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Communications and Networking Glossary

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Access Ethernet Private Line

|

Access Ethernet Private Line (EPL) service uses a point-to-point OVC to associate one OVC end point at a UNI and one OVC end point at an ENNI. One UNI can support only a single instance of the Access EPL service


Access Ethernet Virtual Private Line

|

Access Ethernet Virtual Private Line (EVPL) service uses a point-to-point OVC to associate one OVC end point at a UNI and one OVC end point at an ENNI. One UNI can support one or more Access EVPL instances


Access Provider

|

An operator MEN that offers the Ethernet access service type


Alarm Indication Signal (AIS)

|

A signal transmitted by an intermediate network element along a transport circuit to alert the receiving end of the circuit of a fault


All-to-One Bundling

|

A UNI attribute in which all CE-VLAN IDs are associated with a single EVC


Availability

|

A measure of the percentage of time that a service is useable

Bandwidth Profile

|

An Ethernet service characteristic that specifies the committed and excess bandwidth that may be consumed by a service at a reference point (e.g., a UNI)


Bandwidth Profile per CoS ID

|

A bandwidth profile applied on a per-class of service identifier basis


Bandwidth Profile per EVC

|

A bandwidth profile applied on a per-EVC basis


Best-Effort

|

A QoS class in which no specific traffic parameters and no delivery guarantees are provided

 

Carrier Ethernet 2.0

|

Carrier Ethernet is a ubiquitous, standardized, carrier-class service and network defined by five attributes that distinguish Carrier Ethernet from familiar LAN-based Ethernet. These are: Standardized services, scalability, reliability, quality of service and service management


CCM (Continuity Check Message)

|

CCM provides a means to detect connectivity failures in an MEG. CCM messages are transmitted periodically and do not require a response


CE

|

Customer Edge, Customer Equipment


CEN

|

Carrier Ethernet Network (used interchangeably with Metro Ethernet Network, MEN)


CESoETH

|

Circuit Emulation Services over Ethernet


CE-VLAN CoS (Customer Edge VLAN CoS)

|

The code point bits in the IEEE 802.1Q tag in a service frame that is either tagged or priority tagged


CE-VLAN CoS Preservation

|

An EVC attribute in which the CE-VLAN CoS of an egress service frame is identical in value to the CE-VLAN CoS of the corresponding ingress service frame


CE-VLAN ID/EVC Map

|

An association of CE-VLAN IDs with EVCs at a UNI


CE-VLAN ID Preservation

|

An EVC attribute in which the CE-VLAN ID of an egress service frame is identical in value to the CE-VLAN ID of the corresponding ingress service frame


CE-VLAN Tag (Customer Edge VLAN TAG)

|

The IEEE 802.1Q Customer VLAN Tag in a tagged service frame


CFM

|

Connectivity Fault Management. See IEEE 802.1ag


Circuit Emulation Service (CES)

|

A service that transports TDM-based traffic over a packet-based network


Class of Service (CoS)

|

A set of service frames that have a commitment from the service povider to receive a particular level of performance


Class of Service Identifier (CoS ID)

|

An indicator for a particular CoS instance. The mechanism and/or values of the parameters in the mechanism to be used to identify the CoS name that applies to the frame


CLE

|

Customer Located Equipment


Color-Aware

|

A bandwidth profile property where a predetermined level of bandwidth profile compliance for each service or ENNI frame, indicated by the color identifier, is taken into account when determining the level of compliance for each service or ENNI frame


Color-Blind

|

A bandwidth profile property where a predetermined level of bandwidth profile compliance for each E1 frame, if present, is ignored when determining the level of compliance for each E1 frame


Color ID (Color Identifier)

|

The mechanism and/or values of the parameters in the mechanism used to identify the color that applies to the frame at a given interface


Color Identifier for Service Frame

|

The mechanism and/or values of the parameters in the mechanism used to identify the color that applies to the frame at a given UNI. A particular color ID value may indicate color instance of green or yellow for a service frame. PCP and DSCP may indicate both CoS name and color. Information derivable from a) a set of one or more C-tag PCP values or b) a set of one or more DSCP values


Color Mode (CM)

|

CM is a bandwidth profile parameter. The Color Mode parameter indicates whether the color-aware or color-blind property is employed by the bandwidth profile. It takes a value of color-blind or color-aware only


Committed Burst Size (CBS)

|

CBS is a bandwidth profile parameter. It limits the maximum number of bytes available for a burst of service or ENNI frames sent at the E1 speed to remain CIR conformant


