Protocol standard used for the transport of time-dependent Constant Bit Rate (CBR) traffic (e.g. audio and video) and the emulation of TDM-based circuits (i.e. DS1, E1). Timing information is required to be exchanged between the source and the destination. AAL1 supports QoS Class A.
AAL2 - AAL type 2
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Protocol standard for supporting time-dependent slow or Variable Bit Rate (VBR-RT) connection-oriented traffic (e.g. packetized and compressed audio and video). Timing information is required to be exchanged between the source and the destination. AAL2 supports QoS Class B.
AAL 3/4 - AAL type 3 and 4
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Protocol standard for supporting both connectionless and connection-oriented Variable Bit Rate (VBR-NRT) traffic. AAL3 supports QoS class C while AAL4 supports QoS class D. They are currently combined into one type. AAL3/4 also performs resequencing and cell identification operations. AAL3/4 services are suitable for supporting interworking with Frame Relay, SMDS and X.25.
AAL5 - AAL type 5
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Protocol standard for supporting connection-oriented Variable Bit Rate (VBR-NRT) data traffic and signaling messages. AAL5 supports QoS Class X. AAL5 services are suitable for supporting interworking with most data networking protocols, such as Frame Relay, SMDS, Ethernet and IP.
AAL (ATM Adaptation Layer)
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A collection of standardized protocols that adapt user traffic to the cell format. The AAL is subdivided into the Convergence Sublayer (CS) and the Segmentation and Reassembly (SAR) sublayer. There are several types of AALs (AAL1, AAL2, AAL3/4 and AAL5) to support the various AAL service classes.
A-bis
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This is a GSM term for an interface linking between the BTS (base transceiver station) and the BSC (base station controller). Other GSM interfaces are the A between the BSC and the MSC (mobile switching controller), and the E between the MSC and the PSTN.
ABR (Available Bit Rate)
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One of five ATM Forum-defined service categories. In this service type, the network makes the best effort to pass the maximum number of cells but does not guarantee cell delivery. Supports variable bit rate data traffic with flow control, a minimum guaranteed data transmission rate and specified performance parameters. In exchange for regulating user traffic flow, the network offers minimal cell loss of accepted traffic. Traffic parameters are PCR and MCR. QoS parameters are CLR and CER.
Address
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A coded representation of the origin or destination of data.
An ITU standard technique for encoding analog voice signals into a digital form at 32 kbps (half the standard PCM rate).
Agent
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In SNMP, this refers to the managed system.
AIM (ATM Inverse Multiplexing)
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See IMA.
AIS (Alarm Indication Signal)
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One of the OAM function types used for fault management (see also CC, RDI).
Asynchronous Transmission
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A transmission method that sends units of data one character at a time. Characters are preceded by start bits and followed by stop bits, which provide synchronization at the receive terminal. Also called start-stop transmission.
ATM (Asynchronous Transfer Mode)
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A standard (ITU) implementation of cell relay, which is a packet switching technique using packets (cells) of a fixed length. It is asynchronous in the sense that the recurrence of cells containing information from an individual user is not periodic. ATM is used for transmission of integrated services, broadband switching and multiplexing with high-performance and cost-effectiveness under certain QoS guarantees.
ATM-ARP (ATM Address Resolution Protocol)
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An address resolution protocol for mapping ATM and IP addresses (each host is assigned a unique IP address). It can be used for discovering LAN hosts attached to an ATM network or in classical IP over ATM.
Attenuation
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Signal power loss through equipment, lines or other transmission devices. Measured in decibels.
AWG
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The American Wire Gauge System, which specifies wire width.
Backhaul
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Transporting traffic between distributed sites (typically access points) and more centralized points of presence. See Cellular Backhaul.
Bandwidth
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The range of frequencies passing through a given circuit. The greater the bandwidth, the more information can be sent through the circuit in a given amount of time.
Best effort
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A QoS class in which no specific traffic parameters and no absolute guarantee are provided. Best effort includes UBR and ABR.
Bit Interleaving /Multiplexing
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A process used in time division multiplexing where individual bits from different lower speed channel sources are combined (one bit from one channel at a time) into one continuous higher speed bit stream.
Bridge
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A device interconnecting local area networks at the OSI Data Link Layer, filtering and forwarding frames according to media access control (MAC) addresses.
Wideband technology capable of supporting voice, video and data, possibly using multiple channels.
