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OSN 500 550 580 V100R008C50 Commissioning and Configuration Guide 02

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).


1 U
The standard electronics industries association (EIA) rack unit (44 mm/1.75 in.)
1+1 backup
A backup method in which two components mirror each other. If the active component goes down, the standby component takes over services from the active component to ensure that the system service is not interrupted.
1+1 hot standby
A backup mode in which two systems with the same functions are deployed, one in the active state and the other in the standby state with power on. The standby system backs up the data of the active system automatically. Once the active system encounters a fault, the standby system takes over services from the active system automatically or by manual intervention.
An Ethernet specification that uses the twisted pair cable with the transmission speed as 1000 Mbit/s and the transmission distance as 100 meters.
An Ethernet specification that uses the twisted pair cable with the transmission speed as 10 Mbit/s and the transmission distance as 100 meters.
two-way delay measurement
See Third Generation.
reshaping, retiming, regenerating
802.1Q in 802.1Q (QinQ)
A VLAN feature that allows the equipment to add a VLAN tag to a tagged frame. The implementation of QinQ is to add a public VLAN tag to a frame with a private VLAN tag to allow the frame with double VLAN tags to be transmitted over the service provider's backbone network based on the public VLAN tag. This provides a layer 2 VPN tunnel for customers and enables transparent transmission of packets over private VLANs.
See Authentication, Authorization and Accounting.
See ATM Adaptation Layer.
See available bit rate.
alternating current
associated channel header
See Access Control List.
allowed cell rate
add/drop multiplexer
See asymmetric digital subscriber line.
See assured forwarding.
alarm indication signal
AIS insertion
Insertion of AIS in a channel with excessive errors to indicate that it is unavailable. For a line board, it can be set whether to insert AIS when there are excessive errors in the B1, B2 and B3 bytes. For tributary board at the E1/T1 level, it can be set whether to insert AIS when there are excessive errors in BIP-2. For tributary board at the E3 level or higher, it can be set whether to insert AIS when there are excessive errors in the B3 byte.
See automatic laser shutdown.
See alternate mark inversion.
See avalanche photodiode.
See application programming interface.
access point identifier
automatic protection switching
See Address Resolution Protocol.
See autonomous system.
American Standard Code for Information Interchange
See application-specific integrated circuit.
automatically switched optical network
attribute discovery
ATM Adaptation Layer (AAL)
An interface between higher-layer protocols and Asynchronous Transfer Mode (ATM). The AAL provides a conversion function to and from ATM for various types of information, including voice, video, and data.
See automatic transmit power control.
See administrative unit group.
Access Control List (ACL)
A list of entities, together with their access rights, which are authorized to access a resource.
Address Resolution Protocol (ARP)
An Internet Protocol used to map IP addresses to MAC addresses. The ARP protocol enables hosts and routers to determine link layer addresses through ARP requests and responses. The address resolution is a process by which the host converts the target IP address into a target MAC address before transmitting a frame. The basic function of ARP is to use the target equipment's IP address to query its MAC address.
Authentication, Authorization and Accounting (AAA)
A mechanism for configuring authentication, authorization, and accounting security services. Authentication refers to the verification of user identities and the related network services; authorization refers to the granting of network services to users according to authentication results; and accounting refers to the tracking of the consumption of network services by users.
administrative unit group (AUG)
One or more administrative units occupying fixed, defined positions in an STM payload. An AUG consists of AU-4s.
aging time
The time to live before an object becomes invalid.
alarm cascading
The method of cascading alarm signals from several subracks or cabinets.
alarm indication
A mechanism to indicate the alarm status of equipment. On the cabinet of an NE, four differently-colored indicators specify the current status of the NE. When the green indicator is on, the NE is powered on. When the red indicator is on, a critical alarm has been generated. When the orange indicator is on, a major alarm has been generated. When the yellow indicator is on, a minor alarm has been generated. The ALM alarm indicator on the front panel of a board indicates the current status of the board.
alarm masking
A method to mask alarms for the alarm management purpose. Alarms that are masked are not displayed on the NMS or the NMS does not monitor unimportant alarms.
alarm suppression
A method to suppress alarms for the alarm management purpose. Alarms that are suppressed are no longer reported from NEs.
alternate mark inversion (AMI)
A synchronous clock encoding technique which uses bipolar pulses to represent logical 1 values.
application programming interface (API)
An application programming interface is a particular set of rules and specifications that are used for communication between software programs.
application-specific integrated circuit (ASIC)
A special type of chip that starts out as a nonspecific collection of logic gates. Late in the manufacturing process, a layer is added to connect the gates for a specific function. By changing the pattern of connections, the manufacturer can make the chip suitable for many needs.
assured forwarding (AF)
One of the four per-hop behaviors (PHB) defined by the Diff-Serv workgroup of IETF. It is suitable for certain key data services that require assured bandwidth and short delay. For traffic within the bandwidth limit, AF assures quality in forwarding. For traffic that exceeds the bandwidth limit, AF degrades the service class and continues to forward the traffic instead of discarding the packets.
asymmetric digital subscriber line (ADSL)
A technology for transmitting digital information at a high bandwidth on existing phone lines to homes and businesses. Unlike regular dialup phone service, ADSL provides continuously-available, "always on" connection. ADSL is asymmetric in that it uses most of the channel to transmit downstream to the user and only a small part to receive information from the user. ADSL simultaneously accommodates analog (voice) information on the same line. ADSL is generally offered at downstream data rates from 512 kbit/s to about 6 Mbit/s.
Reduction of signal magnitude or signal loss, usually expressed in decibels.
A device used to increase the attenuation of an Optical Fiber Link. Generally used to ensure that the signal at the receive end is not too strong.
automatic laser shutdown (ALS)
A technique (procedure) to automatically shutdown the output power of laser transmitters and optical amplifiers to avoid exposure to hazardous levels.
automatic transmit power control (ATPC)
A method of adjusting the transmit power based on fading of the transmit signal detected at the receiver
autonomous system (AS)
A network set that uses the same routing policy and is managed by the same technology administration department. Each AS has a unique identifier that is an integer ranging from 1 to 65535. The identifier is assigned by IANA. An AS can be divided into areas.
available bit rate (ABR)
A kind of service categories defined by the ATM forum. ABR only provides possible forwarding service and applies to the connections that does not require the real-time quality. It does not provide any guarantee in terms of cell loss or delay.
avalanche photodiode (APD)
A semiconductor photodetector with integral detection and amplification stages. Electrons generated at a p/n junction are accelerated in a region where they free an avalanche of other electrons. APDs can detect faint signals but require higher voltages than other semiconductor electronics.
See broadband integrated services digital network.
booster amplifier
2 x booster amplifier
background block error
boundary clock
binary coded decimal
See backward defect indication.
See best effort.
backward error indication
See basic encoding rule.
See Bidirectional Forwarding Detection.
Border Gateway Protocol
backward incoming alignment error
See basic input/output system.
See bit interleaved parity.
See bit interleaved parity-8.
See building integrated timing supply.
best master clock
See Bayonet-Neill-Concelman.
bill of materials
See bridge protocol data unit.
board protection switching
See basic rate access.
See broadband remote access server.
binary synchronous communication
base transceiver station
broadband TV
backbone wavelength division multiplexing system
Bayonet-Neill-Concelman (BNC)
A connector used for connecting two coaxial cables.
Bidirectional Forwarding Detection (BFD)
A fast and independent hello protocol that delivers millisecond-level link failure detection and provides carrier-class availability. After sessions are established between neighboring systems, the systems can periodically send BFD packets to each other. If one system fails to receive a BFD packet within the negotiated period, the system regards that the bidirectional link fails and instructs the upper layer protocol to take actions to recover the faulty link.
An electronic circuit board containing circuits and sockets into which additional electronic devices on other circuit boards or cards can be plugged.