Committed Information Rate (CIR)

|

CIR is a bandwidth profile parameter. It defines the long-term average rate in bits per second of service or ENNI frames up to which the network delivers service or ENNI frames and meets the performance objectives defined by the CoS service attribute


Control House

|

A substation facility that contains control panels, batteries, battery chargers, supervisory control, power-line carrier, meters, and relays


Coupling Flag (CF)

|

A bandwidth profile parameter that allows choice between two modes of operation of the Bandwidth profile algorithm. It takes a value of 0 or 1 only


CPE (Customer Premises Equipment)

|

A network element located at and owned by the end customer


Cross Connect

|

A network device that demultiplexes, switches and remultiplexes signals. Low-order cross connects may switch individual voice channels or E1/T1 lines, while high-order cross connects may switch high speed optical signals


CSP

|

Communication Service Provider


C-Tag

|

Customer (Subscriber) VLAN Tag


C-Tag Frames

|

IEEE 802.1ad 1Q Ethernet Frames with one tag


Customer Edge (CE)

|

Equipment on the subscriber side of the UNI


Customer Edge VLAN CoS

|

The priority code point bits in the IEEE 802.1Q customer VLAN tag in a service frame that is either tagged or priority tagged


Customer Edge VLAN ID

|

The IEEE 802.1Q Customer VLAN tag in a tagged service frame. The identifier derivable from the content of a service frame that allows the service frame to be associated with an EVC at the UNI


C-VLAN (Customer VLAN)

|

A VLAN tag used by the end customer to distinguish internal services

 

DA

|

Destination Address


Data Service Frame

|

An Ethernet frame transmitted across the UNI toward the service provider or an Ethernet frame transmitted across the UNI toward the subscriber. A service frame can have unicast, multicast, or broadcast DA


DEI

|

Discard/Drop Eligibility Indicator


Differential Protection

|

A mechanism that disconnects faulty line segments when differential current measurements on both ends of the protection zone are higher than a set point


Digital Cross Connect

|

Digital cross-connects (DACs) (see Cross Connect) come large and small, handling only a few ports up to a couple of thousand. Narrowband, wideband and broadband cross-connects support channels down to DS0, DS1 and DS3 respectively


Distance Protection

|

A mechanism that trips breakers when impedance measurements vary from those taken under normal conditions


Distributed Grandmaster

|

A technology developed by RAD for bringing the PTP distribution functionality closer to base stations, obviating the need for full 1588 network upgrades and/or the deployment of GPS receivers in every cell site


Distribution Substation

|

An electric substation located near end-users. Distribution substation transformers change the subtransmission voltage to lower levels for use by end-users


Distribution Transformers

|

Reduce the voltage of the primary circuit to the voltage required by customers


DM

|

Delay Measurement


DMM

|

Delay Measurement Message


DMR

|

Delay Measurement Response


DNP3 (Distributed Network Protocol)

|

A set of communications protocols used between components in process automation systems. Its main use is in utilities such as electric and water companies


Double-Tagged Frames

|

IEEE 802.1ad Ethernet frames with two tags. The outer tag is an S-tag, the inner tag is a C-tag


Down-MEP

|

An MEP in an IEEE 802.1 compliant bridge that sends frames away from the bridge relay entity


DS0 (Digital Subscriber Level Zero)

|

A 64 kbps unit of transmission bandwidth. A worldwide standard speed for digitizing one voice conversation, and more recently, for data transmission. Twenty-four DS0s (24 x 64 kbps) equal one DS1


DS1 (Digital Signal Level 1) Channel

|

Framing specification used in transmitting digital signals at 2.048 Mbps on an E1 facility or 1.544 Mbps on a T1 facility


DSCP

|

Differentiated Services (Diff-Serv) Code Point


DSO (Distribution System Operator)

|

A utility handling the distribution of energy for a part of a country or a region generally on a medium voltage (MV) electric line below 220 kV. DSOs interconnect to TSOs and small power producers. A DSO can also be a power producer


Dual-Ended

|

A type of process where an MEP sends measurement information to a peer MEP that will perform the calculations


Dual Rate Bandwidth Profile

|

A bandwidth profile that specifies both CIR/CBS and EIR/EBS

 

E1

|

A 2.048 Mbps signal that supports thirty-two 64 kbps timeslots, at least 30 of which can transmit and receive data or digitized voice. The most common configurations for E1 lines are E1 PRI, and unchannelized E1