BSC (Base Station Controller)
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Provides the intelligence behind the BTSs. Typically a BSC has 10s or even 100s of BTSs under its control. The BSC handles allocation of radio channels, receives measurements from the mobile phones, and controls handovers from BTS to BTS (except in the case of an inter-BSC handover in which case control is in part the responsibility of the anchor MSC). A key function of the BSC is to act as a concentrator where many different low capacity connections to BTSs (with relatively low utilization) become reduced to a smaller number of connections towards the mobile switching center (MSC) with a high level of utilization.
BTS (Base Transceiver Station)
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The equipment which facilitates the wireless communication between a user’s handset and the network. BTS can also be referred to as RBS (radio base station), Node B (in 3G networks) or simply BS (base station). Typically a BTS will have several transceivers (TRXs), which allow it to serve several different frequencies and different sectors of the cell. The BTS includes equipment for encrypting and decrypting communications with the base station controller (BSC).
Buffer
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A storage device. Commonly used to compensate for differences in data rates or event timing when transmitting from one device to another. Also used to remove jitter.
Buffering
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Used to compensate for differences in data rates or event timing when transmitting from one device to another. Also used to remove jitter.
Carrier Ethernet is a ubiquitous service based on standardized equipment and protocols providing seamless connectivity between high speed Ethernet-based LANs and WANs. Carrier Ethernet is characterized by industry-defined attributes for service level agreements, provisioning, system-wide management, and carrier-class OAM. Originally implemented in the core network, Carrier Ethernet is now being extended to the edge and access segment.
CBR (Constant Bit Rate)
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One of the five ATM classes of service. CBR supports the transmission of a continuous bit-stream of information, such as voice and video traffic, which require a constant amount of bandwidth allocated to a connection for the duration of the transmission.
CC (Continuity Cell)
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A cell used periodically to check whether a connection is idle or has failed. Continuity checking is one of the OAM function types for fault management.
CDV (Cell Delay Variation)
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A QoS parameter that measures the difference between the transfer delay of a single cell (CTD) and the expected transfer delay. This parameter is important for time-sensitive virtual circuits such as CBR and VBR-RT.
CDVT (Cell Delay Variation Tolerance)
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Used in CBR traffic, it specifies the acceptable tolerance of the CDV (jitter).
Cell
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The 53-byte basic information unit within an ATM network. The user traffic is segmented into cells at the source and reassembled at the destination. An ATM cell consists of a 5-byte ATM header and a 48-byte ATM payload, which contains the user data.
Channelized T1/E1
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T1 or E1 service that is divided into individual 64 kbps channels (or channels that are multiples of 64 kbps such as a 256 kbps channel made from four 64 kbps channels), as opposed to unchannelized service, which uses the entire bandwidth of the T1 (1.544 Mbps) or E1 (2.048 Mbps). Channelized T1 or E1 lines can consist of switched lines with in-band signaling or leased lines.
CI (Congestion Indicator)
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A field in the RM-cell that indicates congestion in the network which can ultimately lead to the source reducing its allow cell rate (ACR).
CIF (Cell Information Field)
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The payload (48 bytes) of the ATM cell.
CIR (Committed Information Rate)
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A term used in Frame Relay, which defines the information rate that the network is committed to provide to the user, under any network conditions.
A connection over a virtual circuit-based network providing service to the end users that is indistinguishable from a real point-to point, fixed-bandwidth circuit. Services based on circuit emulation (Circuit Emulation Services or CES) offer traditional TDM trunking (at n x 64 kbps, fractional T1/E1, T1/E1 or T3/E3) over a range of transport protocols, including ATM, Internet Protocol (IP), MPLS and Ethernet.
Circuit Emulation Service
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New technology for offering circuit emulation services over packet-switched networks. The service offers traditional TDM trunking (at n x 64 kbps, fractional E1/T1, E1/T1 or E3/T3) over a range of transport protocols, including Internet Protocol (IP), MPLS and Ethernet.
Clock
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A term for the source(s) of timing signals used in synchronous transmission.
Congestion control
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A resource and traffic management mechanism to avoid and/or prevent excessive situations (buffer overflow, insufficient bandwidth) that can cause the network to collapse. In ATM networks, congestion control schemes may be based on fields within the ATM cell header (CLP, EFCI within the PTI) or may be based on a more sophisticated mechanism between the ATM end-system and ATM switches. The ATM Forum has developed a mechanism based on rate control for ABR-type traffic. In Frame Relay networks, congestion is handled by the FECN, BECN and DE bits.