Process of copying data to another storage area so that it can be used to restore the data when the source data is damaged or lost.
backward defect indication (BDI)
A function that the sink node of a LSP, when detecting a defect, uses to inform the upstream end of the LSP of a downstream defect along the return path.
basic encoding rule (BER)
A rule in the syntax structure of the ASN.1, which describes how data is represented during transmission.
basic input/output system (BIOS)
Firmware stored on the computer motherboard that contains basic input/output control programs, power-on self test (POST) programs, bootstraps, and system setting information. The BIOS provides hardware setting and control functions for the computer.
basic rate access (BRA)
An ISDN interface typically used by smaller sites and customers. This interface consists of a single 16 kbit/s data (or "D") channel plus two bearer (or "B") channels for voice and/or data. Also known as Basic Rate Access, or BRI.
best effort (BE)
A traditional IP packet transport service. In this service, the diagrams are forwarded following the sequence of the time they reach. All diagrams share the bandwidth of the network and routers. The amount of resource that a diagram can use depends of the time it reaches. BE service does not ensure any improvement in delay time, jitter, packet loss ratio, and high reliability.
bit interleaved parity (BIP)
A method of error monitoring. With even parity, the transmitting equipment generates an X-bit code over a specified portion of the signal in such a manner that the first bit of the code provides even parity over the first bit of all X-bit sequences in the covered portion of the signal, the second bit provides even parity over the second bit of all X-bit sequences within the specified portion, and so forth. Even parity is generated by setting the BIP-X bits so that an even number of 1s exist in each monitored partition of the signal. A monitored partition comprises all bits in the same bit position within the X-bit sequences in the covered portion of the signal. The covered portion includes the BIP-X.
bit interleaved parity-8 (BIP-8)
Consists of a parity byte calculated bit-wise across a large number of bytes in a transmission transport frame. Divide a frame is into several blocks with 8 bits (one byte) in a parity unit and then arrange the blocks in matrix. Compute the number of "1" or "0" over each column. Then fill a 1 in the corresponding bit for the result if the number is odd, otherwise fill a 0.
bound path
A parallel path with several serial paths bundled together. It improves the data throughput capacity.
bridge protocol data unit (BPDU)
Data messages exchanged across switches within an extended LAN that uses a spanning tree protocol (STP) topology. BPDU packets contain information on ports, addresses, priorities, and costs, and they ensure that the data reaches its intended destination. BPDU messages are exchanged across bridges to detect loops in a network topology. These loops are then removed by shutting down selected bridge interfaces and placing redundant switch ports in a backup, or blocked, state.
broadband integrated services digital network (B-ISDN)
A standard defined by the ITU-T to handle high-bandwidth applications, such as voice. It currently uses the ATM technology to transmit data over SONNET-based circuits at 155 to 622 Mbit/s or higher speed.
broadband remote access server (BRAS)
A new type of access gateway for broadband networks. As a bridge between backbone networks and broadband access networks, BRAS provides methods for fundamental access and manages the broadband access network. It is deployed at the edge of network to provide broadband access services, convergence, and forwarding of multiple services, meeting the demands for transmission capacity and bandwidth utilization of different users. BRAS is a core device for the broadband users' access to a broadband network.
A means of delivering information to all members in a network. The broadcast range is determined by the broadcast address.
building integrated timing supply (BITS)
In the situation of multiple synchronous nodes or communication devices, one can use a device to set up a clock system on the hinge of telecom network to connect the synchronous network as a whole, and provide satisfactory synchronous base signals to the building integrated device. This device is called BITS.
built-in WDM
A function which integrates some simple WDM systems into products that belong to the OSN series. That is, the OSN products can add or drop several wavelengths directly.
A process of forming data into a block of the proper size, uninterruptedly sending the block in a fast operation, waiting for a long time, and preparing for the next fast sending.
A path or channel for signal transmission. The typical case is that, the bus is an electrical connection that connects one or more conductors. All devices that are connected to a bus, can receive all transmission contents simultaneously.
See connection admission control.
capital expenditure
committed access rate
See channel associated signaling.
See client automatic upgrade.
See committed burst size.
See continuity check.
connection control interface
Consultative Committee of International Telegraph and Telephone
continuity check message
See Common Channel Signaling.
A 3G technology developed by Qualcomm of the US. Technology competitive with WCDMA, upgraded from CDMA1, and developed by the GSM community as a worldwide standard for 3G mobile.
cell delay variation tolerance
See customer edge.
See circuit emulation service.
compact flash
connectivity fault management
cell fill rate
Cisco Group Management Protocol
committed information rate
International Special Committee on Radio Interference
See Common and Internal Spanning Tree.
common language equipment identification
clock board
connectionless network protocol
See cell loss priority.
connection monitoring end point
coded mark inversion
cell misinsertion ratio
See central processing unit.
Connection Request
Constraint-based Routed Label Distribution Protocol
See cyclic redundancy check.
CRC-4 multiframe
A multiframe recommended by ITU-T G.704 and set up based on the first bit of timeslot 0. The CRC-4 multiframe is different from the CAS multiframe in principle and implementation. Each CRC-4 multiframe contains 16 PCM frames. Each CRC-4 multiframe consists of two CRC-4 sub-multiframes. Each CRC-4 sub-multiframe is a CRC-4 check block that contains 2048 (256 x 8) bits. Bits C1 to C4 of a check block can check the previous check block.
Canadian Standards Association
consecutive severely errored second
Client Signal Fail
See carrier sense multiple access with collision detection.
Constrained Shortest Path First
See common spanning tree.
common transmit clock
connection termination point
connectivity verification
control word
See coarse wavelength division multiplexing.
class of service
Common Channel Signaling (CCS)
A signaling system used in telephone networks that separates signaling information from user data. A specified channel is exclusively designated to carry signaling information for all other channels in the system.
Common and Internal Spanning Tree (CIST)
The single spanning tree jointly calculated by STP and RSTP, the logical connectivity using MST bridges and regions, and MSTP. The CIST ensures that all LANs in the bridged local area network are simply and fully connected.
called number
The number dialed by the subscriber to originate a call.
carrier sense multiple access with collision detection (CSMA/CD)
Carrier sense multiple access with collision detection (CSMA/CD) is a computer networking access method in which:a carrier sensing scheme is used. a transmitting data station that detects another signal while transmitting a frame, stops transmitting that frame, transmits a jam signal, and then waits for a random time interval before trying to send that frame again.
cell loss priority (CLP)
A field in the ATM cell header that determines the probability of a cell being dropped if the network becomes congested. Cells with CLP = 0 are insured traffic, which is unlikely to be dropped. Cells with CLP = 1 are best-effort traffic, which might be dropped.
central processing unit (CPU)
The computational and control unit of a computer. The CPU is the device that interprets and executes instructions. The CPU has the ability to fetch, decode, and execute instructions and to transfer information to and from other resources over the computer's main data-transfer path, the bus.
channel associated signaling (CAS)
A signaling system in which signaling information is transmitted within a dedicated voice channel. China Signaling System No. 1 is a type of CAS signaling.
circuit emulation service (CES)
A function with which the E1/T1 data can be transmitted through ATM networks. At the transmission end, the interface module packs timeslot data into ATM cells. These ATM cells are sent to the reception end through the ATM network. At the reception end, the interface module re-assigns the data in these ATM cells to E1/T1 timeslots. The CES technology guarantees that the data in E1/T1 timeslots can be recovered to the original sequence at the reception end.
client automatic upgrade (CAU)
A function that enables a user to automatically detect the update of the client version and upgrade the client. This keeps the version of the client is the same as that of the server.
coarse wavelength division multiplexing (CWDM)
A signal transmission technology that multiplexes widely-spaced optical channels into the same fiber. CWDM spaces wavelengths at a distance of several nm. CWDM does not support optical amplifiers and is applied in short-distance chain networking.
committed burst size (CBS)
A parameter used to define the capacity of token bucket C, that is, the maximum burst IP packet size when information is transferred at the committed information rate. This parameter must be greater than 0 but should be not less than the maximum length of an IP packet to be forwarded.
common spanning tree (CST)
A single spanning tree that connects all the MST regions in a network. Every MST region is considered as a switch; therefore, the CST can be considered as their spanning tree generated with STP/RSTP.
Extra intra-network or inter-network traffic resulting in decreased network service efficiency.
connection admission control (CAC)
A control process in which the network takes actions in the call set-up phase (or call re-negotiation phase) to determine which connection request is admitted.
continuity check (CC)
An Ethernet connectivity fault management (CFM) method used to detect the connectivity between MEPs by having each MEP periodically transmit a Continuity Check Message (CCM).
The connection of channels between the tributary board and the line board, or between line boards inside the NE. Network services are realized through the cross-connections of NEs.
customer edge (CE)
A part of the BGP/MPLS IP VPN model that provides interfaces for directly connecting to the Service Provider (SP) network. A CE can be a router, switch, or host.
cyclic redundancy check (CRC)
A procedure used to check for errors in data transmission. CRC error checking uses a complex calculation to generate a number based on the data transmitted. The sending device performs the calculation before performing the transmission and includes the generated number in the packet it sends to the receiving device. The receiving device then repeats the same calculation. If both devices obtain the same result, the transmission is considered to be error free. This procedure is known as a redundancy check because each transmission includes not only data but extra (redundant) error-checking values.
digital-analog converter
destination access point identifier
See DC-return common (with ground).
See DC-return isolate (with ground).