E-Access

|

Ethernet service types that use an OVC with at least one UNI OVC end point and one ENNI OVC end point


EFM (Ethernet in the First Mile)

|

A now disbanded task force that standardized 1) Ethernet DSL physical layers, 2) Ethernet inverse multiplexing (bonding), 3) new point-to-point Ethernet optical physical layers, 4) EPON, and 5) link layer OAM


Egress Frame

|

A frame sent from the service provider network to the CE


E-LAN

|

An MEF Ethernet service type distinguished by its use of a multipoint-to-multipoint EVC


Electrical Grid

|

An integrated system of electricity distribution, usually covering a large area


Electric Utility

|

An organization responsible for the installation, operation, or maintenance of an electric supply system


E-Line

|

An MEF Ethernet service type distinguished by its use of a point-to-point EVC


EMS

|

Element Management System


End Point Map

|

A mapping of specified S-tag VLAN ID values to specified OVC end point Identifiers


End Point Map Bundling

|

When multiple S-VLAN ID values map to a single OVC end point in the end point map, and the OVC associating that OVC end point is not a rooted-multipoint OVC


E-NNI/ENNI (External Network-to-Network Interface)

|

A reference point representing the boundary between two operator MENs that are operated as separate administrative domains


ENNI Frame

|

The first bit of the destination address to the last bit of the frame check sequence of the Ethernet frame transmitted across the ENNI


ENNI MTU

|

MTU of an ENNI frame at the ENNI


ENNI-N

|

ENNI network functional element


EPL

|

Ethernet Private Line


EP-LAN

|

Ethernet Private LAN


EP-Tree

|

Ethernet Private Tree


ETH-AIS

|

Ethernet Alarm Indication Signal


ETH-CC

|

Ethernet Continuity Check function


ETH-DM

|

Ethernet frame Delay Measurement function


Ethernet Access Provider

|

Operator of the MEN providing the OVC-based Ethernet service between a UNI and an ENNI


Ethernet Converter

|

Ethernet converters are low-cost and simple devices for connecting Ethernet over E1, T1, E3, T3, STM-1, OC-3 and STM-4, OC-12 access lines


Ethernet Demarcation

|

A key element in Carrier Ethernet transport and services, Ethernet demarcation provides a clear separation between the user and the network, allowing carriers to extend network visibility up to the user premises


Ethernet Extenders

|

Ethernet signal degradation typically limits Ethernet cable runs to 100 meters (328 feet). To achieve longer distances, an Ethernet extender is required. These devices can be used to drive Ethernet up to 5.5 kilometers over copper and more than 100 kilometers over fiber


Ethernet Frame

|

A data frame on a wire from preamble to FCS


Ethernet LAN Service

|

An Ethernet service type distinguished by its use of a multipoint-to-multipoint EVC


Ethernet Line Service

|

An Ethernet service type distinguished by its use of a point-to-point EVC


Ethernet Media Converter

|

Ethernet media converters are low-cost and simple devices for connecting Ethernet over E1, T1, E3, T3, STM-1, OC-3 and STM-4, OC-12 access lines


Ethernet modem

|

RAD Data Communications has a wide range of Ethernet modems with combined E1/T1 multiplexing capabilities for point-to-point Ethernet extension over any type of infrastructure or media


Ethernet over PDH (Plesiochronous Digital Hierarchy)

|

A method for carrying Ethernet traffic over PDH network lines such as E1/T1 or E3/T3. It is one of several technologies available to service providers who wish to offer new carrier-class Ethernet services over existing legacy infrastructure


Ethernet over SDH/SONET

|

Although SDH networks were originally engineered to transport voice traffic, many carriers are using their ubiquitous SDH/SONET infrastructure to deploy Ethernet services


Ethernet Virtual Connection (EVC)

|

An association of two or more UNIs that limit the exchange of frames to UNIs in the Ethernet Virtual Connection


EtherType

|

Ethernet Length/Type


ETH-LB

|

Ethernet Loopback function


ETH-LCK

|

Ethernet Lock signal function


ETH-LM

|

Ethernet Frame Loss Measurement function


ETH-LT

|

Ethernet Link Trace function


ETH-RDI

|

Ethernet Remote Defect Indication function


ETH-SLM

|

Ethernet Synthetic Loss Measurement function


ETH-Test

|

Ethernet Test function


E-Tree

|

An MEF Ethernet Tree (E-Tree) service type is any Ethernet service that is based on a rooted-multipoint Ethernet virtual connection (EVC)