Data
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Information represented, in digital form, including voice, text, facsimile and video.
dB (Decibel)
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A unit used to measure relative increase or decrease in power, voltage or current, using a logarithmic scale.
dBm
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A measure of power in communications: the decibel in reference to one milliwatt (0 dBm = 1 milliwatt and -30 dBm = .001 milliwatt).
Digital Circuit Multiplication Equipment (DCME) performs voice compression over TDM and IP networks to reduce bandwidth requirements for microwave, wireline and costly satellite links while preserving voice quality.
DS0 (Digital Subscriber Level Zero)
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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
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Framing specification used in transmitting digital signals at 1.544 Mbps on a T1 facility or 2.048 Mbps on an E1 facility.
DS2 Channel
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For a T1 line, a 6.312 Mbps channel that consists of four DS1 channels; for an E1 line, an 8.45 Mbps channel that consists of four DS1 channels.
DS3 Channel
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A 44.736 Mbps line consisting of seven DS2 channels. A DS3 line is also called a T3 line.
DSL (Digital Subscriber Line)
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A modem technology for transmitting information at high speeds on existing copper phone lines to homes and businesses. DSL operates over existing copper telephone lines and requires runs of usually less than 20,000 feet to a central telephone office. Types of DSL include asymmetric DSL (ADSL), symmetric DSL (SDSL), high-bitrate DSL (HDSL) and the latest, symmetric high-bitrate DSL (SHDSL).
A 2.048 Mbps line, common in Europe, that supports thirty-two 64 kbps channels, each of which can transmit and receive data or digitized voice. The line uses framing and signaling to achieve synchronous and reliable transmission. The most common configurations for E1 lines are E1 PRI, and unchannelized E1.
Combining (bonding) multiple PPP (Point-to-Point Protocol) links between two systems into one logical data pipe. MLPPP is a standard IETF protocol.
E3
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The European standard for high speed digital transmission, operating at 34 Mbps.
Echo Cancellation
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Echo cancellation improves the quality of voice transmissions. It eliminates the echo that results from the reflection of the telephony signal back to the caller, which can occur in a 4-wire to 2-wire hybrid connection between the VFRAD and the telephones or PBX. The longer it takes the signals to return to the caller, the more perceptible the echo.
Echo-Signal
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Distortion occurring when a transmitted signal is echoed back (reflected) to the originating station.
EFM Ethernet in the First Mile (also known as IEEE 802.3ah)
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A collection of protocols specified in IEEE 802.3, defining Ethernet in the access networks, i.e. First/Last Mile. EFM also addresses other issues required for mass deployment of Ethernet services, such as operations, administration and maintenance (OAM) and compatibility with existing technologies (e.g. spectral compatibility for copper).
Encapsulation
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Encapsulating data is a technique used by layered protocols in which a low level protocol accepts a message from a higher level protocol, then places it in the data portion of the lower-level frame. The logistics of encapsulation require that packets traveling over a physical network contain a sequence of headers.
Ethernet
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Most popular local area network (LAN) technology in use today. All stations on the LAN share the total bandwidth, which is at speeds of 10 Mbps (Ethernet), 100 Mbps (Fast Ethernet), or 1000 Mbps (Gigabit Ethernet).
Ethernet OAM (Operation, Administration and Maintenance) is a set of functions designed to monitor network operation in order to detect network faults and measure its performance. Carrier-class Ethernet services require automated end-to-end management and monitoring, including OAM capabilities such as connectivity verification, fault detection, performance monitoring, and alarm indication.
Ethernet over SDH or SONET
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Although SDH and SONET networks were originally engineered to transport voice traffic, many carriers are using their ubiquitous SDH and SONET infrastructure to deploy Ethernet services. Recent developments in Next Generation SDH/SONET have made these networks more cost-effective and "user friendly" for Ethernet traffic.
Evolved HSPA, also known as MIMO (multiple-input multiple-output) HSPA, HSPA Evolution and HSPA+, is an upgrade to the 3GPP’s HSPA standard providing theoretical downlink speeds of up to 42 Mbps. HSPA+ is generally regarded as an interim phase between the 3.5G HSPA technology and 4G LTE (long-term evolution).
FCC (Federal Communications Commission)
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The regulatory agency established in the United States for all interstate radio and electronic communications.
Frame
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A logical grouping of information sent as a link layer unit over a transmission medium. The terms packet, datagram, segment and message are also used to describe logical information groupings.
