Telecom Glossary
AcronymDescriptionApplicationGroupRead more
ACRAdaptive Clock RecoveryA method for TDM pseudowires that ensures the TDM signals are clocked at the same rate at the near- and the far-end of a TDM over Packet connection. The adaptive method does not require support of Synchonous Ethernet or PTP protocols. See also DCRtdmopTDM over Packet Solutions
ADMAdd-Drop MultiplexerA type of SONET/SDH network element providing transport of Ethernet, IP, MPLS, and TDM servicesEquipment
AISAlarm Indication SignalIndication that a fault is detected in the originating or upstream equipmentAlarm
APSAutomatic Protection SwitchingUsing 2 fiber pairs between SONET/SDH nodes to increase the availibility of the connection, through protection against fiber, node or operator failuresProtocol
B1, B2, B3BIP level 1, 2, 3A SONET/SDH overhead byte for link monitoring based on parity generation and check. Also B2 and B3 are defined, monitoring at sub-channel levels.Overheadbyte
BERTBit Error Rate TestA method to test network connections. A generator creates a specific test pattern, e.g. PRBS, which is sent across a TDM network path. At the far end, or along the path, a monitor verifies whether the received stream matches the pattern, and reports any received bit errors.Test
BITSBuilding Integrated Timing SystemEquipment that generates and distributes high-quality synchronization signals inside a telecom building, often based on high stability oscillators and using GPS as a reference signalsynchronizationSynchronization
BLSRBidirectional Line Switched RingUsing 2 fiber pairs between all SONET nodes in a ring topology to increase the availibility of connections, through protection against fiber, ring network, node or operator failures. SONET terminology for MS SPRING.Protocol
CEMCircuit EMulationGeneric term for Circuit Emulation Service, related terminology are TDM over Packet and Pseudo WiretdmopTDM over Packet Solutions
CEP(SONET/SDH) Circuit Emulation over PacketA method to transport SONET SPEs or SDH Virtual Triburaries over a packet network using pseudowire concepts (IETF RFC 4842)tdmopTDM over Packet Solutions
CESCircuit Emulation ServiceA method to transport a TDM circuit (e.g. E1, T1, SONET, SDH, CPRI) over a packet network. This is a special case of pseudowire transporttdmopTDM over Packet Solutions
CESoPSNCircuit Emulation Service over Packet Switched NetworkA method to transport PDH TDM services structure aware over a packet network using pseudowire concepts (IETF RFC 5086)tdmopTDM over Packet Solutions
CPoP SFPChannelized PDH over PacketA Smart SFP with DS3 line interface, with a M13 multiplexer supporting packet transport for up to 28 DS1 channels via SAToPsmartsfpSmart SFP
CPRICommon Public Radio InterfaceA standarized method to transport mobile network radio data across a electrical or optical linkProtocol
CSoP SFPChannelized SONET/SDH over PacketA Smart SFP with OC3/STM1 line interface, with an embedded multiplexer supporting packet transport for up to 84 DS1 or 63 E1 channels via SAToPsmartsfpSmart SFP
CVCode ViolationIndication that a CRC or parity error is present in received dataAlarm
DACSDigital Access and Cross-connect SystemA type of network element providing cross connections of 100s or 1000s of SONET/SDH, PDH or TDM servicesEquipment
DCCData Communications ChannelA low speed in-band channel for engineering or operations support between SONET/SDH or OTN network elements, also know as ECC or GCCchannelSmart SFP
DCRDifferential Clock RecoveryA method for TDM pseudowires that ensures the TDM signals are clocked at the same rate at the near- and the far-end of a TDM over Packet connection. The differential method relies on a network wide reference clock using Synchonous Ethernet or PTP protocol. See also ACR.tdmopTDM over Packet Solutions
DCSDigital Cross-connect SystemA type of network element providing cross connections of 100s or 1000s of SONET/SDH, PDH or TDM servicesEquipment
DS0Digital Signal Level 064 Kb/s data/voice channelChannel
DS1Digital Signal Level 1A TDM signal operating at 1 544 kb/s. The signal can be transported over a T1 line, or multiplexed via DS3, SONET or SDHChannel
DS3Digital Signal Level 3A TDM signal operating at 44 736 kb/s. The signal can be transported over a T3 line, or multiplexed via SONET or SDHchannelSmart SFP
E1E signal level 1A TDM signal operating at 2 048 kb/s. The signal can be multiplexed via SONET or SDHChannel