EVC ID

|

The identifier for an EVC


EVC-MA

|

Ethernet Virtual Connection Maintenance Association


EVC Maximum Transmission Unit Size

|

The maximum size service frame allowed for an EVC


EVPL

|

Ethernet Virtual Private Line


EVP-LAN

|

Ethernet Virtual Private LAN


EVP-Tree

|

Ethernet Virtual Private Tree


Excess Burst Size (EBS)

|

A bandwidth profile parameter. It limits the maximum number of bytes available for a burst of frames sent at E1 speed to remain EIR-conformant


Excess Information Rate (EIR)

|

A bandwidth profile parameter. It defines the long-term average rate in bits per second of frames up to which the network may deliver frames but without any performance objectives

 

FCS

|

Frame Check Sequence


FD

|

Frame Delay


FDR (Frame Delay Range)

|

The difference between the observed percentile of delay at a target percentile and the observed minimum delay for the set of frames in time interval T


FDV

|

Frame Delay Variation


FDX

|

Full Duplex


Fiber Media Converter

|

A fiber media converter connects standard optical interfaces with electrical interfaces; links single mode fibers with multimode fiber cables; adapts dissimilar data rates; and converts different transmission protocols such as TDM E1/T1 and Ethernet


Fiber Optic Multiplexers

|

Fiber optic multiplexers are devices that combine multiple signals for transport on a common transmission path. RAD’s fiber optic multiplexers enable transmission of E1 or T1 channels, E3 or T3 tributaries and wire-speed Ethernet over a fiber optic link. A fiber optic multiplexer at the other end reverses the process


First Mile

|

Sometimes referred to as Local Loop, the final leg of delivering communications connectivity to a resident or customer. Typically seen as an expensive challenge because “fanning out” wires and cables is a considerably expensive and physically difficult task


FLR

|

Frame Loss Ratio


FM

|

Fault Management


Frame Delay

|

The time required to transmit a service or ENNI frame from ingress E1 to egress E1


Frame Delay Range

|

The difference between the observed percentile of delay at a target percentile and the observed minimum delay for the set of frames in time interval T


Frame Delay Variation

|

The difference in delay of two service frames

 

G.8031

|

An ITU standard defining Ethernet Linear Protection Switching


G.8032

|

An ITU standard defining Ethernet Ring Protection Switching


GARP

|

Generic Attribute Registration Protocol


GbE

|

Gigabit Ethernet


GFP (Generic Framing Procedure)

|

Defined by ITU-T G.7041. It allows efficient mapping of variable length, higher layer client signals, such as Ethernet, over a transport network like SDH/ SONET. Recently, GFP has been extended to lower speed PDH networks


GIWF (Generic Inter-Working Function)

|

Provides functionality that allows CE devices with a non-Ethernet I/F to send traffic over an Ethernet UNI


GRE (Generic Routing Encapsulation

|

A protocol that encapsulates other protocols in order to route them over IP networks


Grooming

|

The process of aggregating channels in order to transmit the aggregate over a physical link


G.SHDSL

|

G.SHDSL, or SHDSL, is a standardized method (ITU-T G.991.2) to transport symmetrical data rates on copper pair access lines. G.SHDSL offers bitrates from 192 kbps to 2.3 Mbps over a 2-wire single pair and up to 9.2 Mbps over four bonded pairs


G.SHDSL Modem

|

A G.SHDSL modem is a customer located transceiver, connecting users to a G.SHDSL service via the local DSLAM

 

HDX

|

Half Duplex


High Voltage Circuit Switching

|

An operation in which a circuit
breaker and disconnector de-energize a line (circuit breaker
action) and thereby redirect the electricity flow

 

IA

|

Implementation Agreement


IEC (The International Electrotechnical Commission)

|

An international non-profit, non-governmental standards organization that deals in power generation, transmission and distribution


IEC 60870-5-101 (IEC 101)

|

An IEC standard for telecontrol, Teleprotection, and associated telecommunications, using serial transmission


IEC 60870-5-104 (IEC 104)

|

An IEC standard for for telecontrol, Teleprotection, and associated telecommunications, using TCP/IP


IEC-61850

|

A IEC standard for electrical substation automation


IEEE

|

Institute of Electrical and Electronics Engineers


IEEE 1588

|

The IEEE precision time protocol (PTP) for frequency and Time Of Day distribution over packet switched networks


IEEE 802.1ag

|

IEEE standard for Ethernet connectivity fault management (CFM) OAM. 802.1ag may be used for testing liveliness of any Ethernet connection, whether a single link or end-to-end. See also Y.1731