DC-return common (with ground) (DC-C)
A power system, in which the BGND of the DC return conductor is short-circuited with the PGND on the output side of the power supply cabinet and also on the line between the output of the power supply cabinet and the electric equipment.
DC-return isolate (with ground) (DC-I)
A power system, in which the BGND of the DC return conductor is short-circuited with the PGND on the output side of the power supply cabinet and is isolated from the PGND on the line between the output of the power supply cabinet and the electric equipment.
data carrier detect
See data circuit-terminating equipment.
data communication function
See dispersion compensation module.
See data communication network.
digital distribution frame
See digital data network.
See Dynamic Host Configuration Protocol.
DIP switch
dual in-line package switch
See distributed link aggregation group.
See delay measurement.
delay measurement message
delay measurement reply
dual node interconnection
dynamic random database
dynamic rate repartitioning
differential phase return to zero
See differentiated services code point.
See digital subscriber line access multiplexer.
digital signal processing
data set ready
door status switch
See data terminal equipment.
See dual tone multiple frequency.
data terminal ready
See digital video broadcasting.
digital video broadcast-asynchronous serial interface
See Distance Vector Multicast Routing Protocol.
See dense wavelength division multiplexing.
See differentiated service.
Distance Vector Multicast Routing Protocol (DVMRP)
An Internet gateway protocol based primarily on the RIP. The DVMRP protocol implements a typical dense mode IP multicast solution and uses IGMP to exchange routing datagrams with its neighbors.
Dynamic Host Configuration Protocol (DHCP)
A client-server networking protocol. A DHCP server provides configuration parameters specific to the DHCP client host requesting information the host requires to participate on the Internet network. DHCP also provides a mechanism for allocating IP addresses to hosts.
data circuit-terminating equipment (DCE)
The equipment that provides the signal conversion and coding between the data terminal equipment (DTE) and the line. A DCE is located at a data station. The DCE may be separate equipment, or an integral part of the DTE or intermediate equipment. The DCE may perform other functions that are normally performed at the network end of the line.
data communication network (DCN)
A communication network used in a TMN or between TMNs to support the data communication function.
data terminal equipment (DTE)
A user device composing the UNI. The DTE accesses the data network through the DCE equipment (for example, a modem) and usually uses the clock signals produced by DCE.
delay measurement (DM)
The time elapsed since the start of transmission of the first bit of the frame by a source node until the reception of the last bit of the loopbacked frame by the same source node, when the loopback is performed at the frame's destination node.
dense wavelength division multiplexing (DWDM)
The technology that utilizes the characteristics of broad bandwidth and low attenuation of single mode optical fiber, employs multiple wavelengths with specific frequency spacing as carriers, and allows multiple channels to transmit simultaneously in the same fiber.
differentiated service (DiffServ)
An IETF standard that defines a mechanism for controlling and forwarding traffic in a differentiated manner based on CoS settings to handle network congestion.
differentiated services code point (DSCP)
According to the QoS classification standard of the Differentiated Service (Diff-Serv), the type of services (ToS) field in the IP header consists of six most significant bits and two currently unused bits, which are used to form codes for priority marking. Differentiated services code point (DSCP) is the six most important bits in the ToS. It is the combination of IP precedence and types of service. The DSCP value is used to ensure that routers supporting only IP precedence can be used because the DSCP value is compatible with IP precedence. Each DSCP maps a per-hop behavior (PHB). Therefore, terminal devices can identify traffic using the DSCP value.
digital data network (DDN)
A data transmission network that is designed to transmit data on digital channels (such as the fiber channel, digital microwave channel, or satellite channel).
digital subscriber line access multiplexer (DSLAM)
A network device, usually situated in the main office of a telephone company, that receives signals from multiple customer Digital Subscriber Line (DSL) connections and uses multiplexing techniques to put these signals on a high-speed backbone line.
digital video broadcasting (DVB)
A suite of internationally accepted open standards for digital television. DVB standards are maintained by the DVB Project, an international industry consortium with more than 300 members, and they are published by a Joint Technical Committee (JTC) of European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC) and European Broadcasting Union (EBU).
The maximum error of the local clock compared with the reference clock.
dispersion compensation module (DCM)
A type of module that contains dispersion compensation fibers to compensate for the dispersion of the transmitting fiber.
distributed link aggregation group (DLAG)
A board-level port protection technology that detects unidirectional fiber cuts and negotiates with the opposite port. In the case of a link down failure on a port or hardware failure on a board, services are automatically switched to the slave board, thereby achieving 1+1 protection for the inter-board ports.
In an access network, the direction of transmission toward the subscriber end of the link.A direction of message forwarding within a transaction that refers to the direction that requests flow from the user agent client to user agent server.
dual tone multiple frequency (DTMF)
Multi-frequency signaling technology for telephone systems. According to this technology, standard set combinations of two specific voice band frequencies, one from a group of four low frequencies and the other from a group of four high frequencies, are used.
See Ethernet aggregation.
See Ethernet local area network.
See Ethernet line.
See Ethernet-tree.
end to end
See excess burst size.
See embedded control channel.
See erbium-doped fiber amplifier.
Ethernet Electric Interface PMC Card
See electrically erasable programmable read-only memory.
See expedited forwarding.
explicit forward congestion indication
Ethernet in the First Mile
Ethernet in the first mile OAM
See Electronic Industries Alliance.
See excess information rate.
See electromagnetic compatibility.
early packet discard
See Ethernet private line.
See Ethernet private LAN service.
See Ethernet passive optical network.
Ethernet ring protection switching
See electric supervisory channel.
See enterprise system connection.
electrostatic discharge
See equipment serial number.
European Telecommunication Standards
See European Telecommunications Standards Institute.
See Ethernet virtual private line.
See Ethernet virtual private LAN service.
See experimental bits.
Electronic Industries Alliance (EIA)
An association based in Washington, D.C., with members from various electronics manufacturers. It sets standards for electronic components. RS-232-C, for example, is the EIA standard for connecting serial components.
See Ethernet over dual domains.
A LAN technology that uses the carrier sense multiple access with collision detection (CSMA/CD) media access control method. The Ethernet network is highly reliable and easy to maintain. The speed of an Ethernet interface can be 10 Mbit/s, 100 Mbit/s, 1000 Mbit/s, or 10,000 Mbit/s.
Ethernet aggregation (E-Aggr)
A type of Ethernet service that is based on a multipoint-to-point EVC (Ethernet virtual connection).
Ethernet line (E-Line)
A type of Ethernet service that is based on a point-to-point EVC (Ethernet virtual connection).
Ethernet local area network (E-LAN)
A type of Ethernet service that is based on a multipoint-to-multipoint EVC (Ethernet virtual connection).
Ethernet over dual domains (EoD)
A type of boards. EoD boards bridge the PSN and TDM networks, enabling Ethernet service transmission across PSN and TDM networks.
Ethernet passive optical network (EPON)
An Ethernet Passive Optical Network (EPON) is a passive optical network based on Ethernet. It is a new generation broadband access technology that uses a point-to-multipoint structure and passive fiber transmission. It supports upstream/downstream symmetrical rates of 1.25 Gbit/s and a reach distance of up to 20 km. In the downstream direction, the bandwidth is shared based on encrypted broadcast transmission for different users. In the upstream direction, the bandwidth is shared based on TDM. EPON meets the requirements for high bandwidth.
Ethernet private LAN service (EPLAN)
A type of Ethernet service provided by SDH, PDH, ATM, or MPLS server layer networks. This service is carried over dedicated bandwidth between multipoint-to-multipoint connections.
Ethernet private line (EPL)
A type of Ethernet service provided by SDH, PDH, ATM, or MPLS server layer networks. This service is carried over dedicated bandwidth between point-to-point connections.
Ethernet virtual private LAN service (EVPLAN)
A type of Ethernet service provided by SDH, PDH, ATM, or MPLS server layer networks. This service is carried over shared bandwidth between multipoint-to-multipoint connections.
Ethernet virtual private line (EVPL)
A type of Ethernet service provided by SDH, PDH, ATM, or MPLS server layer networks. This service is carried over shared bandwidth between point-to-point connections.
Ethernet-tree (E-Tree)
An Ethernet service type that is based on a Point-to-multipoint Ethernet virtual connection.
European Telecommunications Standards Institute (ETSI)
ETSI is a multinational standardization body with regulatory and standardization authority over much of Europe. GSM standardization took place under the auspices of ETSI.