Full Duplex
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A circuit or device permitting transmission in two directions (sending and receiving) at the same time.
Gateway
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Gateways are points of entrance and exit from a communications network. Viewed as a physical entity, a gateway is that node that translates between two otherwise incompatible networks or network segments. Gateways perform code and protocol conversion to facilitate traffic between data highways of differing architecture.
Grooming
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In telecommunications, the process of separating and segregating channels by combing, such that the broadest channel possible can be assembled and sent across the longest practical link. The aim is to minimize de-multiplexing traffic and reshuffling it electrically.
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.
A G.SHDSL modem is a customer located transceiver, connecting users to a G.SHDSL service via the local DSLAM.
GSM (Global System for Mobile communications)
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A second generation digital cellular telecommunication system originating in Europe, but now considered the international standard.
HDSL (High Bit-Rate Digital Subscriber Line)
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A high performance twisted pair transmission technology, best known as an enhanced transport mechanism for T1 or E1 service. It is designed for the Local Loop between a customer’s premises and an area exchange central office.
Idle Disconnects
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The breaking or release of a circuit connecting two telephones or data devices that occurs when no data is transmitted on a link in a specified amount of time.
IEEE (Institute of Electrical and Electronic Engineers)
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An international professional society issuing its own standards. The IEEE is a member of ANSI and ISO.
IETF (Internet Engineering Task Force)
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Body which was initially responsible for developing the specifications required for the interoperable implementation of IP.
IMA (Inverse Multiplexing over ATM)
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A method to pass ATM traffic over multiple E1/T1 links while keeping the ATM’s quality of service and optimization of bandwidth usage.
In-band Signaling
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The transmission of signaling information over the same path as data and/or voice information. Another term for in-band signaling is robbed-bit signaling. Robbed-bit refers to the 8 kbps of each channel used for signaling. T1 access lines containing one or more switched channels, and switched-56 lines use in-band signaling.
A method in which the inverse multiplexer slices the data stream into equal portions and transmits each portion over an available circuit. The receiving end adjusts for network-induced delay and reassembles the data packets into their proper order. Therefore, an inverse multiplexer allows lower speed channels across a network to be combined into a single, higher speed data stream.
IP (Internet Protocol)
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A networking protocol for providing a connectionless service to the higher transport protocol. It is responsible for discovering and maintaining topology information and for routing packets across homogeneous networks. Combined with TCP, it is commonly known as the TCP/IP platform.
ITU (International Telecommunication Union)
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A European-based, international advisory committee recommending worldwide standards for transmission.
Jitter
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The deviation of a transmission signal in time or phase. It can introduce errors and loss of synchronization in high speed synchronous communications.
Jitter Buffer
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Variation in the arrival times between packets, also called jitter, causes unnatural-sounding voice instead of a smooth voice stream. If a packet does not arrive in time to fit into the voice stream, the previous packet is replayed. This can seriously detract from voice quality. Since the jitter buffer adds to the overall delay of voice transmissions, the optimal jitter buffer should fit the network's differential delay. Adaptive jitter buffering continuously monitors the network delay and adjusts the queuing period accordingly.
Last Mile
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(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.
Latency
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The time between initiating a request for data and the beginning of the actual data transfer. Network latency is the delay introduced when a packet is momentarily stored, analyzed and then forwarded.
Leased Line
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A permanent telephone connection between two points that is rented for exclusive use from a telecommunications common carrier. In contrast to a normal dial-up connection, a leased line is always active. Typically, the highest speed data connections require a leased line connection. For example, a T1 channel is a type of leased line that provides a maximum transmission speed of 1.544 Mbps.
Loopback
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A type of diagnostic test in which the transmitted signal is returned to the sending device after passing through all or part of a communications link or network.
MAC (Media Access Control)
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A protocol that defines the way workstations gain access to transmission media, most widely used in reference to LANs. For IEEE LANs, the MAC layer is the lower sublayer of the data link layer protocol.
MAN (Metropolitan Area Network)
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A network that provides regional connectivity within a metropolitan area (such as a city).
Master Clock
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The source of timing signals (or the signals themselves) that all network stations use for synchronization.
MEF (Metro Ethernet Forum)
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A non-profit organization chartered with the mission of accelerating the adoption of optical Ethernet as the technology of choice in future metro networks worldwide. Ethernet was chosen for its relative simplicity and popularity with end-users, as well as for lowering costs of Ethernet equipment.