IEEE 802.3ah

|

See EFM (Ethernet in the First Mile)


IEEE C37.94

|

A standard providing plug-and-play transparent communications between different manufacturers’ Teleprotection and multiplexer devices using multimode optical fiber. The standard defines clock recovery, jitter tolerances, physical connection method, and the equipment-failure actions for all communications link failures


IETF

|

Internet Engineering Task Force


IFDV

|

Inter-Frame Delay Variation


Ingress

|

The direction from the CE into the service provider network


Ingress Frame

|

A Frame sent from an E1 into the service provider network


Intelligent Electronic Device (IED)

|

Intelligent controllers of power system equipment, such as circuit breakers, transformers, and capacitor banks. IEDs receive data from sensors, and may issue commands (such as tripping circuit breakers) if they sense voltage, current, or frequency anomalies


IP (Internet Protocol)

|

IPv4 is for version 4 (RFC 791) and IPv6 is for version 6 (RFC 2460)


IPSec

|

Internet Protocol Security


ISDN (Integrated Services Digital Network)

|

A carrier-provided service that allows a variety of switched digital data and voice transmissions to be accommodated simultaneously. ISDN is available as BRI, PRI and B-ISDN


ITU-T

|

International Telecommunication Union – Telecommunication standardization sector


IWF

|

Inter-Working Function

 

L2

|

Layer 2


L2CP

|

Layer 2 Control Protocol


L2CP Tunneling

|

The process by which a frame containing a Layer 2 control protocol is transferred between external interfaces


LACP

|

Link Aggregation Control Protocol


LAG

|

Link Aggregation Group


LAN

|

Local Area Network


LB

|

Loopback. See Two-way OAM


LBM

|

Loopback Message


LBR

|

Loopback Reply


LCAS (Link Capacity Adjustment Scheme)

|

A method to dynamically increase or decrease the bandwidth of virtual concatenated containers in SDH. The LCAS protocol is specified in ITU-T G.7042. It allows on-demand increase or decrease of the bandwidth of the virtual concatenated group in a hitless manner. This brings bandwidth-on-demand capability for data clients like Ethernet when mapped into SDH containers


LCK (Lock)

|

An OAM message transmitted by a MEP to indicate intentional administrative or diagnostic actions


Link OAM

|

OAM confined to a single communications link (e.g., Ethernet link OAM per clause 57 of IEEE 802.3)


Link Protection Mechanism

|

Any mechanism (e.g., LAG) used to protect traffic in the event of link failure across multiple


LM

|

Loss Measurement


LMM

|

Loss Measurement Message


LMR

|

Loss Measurement Reply


LOF

|

Loss of Frame alignment


LTM

|

Link Trace Message


LTR

|

Link Trace Reply

 

M13 Multiplexer

|

An M13 multiplexer, or M13 mux, integrates 28 T1 tributary channels into a single T3 line using bit-level multiplexing and M13 framing format


MA

|

Maintenance Association


MAC

|

Media Access Control


Maintenance Association

|

IEEE 802.1ag defines Maintenance Association as a set of MEPs, each configured with the same MAID and MD level, established to verify the integrity of a single service instance. This term is equivalent to a maintenance entity group, or MEG, as defined by ITU-T Y.1731


Maintenance Domain

|

The network or the part of the network for which faults in connectivity can be managed


Maintenance Domain Intermediate Point

|

Maintenance Domain Intermediate Point or equivalently MEG Intermediate Point defined by ITU-T Y.1731. A SOAM entity consisting of two MHFs


Maintenance Entity

|

A point-to-point relationship between two MEPs within a single MA. This term is equivalent to a Maintenance Entity, or ME, as defined by ITU-T Y.1731


MD

|

Maintenance Domain


ME

|

Maintenance Entity


Mean Frame Delay

|

The arithmetic mean, or average of delays experienced by service or ENNI frames belonging to the same CoS frame set


Mean Time To Restore

|

The mean time from when a service is unavailable to the time it becomes available again


MEF

|

Metro Ethernet Forum


MEG

|

Maintenance Entity Group (equivalent to a MA)


MEN

|

A Metro Ethernet Network comprising a single administrative domain


MFD

|

Mean Frame Delay


MEP

|

Maintenance Association End Point


MIB

|

Management Information Base


Microwave

|

Radio waves with frequencies between 300 MHz and 300 GHz. Electric substations and cellular base stations commonly use microwave communications