A header field of the SIP message. It specifies the duration after which the message or message content expires.
enhanced small form-factor pluggable
The egress LER. The group is transferred along the LSP consisting of a series of LSRs after the group is labeled.
electric supervisory channel (ESC)
A technology that implements communication among all the nodes and transmission of monitoring data in an optical transmission network. The monitoring data of ESC is introduced into DCC service overhead and is transmitted with service signals.
electrically erasable programmable read-only memory (EEPROM)
A type of EPROM that can be erased with an electrical signal. It is useful for stable storage for long periods without electricity while still allowing reprograming. EEPROMs contain less memory than RAM, take longer to reprogram, and can be reprogramed only a limited number of times before wearing out.
electromagnetic compatibility (EMC)
A condition which prevails when telecommunications equipment is performing its individually designed function in a common electromagnetic environment without causing or suffering unacceptable degradation due to unintentional electromagnetic interference to or from other equipment in the same environment.
embedded control channel (ECC)
A logical channel that uses a data communications channel (DCC) as its physical layer to enable the transmission of operation, administration, and maintenance (OAM) information between NEs.
A technology for layered protocols, in which a lower-level protocol accepts a message from a higher-level protocol and places it in the data portion of the lower-level frame. Protocol A's packets have complete header information, and are carried by protocol B as data. Packets that encapsulate protocol A have a B header, an A header, followed by the information that protocol A is carrying. Note that A could equal to B, as in IP inside IP.
A function used to transform data so as to hide its information content to prevent it's unauthorized use.
enterprise system connection (ESCON)
A path protocol that connects the host to various control units in a storage system. Enterprise system connection is a serial bit stream transmission protocol that operates a rate of 200 Mbit/s.
equipment serial number (ESN)
A string of characters that identify a piece of equipment and ensures correct allocation of a license file to the specified equipment. It is also called "equipment fingerprint".
erbium-doped fiber amplifier (EDFA)
An optical device that amplifies optical signals. This device uses a short optical fiber doped with the rare-earth element, Erbium. The signal to be amplified and a pump laser are multiplexed into the doped fiber, and the signal is amplified by interacting with doping ions. When the amplifier passes an external light source pump, it amplifies the optical signals in a specific wavelength range.
excess burst size (EBS)
A parameter related to traffic. In the single rate three color marker (srTCM) mode, traffic control is achieved by token buckets C and E. The excess burst size parameter defines the capacity of token bucket E, that is, the maximum burst IP packet size when the information is transferred at the committed information rate. This parameter must be greater than 0 but should be not less than the maximum length of an IP packet to be forwarded.
excess information rate (EIR)
The bandwidth for excessive or burst traffic above the CIR; it equals the result of the actual transmission rate without the safety rate.
exercise switching
An operation to check whether the protection switching protocol functions properly. The protection switching is not really performed.
expedited forwarding (EF)
The highest order QoS in the Diff-Serv network. EF PHB is suitable for services that demand low packet loss ratio, short delay, and broad bandwidth. In all the cases, EF traffic can guarantee a transmission rate equal to or faster than the set rate. The DSCP value of EF PHB is "101110".
experimental bits (EXP)
A field in the MPLS packet header, three bits long. This field is always used to identify the CoS of the MPLS packet.
frame alignment signal
See Fibre Channel.
Federal Communications Commission
frame check sequence
See frequency division duplex.
See fiber distributed data interface.
See forward defect indication.
FDI packet
See forward defect indication packet.
See frame delay variation.
fast Ethernet
See forward error correction.
fast failure detection
See forwarding information base.
See Fibre Connect.
See first in first out.
See frame loss ratio.
See field programmable gate array.
See fast protection switching.
See frame relay.
See fast reroute.
See field replaceable unit.
File Transfer Protocol
Fibre Channel (FC)
A high-speed transport technology used to build SANs. FC is primarily used for transporting SCSI traffic from servers to disk arrays, but it can also be used on networks carrying ATM and IP traffic. FC supports single-mode and multi-mode fiber connections, and can run on twisted-pair copper wires and coaxial cables. FC provides both connection-oriented and connectionless services.
Fibre Connect (FICON)
A new generation connection protocol that connects the host to various control units. It carries a single byte command protocol through the physical path of fibre channel, and provides a higher transmission rate and better performance than ESCON.
fast protection switching (FPS)
A type of pseudo wire automatic protection switching (PW APS). When the working PW is faulty, the source transmits services to the protection PW and the sink receives the services from the protection PW. FPS generally works with the interworking function (IWF) to provide end-to-end protection for services.
fast reroute (FRR)
A technology which provides a temporary protection of link availability when part of a network fails. The protocol enables the creation of a standby route or path for an active route or path. When the active route is unavailable, the traffic on the active route can be switched to the standby route. When the active route is recovered, the traffic can be switched back to the active route. FRR is categorized into IP FRR, VPN FRR, and TE FRR.
fault alarm
A type of alarm caused by hardware and/or software faults, for example, board failure, or by the exception that occurs in major functions. After handling, a fault alarm can be cleared, upon which the NE reports a recovery alarm. Fault alarms are of higher severity than event alarms.
fiber distributed data interface (FDDI)
A standard developed by the American National Standards Institute (ANSI) for high-speed fiber-optic LANs. FDDI provides specifications for transmission rates of 100 megabits per second on token ring networks.
field programmable gate array (FPGA)
A semi-customized circuit that is used in the Application Specific Integrated Circuit (ASIC) field and developed based on programmable components. FPGA remedies many of the deficiencies of customized circuits, and allows the use of many more gate arrays.
field replaceable unit (FRU)
A unit or component of a system that is designed to be replaced in the field, i.e., without returning the system to a factory or repair depot.Field replaceable units may either be customer-replaceable or their replacement may require trained service personnel.
A security system consisting of a combination of hardware and software that limits the exposure of a computer or computer network to attack from crackers; commonly used on local area networks that are connected to the internet. Firewalls can be implemented in either hardware or software, or a combination of both.
first in first out (FIFO)
A stack management method in which data that is stored first in a queue is also read and invoked first.
forced switching
The action of switching traffic signals between a working channel and protection channel. The switching occurs even if the channel to which traffic is being switched is faulty or an equal or higher priority switching command is in effect.
forward defect indication (FDI)
A packet generated and traced forward to the sink node of the LSP by the node that first detects defects. It includes fields to indicate the nature of the defect and its location. Its primary purpose is to suppress alarms being raised at affected higher level client LSPs and (in turn) their client layers.
forward defect indication packet (FDI packet)
A packet that responds to the detected failure event. It is used to suppress alarms of the upper layer network where failure has occurred.
forward error correction (FEC)
A bit error correction technology that adds correction information to the payload at the transmit end. Based on the correction information, the bit errors generated during transmission can be corrected at the receive end.
forwarding information base (FIB)
A table that provides information for network hardware (bridges and routers) for them to forward data packets to other networks. The information contained in a routing table differs according to whether it is used by a bridge or a router. A bridge relies on both the source (originating) and destination addresses to determine where and how to forward a packet.
frame delay variation (FDV)
A measurement of the variations in the frame delay between a pair of service frames, where the service frames belong to the same CoS instance on a point to point ETH connection.
frame loss ratio (FLR)
A ratio, is expressed as a percentage, of the number of service frames not delivered divided by the total number of service frames during time interval T, where the number of service frames not delivered is the difference between the number of service frames arriving at the ingress ETH flow point and the number of service frames delivered at the egress ETH flow point in a point-to-point ETH connection.
frame relay (FR)
A packet-switching protocol used for WANs. Frame relay transmits variable-length packets at up to 2 Mbit/s over predetermined, set paths known as PVCs (permanent virtual circuits). It is a variant of X.25 but sacrifices X.25's error detection for the sake of speed.
frequency division duplex (FDD)
An application in which channels are divided by frequency. In an FDD system, the uplink and downlink use different frequencies. Downlink data is sent through bursts. Both uplink and downlink transmission use frames with fixed time length.
A safety device that protects an electric circuit from excessive current, consisting of or containing a metal element that melts when current exceeds a specific amperage, thereby opening the circuit.
generic associated channel header
Audio codec standard (A-law or U-law) that uses pulse code modulation (PCM). Its data rate is 64 kbit/s.
generic associated channel header label
general communication channel
GMPLS control plan
generic cell rate algorithm
Gigabit Ethernet
generic flow control
See Generic Framing Procedure.
generalized multiprotocol label switching
See gateway network element.
gigabit-capable passive optical network
See Global Positioning System.
See graceful restart.
See Generic Routing Encapsulation.
See global system for mobile communications.
graphical user interface
Generic Framing Procedure (GFP)
A framing and encapsulated method that can be applied to any data type. GFP is defined by ITU-T G.7041.