E3E signal level 3A TDM signal operating at 34 368 kb/s. The signal can be multiplexed via SONET or SDHchannelTDM over Packet Solutions
ECCEmbedded Communications ChannelA low speed in-band channel for engineering or operations support between SONET/SDH or OTN network elements, also know as DCC or GCCChannel
ECIDEthernet Circuit IDentifierA header field that uniquely identifies a TDM pseudowire channel on an Ethernet network (MEF-8)tdmopTDM over Packet Solutions
Smart SFP
EECEthernet Equipment ClockThe clock function inside Ethernet equipment that generates and distributes high-quality synchronization signals on the Ethernet networksynchronizationSynchronization
EMSElement Management SystemA management system that typically supports a single or few equipment nodesManagement
EOCEmbedded Operations ChannelA low speed in-band channel for engineering or operations support between SONET/SDH or OTN network elementsChannel
EOSEthernet over SONET/SDHEthernet packet transport via GFP over SONET/SDH networkprotocolEoS Smart SFP
EoS SFPEthernet over SONET/SDHA Smart SFP supporting point to point Ethernet transport across a SONET/SDH network via the optical OC48/STM16 interfaceSmart SFPSmart SFP
EOWEngineering Order WireA low speed in-band channel for engineering or operations support between SONET/SDH or OTN network elementsChannel
EPARExplicit Pointer Adjustment RequestA method to transparently forward pointer adjustments from SONET/SDH layer across a CEP pseudowire. Related methods are ACR and DCR.tdmopTDM over Packet Solutions
Smart SFP
ETHEthernetA networking technology based on packet forwarding, using the Destination MAC address to determine the next destinationNetwork
GCCGeneral Communications ChannelA low speed in-band channel for engineering or operations support between OTN network elementsChannel
GFPGeneric Framing ProcedureA generic method to encapsulate client service signals such as Ethernet, IP or MPLS packets for transport over SONET/SDH or OTN networksprotocolEoS Smart SFP
HDLCHigh-level Data Link ControlA bit-oriented transparent synchronous data link layer protocol (ISO/IEC 13239:2002)Protocol
IPInternet ProtocolA networking technology based on packet forwarding, using the IP address to determine the next destinationNetwork
IWFInterworking FunctionThe function that converts serial TDM data into packets and vice versa, in TDMoP equipmentequipmentTDM over Packet Solutions
Smart SFP
J0, J1, J2J byte overheadA SONET/SDH overhead byte used for link or path identification purposes. Overheadbyte
K1, K2K byte overheadA pair of SONET/SDH overhead bytes used for link status reporting and transfer of protection protocol information between SONET/SDH nodes. See also APS.Overheadbyte
LAPDLink Access Procedure-D ChannelA data link layer protocol used for OAMP transport across SONET/SDH or OTN networksProtocol
LBOLine Build OutA function in a LIU device to prevent cross-talk on short electrical TDM links using a configurable level of output signal attenuationEquipment
LCASLink Capacity Adjustment SchemeA method to automatically adjust the bandwidth of a VCG based on availability of end-to-end Virtual ConnectionsProtocol
LIULine Interface UnitThe physical layer interface chip, supporting TDM signals such as E1, T1 or T3equipmentTransparent Network Migration
LOCLoss of ClockIndication that the Clock signal of the received signal is lost or not usableAlarm
LOFLoss of FrameIndication that the frame structure of the received signal is lostAlarm
LOPLoss of PointerIndication that the Pointer value can not be detected in the received signal, in SONET/SDH equipmentAlarm
LOPSLoss of Packet SynchronizationIndication that some or all received packets are lost, in TDMoP equipmentAlarm
LOSLoss of SignalAn alarm that indicates no signal is receivedAlarm
LPLLocal Packet LostIndication that a single packet is lost, due to missing sequence number, in TDMoP equipmentAlarm
M13MUX DS1 DS3A function to aggregate multiple DS1 signals for transport over a DS3 linkequipmentChannelized Network Migration
MEFMetro Ethernet ForumAn organization defining standards for Ethernet networks and services.Organization
MLPPPMulti-Link Point-to-Point ProtocolA method to increase network bandwidth using a bundle of PPP linksProtocol
MPLSMulti Protocol Label SwitchingA networking technology based on packet forwarding, using a label to dermine the next destinationProtocol