Mobile Backhaul
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The infrastructure and technologies connecting wireless base stations and Node Bs to base station controllers and radio network controllers, respectively, as well as the links between the controllers and the core network.
MPLS (Multiprotocol Label Switching)
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A standards-approved technology that allows core network routers to operate at higher speeds without needing to examine each packet in detail, allows more complex services to be developed, enabling discrimination on a QoS basis. MPLS speeds up network traffic flow by bringing Layer 2 information to Layer 3 (IP) and facilitating network management. It forwards traffic using a label that instructs the routers and the switches in the network where to forward the packets based on pre-established IP routing information. MPLS is called multiprotocol because it works with the IP, ATM, and Frame Relay network protocols.
Multiplexer (Mux)
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A device allowing two or more signals to pass over and share a common transmission path simultaneously.
Network
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(1) An interconnected group of nodes. (2) A series of points, nodes, or stations connected by communications channels; the collection of equipment through which connections are made between data stations.
Node
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A point of interconnection to a network.
OAM (Operation Administration and Maintenance)
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A set of network management functions that provide for network fault and performance management, analysis and fault isolation. OAM functions exist in carrierclass TDM and ATM networks, but are now also being implemented in MPLS and Ethernet networks. These capabilities will provide the basic tools for carriers to monitor, diagnose, and troubleshoot first-mile Ethernet access links.
Packet
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An ordered group of data and control signals transmitted through a network, as a subset of a larger message.
Packet Switching
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A data transmission technique, which divides user information into discrete data envelopes called packets, and sends the information packet by packet.
PCM (Pulse Code Modulation)
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A procedure for adapting an analog signal (such as voice) into a 64 kbps digital bit stream for transmission.
PON (Passive Optical Network)
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A high bandwidth, point-to-multipoint optical fiber network based on ATM, Ethernet or TDM. In this type of optical network, wavelengths of light are divided into timeslots so that each wavelength can be shared by a number of users. With PONs, a single fiber from the carrier’s exchange can service 16, 32 or more buildings through the use of both passive devices to split the optical signal, and PON protocols to control the sending and transmission of signals across the shared access facility.
Pseudowire
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Point-to-point connections set up between pairs of Provider Edge routers. Their primary function is to emulate (typically layer 2) native services like ATM, Frame Relay, Ethernet, low-rate TDM, or SONET/SDH over an underlying common packet switched network (MPLS, IP, or L2TPv3) network core. To achieve this, each of these technologies is encapsulated into a common MPLS format. Pseudowires are defined by the IETF PWE3 (Pseudowire Edge to Edge Emulation) WG.
QoS (Quality of Service)
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Refers to the capability of a network to provide better service to selected network traffic over various technologies, including Frame Relay, Asynchronous Transfer Mode (ATM), Ethernet and 802.1 networks.
SDH (Synchronous Data Hierarchy)
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The European standard for using optical media as the physical transport for high speed long-haul networks.
SHDSL, (ITU-T G.991.2, Single-pair High-speed Digital Subscriber Line), is a standardized method of extending the range of copper telephone lines for broadband services. SHDSL technology is used to 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 SHDSL standard is SHDSL.bis. Based on ITU-T G.991 and ETSI TS 101524, SHDSL.bis uses TC-PM 16 or TC-PAM 32 line coding and multi-pair bonding technology to reach transmission rates up to 5.69 Mbps on 1 pair (2-wire) for a rate up to 22.8 Mbps over 8-wire.
Silence Suppression
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In a telephone conversation, only about 50% of the full duplex connection is used at any given time. This is generally because only one person talks while the other person listens. In addition, voice packets are not sent during interword pauses and natural pauses in the conversation, reducing the required bandwidth by another 10%. Silence suppression frees this 60% of bandwidth on the full duplex link for other voice or data transmissions.
SLA (Service Level Agreement)
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A formal negotiated agreement between customers and their service provider, or between service providers. It records the common understanding about services, priorities, responsibilities, guarantees, etc. with the main purpose to agree on the level of service. For example, it may specify the levels of availability, serviceability, performance, operation, or other attributes of the service like billing and even penalties in the case of violation of the SLA.
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.
Statistical Multiplexer (STM or STDM)
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A device connecting multiple channels to a single link by dynamically allocating timeslots to the channels based on their transmission activity.