Generic Routing Encapsulation (GRE)
A mechanism for encapsulating any network layer protocol over any other network. GRE is used for encapsulating IP datagrams tunneled through the Internet. GRE serves as a Layer 3 tunneling protocol and provides a tunnel for transparently transmitting data packets.
Global Positioning System (GPS)
A global navigation satellite system that provides reliable positioning, navigation, and timing services to users worldwide.
The difference between the optical power from the input optical interface of the optical amplifier and the optical power from the output optical interface of the jumper fiber, which expressed in dB.
gateway network element (GNE)
An NE that serves as a gateway for other NEs to communicate with a network management system.
global system for mobile communications (GSM)
The second-generation mobile networking standard defined by the European Telecommunications Standards Institute (ETSI). It is aimed at designing a standard for global mobile phone networks. GSM consists of three main parts: mobile switching subsystem (MSS), base station subsystem (BSS), and mobile station (MS).
graceful restart (GR)
In IETF, protocols related to Internet Protocol/Multiprotocol Label Switching (IP/MPLS) such as Open Shortest Path First (OSPF), Intermediate System-Intermediate System (IS-IS), Border Gateway Protocol (BGP), Label Distribution Protocol (LDP), and Resource Reservation Protocol (RSVP) are extended to ensure that the forwarding is not interrupted when the system is restarted. This reduces the flapping of the protocols at the control plane when the system performs an active/standby switchover. This series of standards is called graceful restart.
higher order connection supervision
high definition serial digital interface
See High Density Bipolar of Order 3.
See high-definition television.
See header error control.
higher order path adaptation
higher order path termination
See hierarchical quality of service.
See High Speed Downlink Packet Access.
high-speed Internet
HUAWEI Electronic Document Explorer (HedEx)
The software used to view, search for, and upgrade electronic documentation of Huawei products. HedEx, pronounced as [hediks], has two editions, HedEx Lite and HedEx Server.
See HUAWEI Electronic Document Explorer.
High Density Bipolar of Order 3 (HDB3)
A code used for baseband transmissions between telecommunications devices. The HDB3 code has the following feature: high capability of clock extraction, no direct current component, error-checking capability, and a maximum of three consecutive zeros.
High Speed Downlink Packet Access (HSDPA)
A modulating-demodulating algorithm put forward in 3GPP R5 to meet the requirement for asymmetric uplink and downlink transmission of data services. It enables the maximum downlink data service rate to reach 14.4 Mbit/s without changing the WCDMA network topology.
header error control (HEC)
A field within the ATM frame whose purpose is to correct any single bit error in the cell Header and also to detect any multi-bit errors. It actually performs a CRC check in the first four header bits and also at the receiving end.
hierarchical quality of service (HQoS)
A type of QoS that controls the traffic of users and performs the scheduling according to the priority of user services. HQoS has an advanced traffic statistics function, and the administrator can monitor the usage of bandwidth of each service. Hence, the bandwidth can be allocated reasonably through traffic analysis.
high-definition television (HDTV)
High-definition television (HDTV) is a television system providing an image resolution that is substantially higher than that of standard-definition television.HDTV may be transmitted in various formats:1080p: 1920×1080p: 2,073,600 pixels (~2.07 megapixels) per frame1080i: 1920×1080i: 1,036,800 pixels (~1.04 MP) per field or 2,073,600 pixels (~2.07 MP) per frame Some countries also use a non-standard CEA resolution, such as 1440×1080i: 777,600 pixels (~0.78 MP) per field or 1,555,200 pixels (~1.56 MP) per frame720p: 1280×720p: 921,600 pixels (~0.92 MP) per frameThe letter "p" here stands for progressive scan, while "i" indicates interlaced.
incoming alignment error
See Internet Assigned Numbers Authority.
See integrated circuit.
See ITU carrier code.
See Internet Control Message Protocol.
IMA Control Protocol
See indoor unit.
International Electrotechnical Commission
See Institute of Electrical and Electronics Engineers.
Internet Engineering Task Force
See Internet Group Management Protocol.
See Interior Gateway Protocol.
incoming label map
IMA frame
A control unit in the IMA protocol. It is a logical frame defined as M consecutive cells, numbered 0 to M-l, transmitted on each of the N links in an IMA group.
Internet Protocol
See intelligent power adjustment.
See Internet Protocol television.
See Internet Protocol version 4.
See Internet Protocol version 6.
Integrated Services Digital Network
See Internet service provider.
internal spanning tree
independent transmit clock
See International Telecommunication Union.
ITU carrier code (ICC)
A code assigned to a network operator/service provider, maintained by the ITU-T Telecommunication Standardization Bureau (TSB).
International Telecommunication Union-Telecommunication Standardization Sector
Institute of Electrical and Electronics Engineers (IEEE)
A professional association of electrical and electronics engineers based in the United States, but with membership from numerous other countries. The IEEE focuses on electrical, electronics, and computer engineering, and produces many important technology standards.
Interior Gateway Protocol (IGP)
A routing protocol that is used within an autonomous system. The IGP runs in small-sized and medium-sized networks. The IGPs are RIP, IGRP, EIGRP, OSPF, and IS-IS.
International Telecommunication Union (ITU)
A United Nations agency, one of the most important and influential recommendation bodies, responsible for recommending standards for telecommunication (ITU-T) and radio networks (ITU-R).
Internet Assigned Numbers Authority (IANA)
A department operated by the IAB. IANA delegates authority for IP address-space allocation and domain-name assignment to the NIC and other organizations. IANA also maintains a database of assigned protocol identifiers used in the TCP/IP suite, including autonomous system numbers.
Internet Control Message Protocol (ICMP)
A network layer protocol that provides message control and error reporting between a host server and an Internet gateway.
Internet Group Management Protocol (IGMP)
One of the TCP/IP protocols for managing the membership of Internet Protocol multicast groups. It is used by IP hosts and adjacent multicast routers to establish and maintain multicast group memberships.
Internet Protocol television (IPTV)
A system that provides TV services over the IP network. In the IPTV system, media streams from satellites, terrestrial, and studios are converted by the encoder to the media streams applicable to the IP network. Then the media streams are transmitted to the terminal layer on the IP network. Media content is displayed on a TV set after media streams are processed by specified receiving devices (for example, an STB).
Internet Protocol version 4 (IPv4)
The current version of the Internet Protocol (IP). IPv4 utilizes a 32bit address which is assigned to hosts. An address belongs to one of five classes (A, B, C, D, or E) and is written as 4 octets separated by periods and may range from through to Each IPv4 address consists of a network number, an optional subnetwork number, and a host number. The network and subnetwork numbers together are used for routing, and the host number is used to address an individual host within the network or subnetwork.
Internet Protocol version 6 (IPv6)
An update version of IPv4, which is designed by the Internet Engineering Task Force (IETF) and is also called IP Next Generation (IPng). It is a new version of the Internet Protocol. The difference between IPv6 and IPv4 is that an IPv4 address has 32 bits while an IPv6 address has 128 bits.
Internet service provider (ISP)
An organization that offers users access to the Internet and related services.
indoor unit (IDU)
The indoor unit of the split-structured radio equipment. It implements accessing, multiplexing/demultiplexing, and intermediate frequency (IF) processing for services.
integrated circuit (IC)
A combination of inseparable associated circuit elements that are formed in place and interconnected on or within a single base material to perform a microcircuit function.
intelligent power adjustment (IPA)
A technology that reduces the optical power of all the amplifiers in an adjacent regeneration section in the upstream to a safe level if the system detects the loss of optical signals on the link. IPA helps ensure that maintenance engineers are not injured by the laser escaping from a broken fiber or a connector that is not plugged in properly.
The measure of short waveform variations caused by vibration, voltage fluctuations, and control system instability.
A connection wire for connecting two pins.
Layer 2 virtual private network
Layer 3 virtual private network
See Link Aggregation Control Protocol.
Link Aggregation Control Protocol data unit
See link aggregation group.
See local area network.
link access procedure on the D channel
Link Access Protocol-SDH
See loopback.
See loopback message.
See loopback reply.
Lucent connector
See link capacity adjustment scheme.
liquid crystal display
See Locked signal function.
local communication network
local craft terminal
See label edge router.
See last in first out.
logical interface unit
See logical link control.
local loopback ID
See loss measurement.
link management protocol
loss of continuity
loss of multiframe
loss of pointer
See loss of signal.
lower order path
lower order path adaptation
link-state pass through
link-state advertisement
See label switching router.
Long Term Evolution
See linktrace message.
See linktrace reply.
line unit
See low voltage differential signal.