MIP

|

Maintenance Domain Intermediate Point


Modbus

|

A serial communications protocol allowing for communication between many (approximately 240) devices connected to the same network


MTTR

|

Mean Time To Restore


MTU (Maximum Transfer Unit)

|

The size in bytes of the largest packet that can traverse a network or segment


Multicast Service Frame

|

A service frame that has a multicast destination MAC address


Multipoint-to-Multipoint EVC

|

An EVC with two or more UNIs

 

NERC (North American Electric Reliability Corporation)

|

A nonprofit corporation based in Atlanta, Georgia. Formed by the electric utility industry to promote the reliability and adequacy of bulk power transmission in the electric utility systems of North America


NERC-CIP

|

The NERC CIP (Critical Infrastructure Protection) plan is a set of requirements designed to secure the assets required for operating North America’s bulk electric system


NFV (Network Functions Virtualization)

|

An emerging networking technology in which functionality conventionally carried out in dedicated network elements is performed in software hosted on computer hardware or virtual machines


NID (Network Interface Device)

|

An element that forms the demarcation between two network domains. Typically a NID provides OAM and traffic condition functionalities


NMS

|

Network Management System


NNI

|

Network to Network Interface

 

OAM

|

Operations, Administration and Maintenance


On-Demand

|

OAM actions that are initiated via manual intervention for a limited time to carry out diagnostics. On-Demand OAM can result in singular or periodic OAM actions during the diagnostic time interval


One-Way OAM

|

An OAM exchange consisting of sending an OAM packet to a remote device for processing. One-way OAM may be used to measure packet loss and one-way delay (the latter when the two ends share a common clock)


Operator Virtual Connection

|

An association of OVC end points


OSS

|

Operations Support System


OVC

|

Operator Virtual Connection

 

P2P

|

Point-to-Point


PCP

|

Priority Code Point


Performance Monitoring

|

Performance Monitoring involves the collection of data concerning the performance of the network


PM

|

Performance Monitoring


PM Session

|

The application of a given PM function between a given pair of MEPs and using a given CoS frame set over some (possibly indefinite) period of time


Point-to-Point EVC

|

An EVC with exactly 2 UNIs


Power Line Carrier

|

A device for producing radio-frequency power for transmission on power lines


Power Transformer

|

A device for raising or lowering voltage as needed to serve the transmission or distribution circuits


Proactive OAM

|

OAM actions that are carried on continuously to permit timely reporting of fault and/or performance status


PTP (Precision Time Protocol)

|

See IEEE 1588


PW (Pseudowire)

|

A mechanism for tunneling a native service over an Ethernet, MPLA or IP network

 

QoS

|

Quality of Service


Qualified Set of Service Frames

|

The set of frames that comply with specific criteria, such as the arrival time at the ingress UNI and bandwidth profile compliance, on which a performance attribute is based

 

RDI

|

Remote Defect Indication


Relay (in power utilities)

|

A low-powered device used to activate a high-powered device. Relays are used to trigger circuit breakers and other switches in substations and transmission and distribution systems


Responder MEP

|

In a single-ended session, the Responder MEP receives SOAM PM PDUs, from the controller MEP, and transmits a response to the controller MEP


RFC-2544

|

An IETF benchmark methodology defining a specific set of tests to measure and report the performance characteristics of network devices. RFC 2544 contains, among other tests, a method for measuring throughput


RMP

|

Rooted Multipoint


Rooted-Multipoint EVC

|

A multipoint EVC in which each UNI is designated as either a root or a leaf. Ingress service frames at a root UNI can be delivered to one or more of any of the other UNIs in the EVC. Ingress service frames at a leaf UNI can only be delivered to one or more root UNIs in the EVC


RSTP

|

Rapid Spanning Tree Protocol


RTU (Remote Terminal Unit)

|

An industrial data collection device, typically located at a remote location, communicates data to a host system by using telemetry (such as radio, dial-up telephone, or leased lines)

 

Scheduled Downtime

|

A time interval agreed upon by both the subscriber and service provider during which a service may be disabled by the service provider


SDH (Synchronous Digital Hierarchy)

|

The European standard for using optical media as the physical transport for high speed, long haul networks


SDN (Software Defined Networking)

|

An emerging networking technology in which conventional control plane protocols are replaced by centralized software applications that configure simple SDN switches in the network


Service Assured Access

|

A collection of networking attributes throughout the service lifecycle designed to increase revenues and reduce total cost of ownership for service providers