MSPMultiplex Section ProtectionUsing 2 fiber pairs between SONET/SDH nodes to increase the availibility of the connection, through protection against fiber, node or operator failuresProtection
MSPPMultiservice Provisioning PlatformA type of SONET/SDH network element providing transport of Ethernet, IP, MPLS, and TDM servicesEquipment
MS SPRINGMultiplex Section Shared Protection RingUsing 2 fiber pairs between all SONET/SDH nodes in a ring topology to increase the availibility of connections, through protection against fiber, ring network, node or operator failures. SONET terminology for BLSR.Protection
MTIEMaximum Time Interval ErrorA method to measure the quality of a TDM signal using the maximum time error with respect to a stable reference over a given time intervalsynchronizationSynchronization
MUXMultiplexerA network element in a PDH, SONET/SDH or OTN network that aggregates TDM signals for transportequipmentChannelized Network Migration
NIMNon-Intrusive MonitorA function on PDH or SONET/SDH equipment to monitor quality or status of TDM traffic while it passes through the equipment. It is non-intrusive in the sense that it does not change the content of the signal, it only reports observed bit-errors as failures or as a performance countEquipment
NMSNetwork Management System A management system that supports a network level view of large set of equipment nodesManagement
NTPNetwork Time ProtocolA method to distribute time across an IP packet network (IETF RFC 5905)synchronizationSynchronization
NUTNon-preemptive Unprotected TrafficA specific use-case defined in the BLSR or MS SPRING protection protocol, allowing higher usage of available path resources on a TDM ring network.Protection
OAMOperations, Administration and MaintenanceA set of management functons supported on a network interface or equipment nodesManagement
OAMPOperations, Administration, Maintenance and ProvisioningA set of management functons supported on a network interface or equipment nodesManagement
OC-3Optical Carrier level 3A SONET fiber connection operating at 155.52 Mb/schannelSmart SFP
OC-nOptical Carrier-numberA SONET fiber connection operating at n * 51.84 Mb/s. OC-1, OC-3, OC-12, OC-48, OC-192 and OC-768 are defined.channelSmart SFP
OSPFOpen Shortest Path FirstA routing protocol for packet networks using a shortest path algorithm to determine optimal routesProtocol
OTNOptical Transport Network A networking technology using pre-allocated fixed capacity paths for end-to-end traffic connectionsNetwork
OTUOptical Transport UnitA channel supported in OTN network hierarchyChannel
OWOrder WireA low speed in-band channel for operations support between SONET/SDH or OTN network elementsChannel
PDHPleisiochronous Digital HierarchyA networking technology using pre-allocated fixed capacity paths for end-to-end traffic connections; a multiplexing structure with near synchronous timing is used to combine multiple paths on a single linkNetwork
PJPointer JustificationIndication that a positive or negative pointer adjustment was detected in the received signal, in SONET/SDH equipmentAlarm
PLEPrivate Line Emulation over PacketA method for encapsulating high-speed serial signals over packet switched networks. This emulation suits applications where complete signal transparency is required (IETF draft schmutzer bess ple)tdmopTDM over Packet Solutions
PLMPayload Label MismatchIndication that the payload received in the relevant channel does not match with the expected payload type, in SONET/SDH equipmentAlarm
POHPath OverheadAn overhead channel at the path layer in SONET/SDHchannelSmart SFP
POSPPP over SONET/SDHA method for transporting multi-protocol datagrams over point-to-point links (IETF RFC 2615)Protocol
PPPPoint-to-Point ProtocolA method for transporting IP, Ethernet or other services over point-to-point links (IETF RFC 1661)Protocol
PPSPulse per SecondInterface that generates and receives high-quality clock signal at 1 Hz (ITU-T G.703 section 19)synchronizationSynchronization
PRBSPseudo Random Bit SequenceA TDM signal to test network connections. A generator creates a specific test pattern which is sent across a TDM network path. At the termination point, or along the path, a monitor verifies whether the receive stream matches the pattern, and reports any received bit errors. See also BERT.Test
PRCPrimary Reference ClockHigh accuracy and high stability reference clocksynchronizationSynchronization
PSNPacket Switch NetworkA networking technology based on packet forwardingNetwork