Layer 2 switching
A data forwarding method. In a LAN, a network bridge or 802.3 Ethernet switch transmits and distributes packet data based on the MAC address. Since the MAC address is at the second layer of the OSI model, this data forwarding method is called Layer 2 switching.
Link Aggregation Control Protocol (LACP)
A dynamic link aggregation protocol that improves the transmission speed and reliability. The two ends of the link send LACP packets to inform each other of their parameters and form a logical aggregation link. After the aggregation link is formed, LACP maintains the link status in real time and dynamically adjusts the ports on the aggregation link upon detecting the failure of a physical port.
Locked signal function (LCK)
A function administratively locks an MEG end point (MEP) at the server layer, informs consequential data traffic interruption to the peer MEP at the client layer, and suppresses the alarm at the client layer.
label edge router (LER)
A device that sits at the edge of an MPLS domain, that uses routing information to assign labels to datagrams and then forwards them into the MPLS domain.
label switching router (LSR)
Basic element of an MPLS network. All LSRs support the MPLS protocol. The LSR is composed of two parts: control unit and forwarding unit. The former is responsible for allocating the label, selecting the route, creating the label forwarding table, creating and removing the label switch path; the latter forwards the labels according to groups received in the label forwarding table.
last in first out (LIFO)
A play mode of the voice mails, the last voice mail is played firstly.
link aggregation group (LAG)
An aggregation that allows one or more links to be aggregated together to form a link aggregation group so that a MAC client can treat the link aggregation group as if it were a single link.
link capacity adjustment scheme (LCAS)
LCAS in the virtual concatenation source and sink adaptation functions provides a control mechanism to hitless increase or decrease the capacity of a link to meet the bandwidth needs of the application. It also provides a means of removing member links that have experienced failure. The LCAS assumes that in cases of capacity initiation, increases or decreases, the construction or destruction of the end-to-end path is the responsibility of the network and element management systems.
linktrace message (LTM)
The message sent by the initiator MEP of 802.1ag MAC Trace to the destination MEP. LTM includes the Time to Live (TTL) and the MAC address of the destination MEP2.
linktrace reply (LTR)
For 802.1ag MAC Trace, the destination MEP replies with a response message to the source MEP after the destination MEP receives the LTM, and the response message is called LTR. LTR also includes the TTL that equals the result of the TTL of LTM minus 1.
local area network (LAN)
A network formed by the computers and workstations within the coverage of a few square kilometers or within a single building, featuring high speed and low error rate. Current LANs are generally based on switched Ethernet or Wi-Fi technology and run at 1,000 Mbit/s (that is, 1 Gbit/s).
logical link control (LLC)
According to the IEEE 802 family of standards, Logical Link Control (LLC) is the upper sublayer of the OSI data link layer. The LLC is the same for the various physical media (such as Ethernet, token ring, WLAN).
loopback (LB)
A troubleshooting technique that returns a transmitted signal to its source so that the signal or message can be analyzed for errors. The loopback can be a inloop or outloop.
loopback message (LBM)
The loopback packet sent by the node that supports 802.2ag MAC Ping to the destination node. LBM message carries its own sending time.
loopback reply (LBR)
A response message involved in the 802.1ag MAC Ping function, with which the destination MEP replies to the source MEP after the destination MEP receives the LBM. The LBR carries the sending time of LBM, the receiving time of LBM and the sending time of LBR.
loss measurement (LM)
A method used to collect counter values applicable for ingress and egress service frames where the counters maintain a count of transmitted and received data frames between a pair of MEPs.
loss of signal (LOS)
No transitions occurring in the received signal.
low voltage differential signal (LVDS)
A low noise, low power, low amplitude method for high-speed (gigabits per second) data transmission over copper wire.
maintenance association
See Media Access Control.
multiple add/drop multiplexer
mobile broadband
maximum burst size
message communication function
minimum cell rate
See maintenance domain.
See message digest algorithm 5.
See main distribution frame.
See maintenance entity.
See maintenance entity group.
maintenance entity group level
maintenance association end point
See multiframe alignment signal.
See management information base.
maintenance association intermediate point
See multicast listener discovery.
mechanized loop testing
maintenance point
See MPEG audio layer-3.
MPEG audio layer-3 (MP3)
A digital audio coding scheme used in distributing recorded music over the Internet. MP3 shrinks the size of an audio file by a factor of 10 to 12 without seriously degrading the quality (CD-recording level) of the sound.
maintenance point identification
See Multiprotocol Label Switching.
multiprotocol label switching traffic engineering
See Multiprotocol Label Switching traffic policing.
See multiprotocol label switching virtual private network.
MPLS-TP shared protection ring (SPRing)
A protection switchover mechanism defined in the ITU-T G.8132 standard. A group of nodes constitute a closed loop and each node is connected to two adjacent nodes using a bidirectional channel. Ring network protection involves two rings that provide protection for each other and are in opposite directions. Both of the two rings provide working and protection channels and redundant bandwidth or network devices. In this way, services can be automatically restored after the network does not function properly or deteriorates.
multiplex section
See multiplex section alarm indication signal.
See multi-segment pseudo wire.
multiplex section adaptation
multiplex section overhead
See multiplex section protection.
See multiplex section termination.
MST region
See Multiple Spanning Tree region.
See multiple spanning tree instance.
See Multiple Spanning Tree Protocol.
See Mean Time Between Failures.
See Mean Time to Repair.
See maximum transmission unit.
See multiplexer.
Mean Time Between Failures (MTBF)
The average time between consecutive failures of a piece of equipment. It is a measure of the reliability of the system.
Mean Time to Repair (MTTR)
The average time that a device will take to recover from a failure.
Media Access Control (MAC)
A protocol at the media access control sublayer. The protocol is at the lower part of the data link layer in the OSI model and is mainly responsible for controlling and connecting the physical media at the physical layer. When transmitting data, the MAC protocol checks whether to be able to transmit data. If the data can be transmitted, certain control information is added to the data, and then the data and the control information are transmitted in a specified format to the physical layer. When receiving data, the MAC protocol checks whether the information is correct and whether the data is transmitted correctly. If the information is correct and the data is transmitted correctly, the control information is removed from the data and then the data is transmitted to the LLC layer.
Multiple Spanning Tree Protocol (MSTP)
A protocol that can be used in a loop network. Using an algorithm, the MSTP blocks redundant paths so that the loop network can be trimmed as a tree network. In this case, the proliferation and endless cycling of packets is avoided in the loop network. The protocol that introduces the mapping between VLANs and multiple spanning trees. This solves the problem that data cannot be normally forwarded in a VLAN because in STP/RSTP, only one spanning tree corresponds to all the VLANs.
Multiple Spanning Tree region (MST region)
A region that consists of switches that support the MSTP in the LAN and links among them. Switches physically and directly connected and configured with the same MST region attributes belong to the same MST region.
Multiprotocol Label Switching (MPLS)
A technology that uses short tags of fixed length to encapsulate packets in different link layers, and provides connection-oriented switching for the network layer on the basis of IP routing and control protocols.
Multiprotocol Label Switching traffic policing (MPLS TP)
It is a scheme that supervises the specific traffic entering the communication devices. By policing the speed of traffic that enters the network, it "punishes" the traffic out of the threshold, so the traffic going into network is limited to a reasonable range, protecting the network resources and the interests of the carriers.
main distribution frame (MDF)
A device at a central office, on which all local loops are terminated.
maintenance domain (MD)
The network or the part of the network for which connectivity is managed by connectivity fault management (CFM). The devices in a maintenance domain are managed by a single Internet service provider (ISP).
maintenance entity (ME)
An ME consists of a pair of maintenance entity group end points (MEPs), two ends of a transport trail, and maintenance association intermediate points (MIPs) on the trail.
maintenance entity group (MEG)
A MEG consists of MEs that meet the following criteria:1. Exist within the same management edges.2. Have the same MEG hierarchy.3. Belong to the same P2P or P2MP connection.
management information base (MIB)
A type of database used for managing the devices in a communications network. It comprises a collection of objects in a (virtual) database used to manage entities (such as routers and switches) in a network.
manual switching
The action of manually switching traffic signals between a working channel and a protection channel. Manual switching fails if the channel to which traffic is being switched is faulty or an equal or higher priority switching command is in effect.
maximum transmission unit (MTU)
The largest packet of data that can be transmitted on a network. MTU size varies, depending on the network-576 bytes on X.25 networks, for example, 1500 bytes on Ethernet, and 17,914 bytes on 16 Mbit/s token ring. Responsibility for determining the size of the MTU lies with the link layer of the network. When packets are transmitted across networks, the path MTU, or PMTU, represents the smallest packet size (the one that all networks can transmit without breaking up the packet) among the networks involved.
message digest algorithm 5 (MD5)
A hash function that is used in a variety of security applications to check message integrity. MD5 processes a variable-length message into a fixed-length output of 128 bits. It breaks up an input message into 512-bit blocks (sixteen 32-bit little-endian integers). After a series of processing, the output consists of four 32-bit words, which are then cascaded into a 128-bit hash number.