Service Assured Networking

|

A collection of networking attributes throughout the service lifecycle designed to offer better service performance and reduced total cost of ownership for power utilities communications


Service Frame

|

An Ethernet frame transmitted across the UNI toward the MEN or an Ethernet frame transmitted across the UNI toward the subscriber


Service Level Agreement

|

The contract between the subscriber or operator and service provider specifying the agreed to service level commitments and related business agreements


Service Level Specification

|

The technical specification of the service level being offered by either the service provider to the subscriber in the case of an EVC service or by an operator to a service provider in the case of an OVC


Service Multiplexing

|

A UNI service attribute in which the UNI can support more than one EVC instance


Service OAM

|

Service OAM is OAM used to monitor an individual service


Service Provider

|

The organization responsible for the UNI to UNI Ethernet service(s)


SHDSL (Single-Pair High-Speed Digital Subscriber Line)

|

A DSL transmission standardized in ITU-T G.991.2. The original SHDSL technology could transport data symmetrically at rates of 192 kbps to 2.3 Mbps over 2-wire, or 384 kbps to 4.6 Mbps over 4-wire. The latest version (ex SHDSL.bis) uses more advanced line coding and multi-pair bonding technology to reach transmission rates up to 5.69 Mbps on one pair (2-wire) or a rate up to 22.8 Mbps over 8-wire


Short Haul Modem

|

A modem designed for use in transmitting over relatively short distances across unloaded metallic circuits. Also called a line driver or limited distance modem (LDM)


Single-Ended (in OAM)

|

A type of process where an MEP sends a measurement request and the peer MEP replies with the requested information so the originating MEP can calculate the measurement


Single Rate Service

|

A service that specifies either a CIR/CBS or EIR/EBS


SLA

|

Service Level Agreement


SLM

|

Synthetic Loss Measurement: See Y.1731


Smart Grid

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Bi-directional electric grids and communication networks that improve the reliability, security, and efficiency of the electric system for small-to-large-scale generation, transmission, distribution, storage, and consumption


SNMP

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Simple Network Management Protocol


SNMP Agent

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An SNMP entity containing one or more command responder and/or notification originator applications (along with their associated SNMP engine). Typically implemented in a network element


SNMP Manager

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An SNMP entity containing one or more command generator and/or notification receiver applications (along with their associated SNMP engine). Typically implemented in an EMS or NMS


SOAM

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Service Operations, Administration, and Maintenance


SOAM PDU

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Service OAM frame, or Protocol Data Unit. Specifically, those PDUs defined in IEEE 802.1ag, ITU-T Y.1731 and related MEF specifications


SONET (Synchronous Optical Network)

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A North American standard for using optical media as the physical transport for high speed long-haul networks. SONET basic speeds start at 51.84 Mbps and go up to 2.5 Gbps


SP

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Service Provider


S-Tag

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Service (Provider) Tagged Frame


S-Tag Frames

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IEEE 802.1ad Ethernet frames with one tag: S-Tag. The values of the S-VLAN IDs are in the range between 1 and 4094


Step-Down Transmission Substation

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Located at switching points in an electrical grid. They connect different parts of a grid and are a source for sub-transmission lines


Step-Up Transmission Substation

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Receives electric power from a nearby generating facility and uses a large power transformer to increase the voltage for transmission to distant locations


STP (Spanning Tree Protocol)

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An Ethernet protocol for loop avoidance


Substation Automation Systems

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All equipment that can be found in a substation control room, such as protection relays to protect the lines against fault or RTUs (remote terminal units) allowing substation measures to be sent to SCADA


Substations

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A high-voltage electric system facility. It is used to switch generators, equipment, and circuits or lines in and out of a system


Supervisory Control

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Equipment that allows for remote control of a substation’s functions from a system control center or other point of control


Supervisory Control and Data Acquisition (SCADA)

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A common industrial process control application that collects data from sensors on the shop floor or in remote locations and sends it to a control center


S-VLAN (Service VLAN)

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Also referred to as provider VLAN, a VLAN is used by the service provider to distinguish customers


S-VLAN ID

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The 12 bit VID field in the S-tag of an ENNI frame


Sync-E (Synchronous Ethernet)

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A mechanism defined in ITU-T standards G.8261, G.8262 and G.8264 to distribute highly accurate frequency over the Ethernet physical layer, using clock mechanisms similar to those used in SDH/SONET. As Sync-E operates on a single physical link, end-to-end frequency distribution requires all nodes along the entire clock distribution path to support Sync-E


