink
  • SNMP: Simple Network Management Protocol
  • SNR: Signal-to-Noise Ratio
  • SNTP: Simple Network Time Protocol
  • So: Source
  • SO: Section Overhead
  • SOA: Service-Oriented Architecture or Semiconductor Optical Amplifier: laser diode without end mirrors coupled to fibers on both ends. Light coming through either fiber is amplified by a single pass through the laser diode).
  • SOAP: Simple Object Access Protocol
  • SOC: Start of Chain
  • SOH: Section Overhead
  • SOHO: Small Office Home Office
  • SONET: Synchronous Optical Network. Standard for optical transport used in the United States, Canada, Korea, Hong Kong, and elsewhere, that defines optical carrier levels and their electrically equivalent synchronous transport signals.
  • SP: Service Provider
  • SPA: Single Point of Access or Service Provider Application
  • Span: Set of multiplex sections between two adjacent nodes on a ring
  • SPE: Signal Processing Equipment or Synchronous Payload Envelope, which is a major portion of the SONET frame format used to carry the STS-1 signal divided into an information payload section and a transport overhead system. Used to address three payload structures: direct to STS-1 line rate multiplexing, asynchronous DS-3 multiplexing, and synchronous DS-3 multiplexing.
  • SPF: Shortest Path First
  • SPI: SDH/SONET Physical Interface
  • Splice/Splicing: Permanent connection of two optical fibers by fusion or mechanical means
  • Splitter: Passive device dividing optical power from a common input among several output fibers
  • SPLTB: Split B access
  • SPM: Self-Phase Modulation (G.694)
  • SPO: Specific Payload Object
  • SPOC: Single Point of Contact
  • SPOF: Single Point of Failure
  • SPP: Sliced Packet Port
  • SPRing: Shared Protection Ring
  • SPU: SDU Processing Unit
  • SQL: Structured Query Language
  • SQM: Sequence Number Mismatch
  • SR: Short Reach
  • SRA: Selective Routing Arrangement
  • SRAM: Static Random Access Memory
  • Src: Source
  • SRGB: Segment Routing Global Block
  • SRLG: Shared Risk Link Group
  • SRTP: Secure Reliable Transfer Protocol
  • SSF: Server Signal Fail
  • SSH: Secure Socket Shell
  • SSIM: SDH/SONET Interface Module
  • SSM: Synchronization Status Marker (protocol) or Synchronization Status Message
  • SSP: Storage Service Provider
  • SSU: Synchronization Supply Unit
  • SSW: Serving Switch
  • Star coupler: Coupler in which power at any input port is distributed to all output ports
  • Star network: Network in which all terminals are connected through a single point like a star coupler or concentrator
  • Star topology: Network layout or design in which each node is connected to a central hub
  • STB: Set-Top Box
  • STM: Synchronous Transfer Mode or Synchronous Transport Module: structure in SDH transmission hierarchy. STM‑1 is the SDH base level transmission rate, 155.52 Mbps. Higher rates include STM‑4, STM‑16, STM‑64, and STM‑256.
  • STM-1: Synchronous Transport Module 1, 155.52 Mbps
  • STM-16: Synchronous Transport Module 16, 2488.32 Mbps
  • STM-256: Synchronous Transport Module 256, 39813.12 Mbps
  • STM-4: Synchronous Transport Module 4, 622.08 Mbps
  • STM-64: Synchronous Transport Module 64, 9953.28 Mbps
  • STM-n: Synchronous Transport Module level n (n = 1, 4, 16, 64, 256)
  • STM-nc: Synchronous Transport Module level n, concatenated
  • STP: Spanning Tree Protocol
  • STS: Synchronous Transport Signal
  • STS-1: Synchronous Transport Signal 1, 51.84 Mbps
  • STS-3: Synchronous Transport Signal 3, 155.52 Mbps
  • STS-n: Synchronous Transport Signal, level n
  • SU: Slot Unit
  • SVC: Supervisory Channel or Switched Virtual Circuit (temporary virtual circuit established and maintained only for duration of data)
  • SW: Software
  • Switch: Equipment connecting and distributing communications between a trunk line/backbone and individual nodes
  • Switching: Temporary connection (fundamental difference between circuit and packet switching)
  • Synchronous: Network with transmission system payloads synchronized to a master (network) clock, and traced to a reference clock