The duplication of data for backup or to distribute network traffic among several computers with identical data.
multi-segment pseudo wire (MS-PW)
A collection of multiple adjacent PW segments. Each PW segment is a point-to-point PW. The use of MS-PWs to bear services saves tunnel resources and can transport services over different networks.
A process of transmitting data packets from one source to many destinations. The destination address of the multicast packet uses Class D address, that is, the IP address ranges from to Each multicast address represents a multicast group rather than a host.
multicast listener discovery (MLD)
A protocol used by an IPv6 router to discover the multicast listeners on their directly connected network segments, and to set up and maintain member relationships. On IPv6 networks, after MLD is configured on the receiver hosts and the multicast router to which the hosts are directly connected, the hosts can dynamically join related groups and the multicast router can manage members on the local network.
multiframe alignment signal (MFAS)
A distinctive signal inserted into every multiframe or once into every n multiframes, always occupying the same relative position within the multiframe, and used to establish and maintain multiframe alignment.
multiple spanning tree instance (MSTI)
A type of spanning trees calculated by MSTP within an MST Region, to provide a simply and fully connected active topology for frames classified as belonging to a VLAN that is mapped to the MSTI by the MST Configuration. A VLAN cannot be assigned to multiple MSTIs.
multiplex section alarm indication signal (MS-AIS)
An all-ONES characteristic or adapted information signal. It's generated to replace the normal traffic signal when it signal contains a defect condition in order to prevent consequential downstream failures being declared or alarms being raised. AIS can be identified as multiplex section alarm indication signal.
multiplex section protection (MSP)
A function, which is performed to provide capability for switching a signal between and including two multiplex section termination (MST) functions, from a "working" to a "protection" channel.
multiplex section termination (MST)
A function that generates the multiplex section overhead (MSOH) during the formation of an SDH frame signal and that terminates the MSOH in the reverse direction.
multiplexer (MUX)
Equipment that combines a number of tributary channels onto a fewer number of aggregate bearer channels, the relationship between the tributary and aggregate channels being fixed.
A procedure by which multiple lower order path layer signals are adapted into a higher order path or the multiple higher order path layer signals are adapted into a multiplex section.
multiprotocol label switching virtual private network (MPLS VPN)
An Internet Protocol (IP) virtual private network (VPN) based on the multiprotocol label switching (MPLS) technology. It applies the MPLS technology for network routers and switches, simplifies the routing mode of core routers, and combines traditional routing technology and label switching technology. It can be used to construct the broadband Intranet and Extranet to meet various service requirements.
network access server
new data flag
network element
Network Equipment Building System
next hop label forwarding entry
normal link pulse
network maintenance interface
network-to-network interface
See network parameter control.
network provider edge
non-real-time variable bit rate
non-return to zero
NRZ code
non-return-to-zero code
non-return to zero inverted
See network service access point.
non-stop forwarding
Network Time Protocol
nonvolatile random access memory
network parameter control (NPC)
During communications, UPC is implemented to monitor the actual traffic on each virtual circuit that is input to the network. Once the specified parameter is exceeded, measures will be taken to control. NPC is similar to UPC in function. The difference is that the incoming traffic monitoring function is divided into UPC and NPC according to their positions. UPC locates at the user/network interface, while NPC at the network interface.
network segment
Part of a network on which all message traffic is common to all nodes; that is, a message broadcast from one node on the segment is received by all other nodes on the segment.
network service access point (NSAP)
A network address defined by ISO, at which the OSI Network Service is made available to a Network service user by the Network service provider.
noise figure
A measure of degradation of the signal-to-noise ratio (SNR), caused by components in a radio frequency (RF) signal chain. The noise figure is defined as the ratio of the output noise power of a device to the portion thereof attributable to thermal noise in the input termination at standard noise temperature T0 (usually 290 K). The noise figure is thus the ratio of actual output noise to that which would remain if the device itself did not introduce noise. It is a number by which the performance of a radio receiver can be specified.
See non-gateway network element.
non-gateway network element (non-GNE)
A network element that communicates with the NM application layer through the gateway NE application layer.
operation and maintenance
optical amplifier
See optical add/drop multiplexer.
See operation, administration and maintenance.
operation, administration, maintenance and provision
operation, administration and maintenance protocol data unit
Optical fiber line Automatic Monitoring System
See optical amplifier unit.
ordinary clock
optical core switching
optical channel with full functionality
optical distribution frame
See outdoor unit.
optical channel data unit - k
overhead processing
See optical network terminal.
See optical network unit.
out of frame
out of service
operating expense
optical physical section
See optical channel payload unit.
optical channel payload unit - k
See optical supervisory channel.
open systems interconnection
optical switch node
See optical signal-to-noise ratio.
See Open Shortest Path First.
Open Shortest Path First-Traffic Engineering
See optical time domain reflectometer.
optical transport network
See optical transmission section.
See optical transponder unit.
optical channel transport unit - k
Open Shortest Path First (OSPF)
A link-state, hierarchical interior gateway protocol (IGP) for network routing that uses cost as its routing metric. A link state database is constructed of the network topology, which is identical on all routers in the area.
Defines the start position of the data part to be inspected in a packet or a stream. The value of the offset cannot be greater than the maximum stream length. Packet offset applies to every packet in every stream; stream offset applies to the first packet of every stream.
operation, administration and maintenance (OAM)
A set of network management functions that cover fault detection, notification, location, and repair.
optical add/drop multiplexer (OADM)
A device that can be used to add the optical signals of various wavelengths to one channel and drop the optical signals of various wavelengths from one channel.
optical amplifier unit (OAU)
A board that is mainly responsible for amplifying optical signals. The OAU can be used in both the transmitting direction and the receiving direction.
optical attenuator
A passive device that increases the attenuation in a fiber link. An optical attenuator is used to ensure that the optical power of a signal at the receive end is not excessively high.
optical channel payload unit (OPU)
A protection architecture that allows one wavelength to provide protection for multiple services between different stations, saving wavelength resources and lowering costs.
optical network terminal (ONT)
A device that terminates the fiber optical network at the customer premises.
optical network unit (ONU)
A form of Access Node that converts optical signals transmitted via fiber to electrical signals that can be transmitted via coaxial cable or twisted pair copper wiring to individual subscribers.
optical signal-to-noise ratio (OSNR)
The ratio of signal power to noise power in a transmission link. OSNR is the most important index for measuring the performance of a DWDM system.
optical supervisory channel (OSC)
A technology that uses specific optical wavelengths to realize communication among nodes in optical transmission network and transmit the monitoring data in a certain channel.
optical time domain reflectometer (OTDR)
A device that sends a series of short pulses of light down a fiber-optic cable and measures the strength of the return pulses. An OTDR is used to measure fiber length and light loss, and to locate fiber faults.
optical transmission section (OTS)
A section in the logical structure of an optical transport network (OTN). The OTS allows the network operator to perform monitoring and maintenance tasks between NEs.
optical transponder unit (OTU)
A device or subsystem that converts accessed client signals into a G.694.1/G.694.2-compliant WDM wavelength.
A channel that provides voice communication between operation engineers or maintenance engineers of different stations.
outdoor unit (ODU)
The outdoor unit of the split-structured radio equipment. It implements frequency conversion and amplification for radio frequency (RF) signals.
See point-to-point service.
power amplifier
PPPoE active discovery request
private branch exchange
personal computer
See printed circuit board.
See peripheral component interconnect.
See pulse code modulation.
product change notice
See peak cell rate.
See plesiochronous digital hierarchy.
See power distribution unit.
See provider edge.
PGND cable
A cable which connects the equipment and the protection grounding bar. Usually, one half of the cable is yellow, whereas the other half is green.
See per-hop behavior.
penultimate hop popping
Protocol Independent Multicast - Dense Mode
Protocol Independent Multicast - Sparse Mode
See phase-locked loop.
performance monitoring
polarization mode dispersion
power monitoring unit
private network-node interface
passive optical network
See packet over SDH/SONET.
See plain old telephone service.
partial packet discard
PDH physical interface
Point-to-Point Protocol
Point-to-Point Protocol over Ethernet
port protection switching
See priority queuing.
See pseudo random binary sequence.
primary reference clock
payload structure identifier
See packet switched network.
See public switched telephone network.
See power supply unit.
payload type
payload type indicator
packet transport network
Precision Time Protocol
See permanent virtual circuit.