Synchrophasor

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A device for precise real-time measurement of voltages and/or currents at points in an electric grid. The information is obtained from monitors called PMUs (phasor measurement units)


Synthetic Frame

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An Ethernet OAM frame fashioned to share fate with service traffic


Synthetic Traffic

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Traffic consisting of synthetic frames. Delay measurements typically use Synthetic Traffic to overcome the lack of standardized time-carrying fields in user traffic. Other OAM functions, such as frame loss, may also use synthetic frames

 

T1

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A digital transmission with a capacity of 1.544 Mbps used in North America. A T1 may be channelized into 24 DS0s, each capable of carrying a single voice conversation or data stream. T1 may be carried on coaxial cable or two twisted pairs


Tag

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An optional field in a frame header


Teleprotection

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Any of several protection schemes used in high-voltage transmission systems in order to enable the isolation of faults from the rest of the grid. Teleprotection systems consist of protection relays located remotely from each other, and a communications link between them


Timing over Packet Standards

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Various methods and standards developed to ensure that accurate time and frequency is distributed in packet-based networks


TLV

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Type, Length, Value


TOD

|

Time Of Day


Traffic Conditioning

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A process responsible for classification, filtering, metering, marking, policing, shaping and, in general, conditioning the subscriber flow to ensure it is conformant before forwarding the traffic into or out of the network


Traffic Duplication

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A unique technology developed by RAD to allow networks with mission critical applications to enhance reliability and performance. It can be used to minimize delay on critical utility applications (such as Teleprotection) by capitalizing on Carrier Ethernet’s reduced latency at higher speeds


TSO (Transmission System Operator)

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A utility handling the transport of energy for a country generally on electrical high voltage (HV) line above 220 kV (kiloVolts). A TSO is also responsible for the exchange of energy between countries


Two-Way OAM

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An OAM exchange consisting of sending an OAM packet to a remote device, which reflects it back to the originator. Two-way OAM may be used to measure round-trip delay

 

UNI (User Network Interface)

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The physical demarcation point between the responsibility of the service provider and the responsibility of the subscriber


UNI-C

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A compound functional element used to represent all of the functional elements required to connect an MEN subscriber to an MEN implementing a UNI-N


Unicast Service Frame

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A service frame that has a unicast destination MAC address


UNI-MEG

|

UNI Maintenance Entity Group


UNI-N

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A compound functional element used to represent all of the functional elements required to connect an MEN to an MEN subscriber implementing a UNI-C


Unscheduled Downtime

|

A time interval not agreed upon by both the subscriber and service provider during which the service provider determines that the service is not useable


UpMEP

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An MEP in an IEEE 802.1 bridge that sends frames toward the bridge relay entity


User Network Interface

|

The physical demarcation point between the responsibility of the service provider and the responsibility of the subscriber

 

VCAT (Virtual Concatenation)

|

An inverse multiplexing technique used to split SDH/SONET clients into logical channels, which may be transported independently


VID

|

VLAN Identifier


Virtual NID (vNID)

|

A “virtual NID” functionality is provided by the access provider (AP) to the E-access service purchased by the service provider (SP). vNID functionality allows the SP to monitor selected objects associated with the UNI in the AP’s network, and allows the SP to set values for selected objects


Virtual UNI (VUNI)

|

The component consisting of a collection of service attributes in the VUNI provider’s MEN


VLAN

|

Virtual LAN


VLAN ID

|

VLAN Identifier


 

WAN

|

Wide Area Network


WTR

|

Wait to Restore

 

xDSL modems

|

xDSL modems use digital subscriber line (DSL) technology to transmit high-bandwidth information over existing copper phone lines to homes and businesses. xDSL modems support various data rates and ranges, depending on the type of DSL technology they incorporate. Common xDSL services include asymmetric DSL (ADSL, ADSL2, ADSL2+), symmetric DSL (SDSL), high-bitrate DSL (HDSL), symmetric high-bitrate DSL (SHDSL, SHDSL.bis) and very high bit-rate DSL (VDSL, VDSL2)


xSTP

|

Spanning Tree Protocol (multiple variations)

 

Y.1564

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An ITU recommendation specifying Ethernet service activation testing. Y.1564 may be used to assess the proper configuration of an Ethernet network before committing to deliver Ethernet-based services


Y.1731

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ITU-T standard Y.1731 is an Ethernet OAM (operations, administration and maintenance) standard for testing an Ethernet service and for monitoring its performance