PTPacket TerminationGeneric protocol terminology, often related to IP packet transport on TDM networks. See also EOS, GFP, LAPD, POS and PPP.protocolEoS Smart SFP
PTPPrecision Time ProtocolA method to distribute highly accurate time across a packet network (IEEE 1588)synchronizationSynchronization
PWPseudo WireA method to transport various services such as Ethernet, TDM, PDH, and SONET/SDH over packet switched networks (PSNs) using IP or MPLS (IETF RFC 3985)tdmopTDM over Packet Solutions
Smart SFP
RAIRemote Alarm IndicationIndication that the far-end equipment has detected a network or equipment alarmAlarm
RDIRemote Defect IndicationIndication that the far-end equipment has detected a network or equipment defectAlarm
RoERadio over EthernetA method to transport CPRI radio signals over a packet network using pseudowire concepts (IEEE 1914.3)tdmopTDM over Packet Solutions
Smart SFP
RTPReal-time Transport ProtocolA method to provide end-to-end network transport functions suitable for applications transmitting real-time data, such as audio, video or TDM, over a packet network (IETF RFC 3550)tdmopTDM over Packet Solutions
Smart SFP
SASEStand Alone Synchronization EquipmentEquipment that generates and distributes high-quality synchronization signals inside a telecom building, often based on high stability oscillators and using GPS as a reference signalsynchronizationSynchronization
SAToPStructure-Agnostic TDM over Packet A method to transport PDH TDM services in structure-agnostic, transparent mode over a packet network using pseudowire concepts (IETF RC 4553)tdmopTDM over Packet Solutions
Smart SFP
SDHSynchronous Digital HierarchyA networking technology using pre-allocated fixed capacity paths for end-to-end traffic connections; a multiplexing structure with synchronous timing is used to combine multiple paths on a single linkNetwork
SECSynchronous Equipment ClockThe clock function inside SONET/SDH equipment that generates and distributes high-quality synchronization signals on the SONET/SDH networksynchronizationSynchronization
SEFSeverely Errored FramingIndication that 2 or more framing errors were detected in received signal during a time windowAlarm
SESSeverely Errored SecondIndication that during a 1 second interval a high amount of frame errors were detected in received signalAlarm
SFPSmall Form-factor PluggableA pluggable module for optical or electrical network connections to equipment, with a standardized mechanical form factor and standardized electrical interfaces for data and managementEquipment
SNCSubnetwork ConnectionIn SDH networks, a connection based on VC-n pathsProtocol
SNCPSubnetwork Connection ProtectionIn SDH networks, a 1+1 protected connection based on VC-n pathsProtocol
SOHSection OverheadAn overhead channel at the section layer in SONET/SDHchannelSmart SFP
SONETSynchronous Optical NETworkA networking technology using pre-allocated fixed capacity paths for end-to-end traffic connections; a multiplexing structure with synchronous timing is used to combine multiple paths on a single linkNetwork
SPESynchronous Payload EnvelopeThe payload area of the STSs or VCs of a SONET connection, typically used for transport of client signals such as Ethernet, IP, MPLS, TDM or PDHchannelChannelized Network Migration
SRTSSynchronous Residual Time StampA mehod for CES equipment to ensure that the TDM signals are clocked at the same rate at the near- and the far-end of a TDM over Packet connection. The residual timestamp method relies on a common reference clock available at the near- and far-end equipment nodes (ITU-T I.363.1)tdmopTDM over Packet Solutions
Smart SFP
SSFServer Signal FailureIndication that a generic failure is present in a higher layer structure of the received signalAlarm
SSMSynchronization Status MessageA method to transfer the quality level and status of the local equipment clock to other equipment nodes via messages on a TDM or Packet network linksynchronizationSynchronization
SSUSynchronization Supply UnitEquipment that generates and distributes high-quality synchronization signals inside a telecom building, often based on high stability oscillators and using GPS as a reference signalsynchronizationSynchronization
ST3Stratum 3A network reference clock with quality and stability according Stratum level 3, also defined are ST1, ST2, ST3E, and ST4synchronizationSynchronization
STM-1Synchronous Transfer Mode level 1An SDH fiber connection operating at 155.52 Mb/schannelTransparent Network Migration