T

  • T::NMS: T::DAX Network Management System
  • T0: Digital transmission facility operating at DS‑0 rate (64 kbps)
  • T1: Digital transmission facility operating at DS‑1 rate (1.544 Mbps)
  • T3: Digital transmission facility operating at DS‑3 rate (44.736 Mbps)
  • TAC: Type Approval Code
  • TACACS: Terminal Access Controller Access Control System
  • TAD: Test Access Device
  • Tandem connection: Arbitrary series of contiguous link and/or subnetwork connections
  • TAP: Test Access Port
  • TAQ: Trail Acquisition
  • TC: Tandem Connection or Transient Condition
  • TCA: Threshold Crossing Alarm in MTNM
  • T-carrier: US standard for digital transmission lines. The two most common are T1, which transmits DS‑1 formatted data at 1.544 Mbps, and T3, which transmits DS‑3 formatted data at 44.736 Mbps.
  • TCI: Trail Consistency Indicator
  • TCM: Tandem Connection Monitor/Monitoring
  • TCN: Throughput Class Negotiation or Telecommunications Network
  • TCO: Total Cost of Ownership
  • TCP: Terminal Connection Point or Transmission Control Protocol
  • TCP/IP: Transmission Control Protocol/Internet Protocol. Common name for the suite of protocols developed by the US Department of Defense in the 1970s to support the construction of worldwide internetworks. TCP and IP are two of the best-known protocols in the suite. TCP corresponds to Layer 4 (transport) of the OSI reference model and provides reliable transmission of data. IP corresponds to Layer 3 (network) of the OSI reference model and provides connectionless datagram service.
  • TCPM: Tandem Connection Performance Monitoring
  • TCXO: Temperature Controlled Crystal Oscillator
  • TDC: Tape Data Controller, Transparent Data channel, Tolerance Dispersion Compensation, or Tunable Dispersion Compensation
  • TDM: Time Division Multiplexing. Technology that apportions time available on its composite link between channels, interleaving data from successive channels. Input is therefore taken from each source in turn, so maximizing bandwidth usage of digital channels.
  • TE: Traffic Engineering
  • TEIM: Trail Export Import (XML)
  • TEQ: Test Equipment
  • TEX: Tributary Expansion card
  • TF: Test facility, Terminal function, or Transmit failure
  • TFA: Transparent File Access or Tunable Filter Array
  • TG: Timing Generator
  • Throughput: Speed at which a computer processes data
  • TIOMR: TDM In-Out Multi Rate. An OPT99XX Apollo card (see TIOMR_32).
  • TIM: Trace Identifier Mismatch
  • TISPAN: Telecom and Internet Services and Protocols for Advanced Networks
  • TIU: Tributary Interface Unit
  • TL: Transmission Level or Total Loss
  • TLS: Transparent LAN Service
  • TM: Terminal Multiplexer, Transverse Magnetic, Transmission Matrix, or Transponder and Muxponder (used as the prefix of various OPT96xx service cards).
  • TMF: Telemanagement Forum
  • TMN: Telecommunications Management Network
  • TMSE: Timing & Multi Service E1 card
  • TMU: Timing Unit
  • TN: Telephone Number
  • TNV: Telecommunications Network Voltage
  • TO: Telecommunications Operator
  • ToD: Time of Day, Topology On Demand
  • ToS: Type of Service
  • TP: Termination Point
  • TPM: Tributary Protection Module
  • TPU: Tributary Protection Unit
  • TR: Task Register, Technical (or Threshold) Report, or Transponder (used as the prefix of various OPT96xx service cards).
  • Trail: Transport entity consisting of an associated pair of unidirectional links capable of simultaneously transferring information in opposite directions between their respective inputs and outputs
  • Transceiver: Device performing telecommunications transmission and receiving functions
  • Transmitter: Electronic package converting a signal carrying electronic information to a signal suitable for transmission over a certain media. For example, an optical transmitter converts information in a form suitable for transmission over fiber.
  • Transponder: In a WDM system, module receiving an input signal, amplifying and converting it to a wavelength for optical multiplexing with other wavelengths. Allows PM.
  • Transport network: Functional resources of a network conveying user information between locations
  • Triple play: Triple play services - video, voice, data
  • TRP: Transponder
  • Trunk: Communications channel between two points. Usually refers to large bandwidth telephone channels between switching centers that handle many simultaneous voice and data signals.
  • TS: Timeslot or Tributary Slot
  • TSC: Tunnel Segment Consistency
  • TSF: Trail Signal Fail. Provides indication to Ethernet clients of SDH/SONET network failure.
  • TSGR: Transport systems generic requirements
  • TSI: Time Slot Interchange
  • TSSI: Time Slot Sequence Integrity
  • TSTV: Time Shift Television
  • TSU: Telephone Signal Unit or Traffic Switching Unit
  • TTI: Trail Trace Identifier
  • TTL: Transistor-Transistor Logic or Time to Live (number of NEs DCC packets that can pass through before being terminated)
  • TTP: Tributary Termination Point or Trail Termination Point
  • TU: Termination Unit or Tributary Unit: Information structure providing adaptation between the low order and the high order path layer. Contains the virtual container (VC) plus a tributary unit pointer.
  • TU-AIS/AIS-V: TU Alarm Indication Signal/VT Alarm Indication Signal
  • TU-BER: Tributary Bit Error Rate
  • TUG: Tributary Unit Group. Contains several tributary units.
  • TU-LOP/LOP-V: TU Loss of Pointer/VT Loss of Pointer
  • TUPP: Tributary Unit Payload Processor
  • TVCXO: Temperature Voltage Controlled Crystal Oscillator or Temperature-compensated Voltage Controlled Crystal Oscillator
  • TWAMP: Two-Way Active Measurement Protocol
  • Twisted pair: Two insulated copper wires twisted together, with twists/lays of varying length to reduce potential signal interference between the pairs. The most common medium for electrically connecting phones, computers, and terminals.
  • Tx: Transmission/transmitter/transmit
  • TX: Transmit signal