Subrate Multiplexer
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At one end of a communications link, a device that combines several lower speed transmission channels into a single high speed channel. A multiplexer at the other end reverses the process. Sometimes called a mux. See Bit Interleaving/Multiplexer.
Synchronous Transmission
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Transmission in which data bits are sent at a fixed rate, with the transmitter and receiver synchronized.
A digital transmission link with a capacity of 1.544 Mbps used in North America. Typically channelized into 24 DS0s, each capable of carrying a single voice conversation or data stream. Uses two pairs of twisted pair wires.
Combining (bonding) multiple PPP (Point-to-Point Protocol) links between two systems into one logical data pipe. MLPPP is a standard IETF protocol.
TDMoIP®
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TDM over IP is a standards-based transport technology that extends voice, video or data circuits across packet-switched networks simply, transparently and economically. Acting as a pseudowire, TDMoIP is unique in that it supports the multiple signaling standards, OAM mechanisms and clock recovery features demanded by TDM networks for carrying voice-grade telephony channels. A simple alternative to VoIP, TDMoIP enables using legacy TDM equipment while facilitating a smooth migration to newer IP, Ethernet and MPLS networks. TDMoIP technology was developed and patented by RAD, and is found in RAD’s IPmux, Vmux and Megaplex products.
UMTS (Universal Mobile Telecommunications System) is a 3G mobile technology using W-CDMA (Wideband Code Division Multiple Access) air interface. Developed to support voice and broadband services, such as video telephony and video conferencing, UMTS offers data rates of up to 2 Mbps, compared to the 64 kbps bandwidth supported by 2G networks.
UNI (User Network Interface)
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The interface, defined as a set of protocols and traffic characteristics, between the CPE and the ATM network.
VBR (Variable Bit Rate)
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Traffic containing bursts but centered around an average bandwidth. VBR, divided into real-time (RT-VBR) and non-realtime (NRT-VBR) traffic, requires the same service guarantees (that is delay, cell loss and timing) provided by CBR.
Voice Compression
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Newer voice compression algorithms try to model 64 kpbs PCM (G.711) more efficiently using fewer bits to reduce the bandwidth required, while preserving the quality or audibility of the voice transmission. Vendors such as RAD support low bit rate voice compression algorithms such as ITU G.723.1 and G.729A to permit the greatest number of simultaneous multiple calls while maintaining high quality voice. In this way, compressed voice systems (CVS) can offer greater bandwidth savings, reduced network congestion and high quality voice transmissions.
VoIP (Voice over IP)
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Set of facilities for managing the delivery of voice information using the Internet Protocol (IP). Voice information is sent in digital form in discrete packets over the Internet instead of in analog form over the public switched telephone network (PSTN). A major advantage of VoIP is that it avoids the tolls charged by ordinary telephone service.
WAN (Wide Area Network)
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A network that typically spans nationwide distances and usually utilizes public telephone networks.
WDM (Wave Division Multiplexing)
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Optical transmission technique in which two or more wavelengths (each carrying its own information) are combined for transmission over a single optical fiber. At the receiving end, the wavelengths are separated and directed to separate receivers. Increases the capacity of data transmission over fiber optics. Also used to connect two fiber optic devices over a single strand of fiber.
Wireless Modem
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A modem that uses radio transmission technology to transmit data between remote locations. A wireless modem is often used by mobile clients in locations where access to a terrestrial connection is not feasible.
ITU-T standard Y.1731 is an Ethernet OAM (operations, administration and maintenance) standard for testing an Ethernet service and for monitoring its performance.
IEEE standard 1588-2008, previously known as pre-standard 1588v2, is the latest version of Precision Time Protocol (PTP) for frequency and time of day distribution over packet switched networks. It is based on timestamp information exchange in a master-slave hierarchy.
IEEE standard 1588v2, also known as 1588-2008, is the latest version of Precision Time Protocol (PTP) for frequency and time of day distribution over packet switched networks. It is based on timestamp information exchange in a master-slave hierarchy.
IEEE standard 802.1ag, also known as “Connectivity Fault Management (CFM)”, is an Ethernet OAM (operations, administration and maintenance) standard for testing an Ethernet service over any path, whether a single link or end-to-end.
IEEE standard 802.3-2005, also known as 802.3ah clause 57, is an Ethernet OAM (operations, administration and maintenance) standard for testing the status of a single Ethernet link within a network. It is also known as Ethernet Link OAM and EFM (Ethernet in the First Mile) OAM.