STM-nSynchronous Transfer Mode level nAn SDH fiber connection operating at n * 155.52 Mb/s. STM-0, STM-1, STM-4, STM-16, STM-64 and STM-192 are defined.channelTransparent Network Migration
STS-3Synchronous Transport Signal level 3The payload area of a SONET connection, providing a transport capacity of about 50 Mb/schannelChannelized Network Migration
STS-nSynchronous Transport Signal level nThe payload area of a SONET connection, providing a transport capacity of about n * 50 Mb/schannelChannelized Network Migration
STS-ncContiguous Concatenation of N STS-1 SPEsThe payload area of the SONET connection, bundled as a set of consecutively ordered SPEschannelEthernet over SONET SDH
SYNCSynchronizationA generic concept to enable multiple equipment node in a network to operated in time synchronous mode. See also NTP, PTP, SyncEsynchronizationSynchronization
SyncESynchronous EthernetA method to distribute highly accurate frequency reference across a packet network using the Ethernet physical layer (ITU-T G.8261)synchronizationSynchronization
T1T carrier signal at the DS-1 rateA TDM transport link operating at 1 544 kb/s.channelTransparent Network Migration
T3T carrier signal at the DS-3 rateA TDM transport link operating at 44 736 kb/s.channelChannelized Network Migration
TDEVTime DeviationA method to characterize the quality and performance of a TDM signal using statistical analysis of the phase stability of the signal over a given time intervalsynchronizationSynchronization
TDMTime Division MultiplexingA generic method the multiplex serial signals where each signal is allocated a time-slot. See also OTN, PDH, SDH, SONETNetwork
TDMoPTDM over PacketA method to transport TDM signals across a packet network. Also known as tdmop and CEM.tdmopTDM over Packet Solutions
Smart SFP
TPoP SFPTransparent PDH over PacketA Smart SFP with E1 or T1/DS1 electrical interface, supporting single channel transparent packet transport via SAToP protocolSmart SFPSmart SFP
TIMTrace Identifier MismatchIndication that the received trail trace identifier (J0, J1, J2) does not match with the expected identifier, in SONET/SDH equipmentAlarm
TSoPTransparent SONET/SDH over PacketA method to transport SONET/SDH signals in transparent mode over a packet network using pseudowire concepts similar to SAToP (IETF draft manhoudt pwe3 tsop)tdmopTDM over Packet Solutions
Smart SFP
TSoP SFPTransparent SONET/SDH over PacketA Smart SFP with OC3/STM1, or OC12/STM4 or OC48/STM16 optical interface, supporting single channel transparent packet transport via TSoP protocolSmart SFPSmart SFP
TUTributary UnitThe payload area of an SDH lower order signal, including structure information.channelChannelized Network Migration
TUG-nTributary Unit Group, level nA bundle of TUs combined in a GroupchannelChannelized Network Migration
TU-nTributary Unit, level nThe payload area of an SDH lower order signal, including structure information. TU1, TU2, TU 12, and TU3 are defined.channelChannelized Network Migration
UASUnavailable SecondsIndication reporting the amount of seconds the service was unavailableAlarm
UPSRUnidirectional Path Switched RingUsing 2 diversely switched paths on a SONET ring topology to increase the availibility of connections, through protection against fiber, ring network, node or operator failures. Protocol
VCVirtual ContainerThe payload area of an SDH connection, typically used for transport of client signals such as Ethernet, IP, MPLS, TDM or PDHchannelChannelized Network Migration
VC-nVirtual Container Level nVC-11, VC-12, VC-2, VC-3, and VC-4 are definedchannelChannelized Network Migration
VC-n-xcContiguous Concatenation of X Virtual Containers at Level nThe payload area of an SDH connection, bundled as a set of consecutively ordered VCsChannel
VCATVirtual ConcATenationThe capacity of the SONET/SDH payload area is increased by bundling a set of SPEs or VCsChannel
VCGVirtual Concatenation GroupA group or bundle of VCs or SPEs using VCATChannel
VCoP SFPVirtual Container over Packet Smart SFPA Smart SFP with DS3 or OC3/12 line interface, with embedded multiplexer supporting packet transport for up to 12 STS1 SPE1 channels via CEP protocolSmart SFPSmart SFP
VTVirtual TributaryThe payload area of a SONET connection, typically used for transport of client signals such as Ethernet, IP, MPLS, TDM or PDHchannelChannelized Network Migration
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