U

  • UAS: Unavailable Seconds
  • UAT: Unavailable Time (G.784)
  • UBR: Unspecified Bit Rate (ATM QoS class)
  • UCE: Un Correctable Errors
  • UDP: User Datagram Protocol
  • UE: User Element
  • UI: Unit Interval
  • ULL: Ultra Low Loss or Unbundled Local Loop
  • UME: Unmanaged Element
  • UMTS: Universal Mobile Telecommunications System
  • UNEQ: Unequipped
  • UNEQP: Unequipped low‑order path
  • Unframed signal: Bit stream with unknown or ignored frame structure. See also Framed signal.
  • UNI: User to Network Interface
  • Unidirectional: Operating in one direction only
  • UPC: Usage Parameter Control. Set of actions taken by the network to monitor and control traffic at the end-system access.
  • UPI: User Payload Identifier
  • UPIM: User Payload Identifier Mismatch alarm
  • UPS: Uninterruptible Power Supply
  • UPSR: Unidirectional Path Switched Ring. Protection scheme used in SONET rings in which traffic is sent in one direction on one of the two rings and the second ring is reserved for redundancy.
  • USF: User Signal Fail
  • USHR: Unidirectional Self-Healing Ring. MS-USHR is another name for MS-SPRing.
  • UTC: Universal Test Client, Unit test case, or Utilities Telecommunication Council
  • UTP: Unshielded Twisted Pair of cables

V

  • VBR: Variable Bit Rate (ATM QoS class, can be rt (real time) or nrt)
  • VC: Virtual Connection or Virtual Container. SDH defines a number of containers, each corresponding to an existing plesiochronous rate. Information from a plesiochronous signal is mapped into the relevant container along with control information known as the “path overhead”.
  • VC-12: Virtual Container 12, 2.048 Mbps (used on low‑order path)
  • VC-3: Virtual Container 3 (used on low‑order path)
  • VC-4: Virtual Container 4 (used on high‑order path)
  • VCAT: Virtual Concatenation
  • VCC: Voltage at Common Collector
  • VCG: Virtual Concatenation Group
  • VCI: Virtual Channel Identifier
  • VC-n: Virtual Container, level n
  • VCO: Voltage Control Oscillator. Part of the phase control loops for clock synchronization.
  • VCXO: Voltage Controlled Crystal Oscillator
  • VDF: Voice-Frequency Distribution Frame
  • VID: Video Identifier
  • VLAN: Virtual Local Area Network
  • VLL: Virtual Leased Line
  • VMUX: Variable attenuation multiplexer
  • VNC: Virtual Network Computing
  • VNF: Virtualized Network Function
  • VOA: Variable Optical Attenuator
  • VOD: Video on Demand
  • VoIP: Voice over IP
  • VP: Virtual Path
  • VPLS: Virtual Private LAN Service
  • VPN: Virtual Private Network. Protected information transmission protocol utilizing tunneling, security controls, and endpoint address translation, with the aim of giving the end user the impression that a dedicated link exists between nodes
  • VPR: Virtual Path Ring
  • VPWS: Virtual Private Wire Service
  • VRF: Virtual Routing and Forwarding
  • VRRP: Virtual Routing Redundancy Protocol
  • VSI: Virtual Switch Interface or Virtual Switching Instance
  • VSR: Very Short Reach (protocol). Widely used protocol for SDH connection. Physical layer specification for a parallel fiber optic connection operating at up to 10 Gbps over very short distances of 300 m or less. Lowers the cost of a system, as lasers working over short distances are much cheaper.
  • VT-n: Virtual Tributary n

W

  • WADM: Wavelength Add/Drop Multiplexer
  • WAN: Wide Area Network. Physical or logical network enabling independent devices to communicate with each other over a common transmission interconnected topology in geographic areas larger than those served by local area networks.
  • Wander: Long-term time delay variations produced by long timescale phenomena, like temperature cycling effects in cables
  • Wavelength: Distance between crests of a wave. The wavelength determines the nature of the different forms of radiant energy comprising the electromagnetic spectrum.
  • WB: Wideband
  • WB-DXC: Wideband digital cross connect
  • WCDMA: Third generation wireless technology based on CDMA. See 3G.
  • WDM: Wavelength Division Multiplexing. Optical transmission technique sending two or more signals of different wavelengths simultaneously in the same direction over one strand of fiber, and then separating them by wavelength at the distant end. Each wavelength is a "virtual channel". See also DWDM and CWDM.
  • WEEE: Waste Electrical and Electronic equipment
  • WFQ: Weighted Fair Queuing
  • WLAN: Wireless LAN
  • WLL: Wireless Local Loop
  • Working channels: Channels over which normal traffic is transported when there are no switch events
  • WRED: Weighted Random Early Discard or Weighted Random Early Detection
  • WSDL: Web Services Description Language
  • WS-I: Web Services Interoperability
  • WSON: Wavelength Switched Optical Network
  • WSS: Wavelength Selective Switch
  • WTR: Wait To Restore
  • WTS: Wait To Switch

X

  • X.25: CCITT Packet Switching Protocol
  • XC: Cross Connect
  • XCS: Cross-Connect Set
  • XCU: Cross-Connect Unit
  • XFP: 10 gigabit small form-factor pluggable transceiver type
  • XIO: Cross-connect Input/Output card
  • XML: Extensible Markup Language


Y

  • YP: Y-Protection

Z

  • ZTI: Zero Touch Installation


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