See port VLAN ID.
See permanent virtual path.
See pseudo wire.
See pseudo wire emulation edge-to-edge.
Power Cable
See plug-and-play.
packet discarding
A function of discarding the packets from unknown VLAN domain or broadcast packets. Packet Discarding is used to prevent the situation where unknown packets or broadcast packets use the bandwidth on a link, improving the reliability of service transmission.
packet loss
The discarding of data packets in a network when a device is overloaded and cannot accept any incoming data at a given moment.
packet over SDH/SONET (POS)
A MAN and WAN technology that provides point-to-point data connections. The POS interface uses SDH/SONET as the physical layer protocol, and supports the transport of packet data (such as IP packets) in MAN and WAN.
packet per second (pps)
Packet per second though the network card. Unit of data service bandwidth.
packet switched network (PSN)
A telecommunications network that works in packet switching mode.
parity check
A method for character level error detection. An extra bit is added to a string of bits, usually a 7-bit ASCII character, so that the total number of bits 1 is odd or even (odd or even parity). Both ends of a data transmission must use the same parity. When the transmitting device frames a character, it counts the numbers of 1s in the frame and attaches the appropriate parity bit. The recipient counts the 1s and, if there is parity error, may ask for the data to be retransmitted.
peak cell rate (PCR)
The maximum rate at which an ATM connection can accept cells.
per-hop behavior (PHB)
IETF Diff-Serv workgroup defines forwarding behaviors of network nodes as per-hop behaviors (PHB), such as, traffic scheduling and policing. A device in the network should select the proper PHB behaviors, based on the value of DSCP. At present, the IETF defines four types of PHB. They are class selector (CS), expedited forwarding (EF), assured forwarding (AF), and best-effort (BE).
performance threshold
A limit for generating an alarm for a selected entity. When the measurement result reaches or exceeds the preset alarm threshold, the performance management system generates a performance alarm.
peripheral component interconnect (PCI)
A standard designed for the bus connecting the computer main board to peripheral devices. The PCI1.0 standard was released by Intel in 1992 and related standards have been released by PCI-SIG since 1993. Peripheral component interconnect (PCI) delivers I/O functionality for computers ranging from servers to workstations, PCs, laptop PCs and mobile devices.
permanent virtual circuit (PVC)
A circuit that can be established as an option to provide a dedicated circuit link between two facilities. PVC configuration is usually preconfigured by the service provider. Unlike SVCs, PVCs are usually very seldom broken/disconnected. A permanent virtual circuit (PVC) is a virtual circuit established for repeated/continuous use between the same DTE. In a PVC, the long-term association is identical to the data transfer phase of a virtual call. Permanent virtual circuits eliminate the need for repeated call set-up and clearing.
permanent virtual path (PVP)
Virtual path that consists of PVCs.
phase-locked loop (PLL)
A circuit that consists essentially of a phase detector that compares the frequency of a voltage-controlled oscillator with that of an incoming carrier signal or reference-frequency generator. The output of the phase detector, after passing through a loop filter, is fed back to the voltage-controlled oscillator to keep it exactly in phase with the incoming or reference frequency.
ping test
A test that is performed to send a data packet to the target IP address (a unique IP address on the device on the network) to check whether the target host exists according to the data packet of the same size returned from the target host.
plain old telephone service (POTS)
The basic telephone service provided through the traditional cabling such as twisted pair cables.
plesiochronous digital hierarchy (PDH)
A multiplexing scheme of bit stuffing and byte interleaving. It multiplexes the minimum rate 64 kit/s into rates of 2 Mbit/s, 34 Mbit/s, 140 Mbit/s, and 565 Mbit/s.
plug-and-play (PnP)
A Windows technology that automatically detects and configures most of the adapters and peripherals that can be connected to a PC. For communication networks, fast discovery of network topology can help the newly attached devices communicate with the nodes on the network, without the need to configure the new devices.
point-to-point service (P2P)
A service between two terminal users. In P2P services, senders and recipients are terminal users.
A default VLAN ID of a port. It is allocated to a data frame if the data frame carries no VLAN tag when reaching the port.
power distribution unit (PDU)
A unit that performs AC or DC power distribution.
power supply unit (PSU)
A unit that converts the external power input into the power supply for internal use. Power supply units are classified into AC power units and DC power units.
See packet per second.
printed circuit board (PCB)
A board used to mechanically support and electrically connect electronic components using conductive pathways, tracks, or traces, etched from copper sheets laminated onto a non-conductive substrate.
priority queuing (PQ)
A queue scheduling algorithm based on the absolute priority. According to the PQ algorithm, services of higher priorities are ensured with greater bandwidth, lower latency, and less jitter. Packets of lower priorities must wait to be sent till all packets of higher priorities are sent. In this manner, services of higher priorities are processed earlier than others.
provider edge (PE)
A device that is located in the backbone network of the MPLS VPN structure. A PE is responsible for managing VPN users, establishing LSPs between PEs, and exchanging routing information between sites of the same VPN. A PE performs the mapping and forwarding of packets between the private network and the public channel. A PE can be a UPE, an SPE, or an NPE.
pseudo random binary sequence (PRBS)
A sequence that is random in the sense that the value of each element is independent of the values of any of the other elements, similar to a real random sequence.
pseudo wire (PW)
An emulated connection between two PEs for transmitting frames. The PW is established and maintained by PEs through signaling protocols. The status information of a PW is maintained by the two end PEs of a PW.
pseudo wire emulation edge-to-edge (PWE3)
An end-to-end Layer 2 transmission technology. It emulates the essential attributes of a telecommunication service such as ATM, FR or Ethernet in a packet switched network (PSN). PWE3 also emulates the essential attributes of low speed time division multiplexing (TDM) circuit and SONET/SDH. The simulation approximates to the real situation.
public switched telephone network (PSTN)
A telecommunications network established to perform telephone services for the public subscribers. Sometimes it is called POTS.
pulse code modulation (PCM)
A method of encoding information in a signal by changing the amplitude of pulses. Unlike pulse amplitude modulation (PAM), in which pulse amplitude can change continuously, pulse code modulation limits pulse amplitudes to several predefined values. Because the signal is discrete, or digital, rather than analog, pulse code modulation is more immune to noise than PAM.
See quadrature phase shift keying.
See 802.1Q in 802.1Q.
quadrature phase shift keying (QPSK)
QPSK modulates two bits into each modulation symbol.
See Remote Authentication Dial In User Service.
remote alarm indication
See radio access network.
remote defect indication
See random early detection.
See regenerator.
remote error indication
See Requirement For Comments.
red green blue
See Routing Information Protocol.
registered jack
remote maintenance association end point
remote network monitoring
See radio network controller.
See remote optical pumping amplifier.
resilient packet ring
regenerator section
See Recommended Standard 232.
The specification that defines the electrical characteristics of balanced voltage digital interface circuits. The interface can change to RS232 via the hardware jumper and others are the same as RS232.
See received signal level.
regenerator section overhead
See received signal strength indicator.
regenerator section termination
See Rapid Spanning Tree Protocol.
See Resource Reservation Protocol.
See Resource Reservation Protocol-Traffic Engineering.
radio transmission node
request to send
See remote test unit.
Rapid Spanning Tree Protocol (RSTP)
An evolution of the Spanning Tree Protocol (STP) that provides faster spanning tree convergence after a topology change. The RSTP protocol is backward compatible with the STP protocol.
Recommended Standard 232 (RS232)
A standard that defines the electrical characteristics, timing, and meaning of signals, and the physical size and pinout of connectors.
Remote Authentication Dial In User Service (RADIUS)
A security service that authenticates and authorizes dial-up users and is a centralized access control mechanism. As a distributed server/client system, RADIUS provides the AAA function.
Requirement For Comments (RFC)
A document about standards, protocols, or other information pertaining to the operation of the Internet. The RFC, under the control of the Internet Architecture Board (IAB), is actually issued after discussion and serves as a standard document. RFCs can be obtained from sources such as InterNIC.
Resource Reservation Protocol (RSVP)
A protocol that reserves resources on every node along a path. RSVP is designed for an integrated services Internet.
Resource Reservation Protocol-Traffic Engineering (RSVP-TE)
An extension to the RSVP protocol for setting up label switched paths (LSPs) in MPLS networks. The RSVP-TE protocol is used to establish and maintain the LSPs by initiating label requests and allocating label binding messages. It also supports LSP rerouting and LSP bandwidth increasing.
restriction of the use of certain hazardous substances
Routing Information Protocol (RIP)
A simple routing protocol that is part of the TCP/IP protocol suite. It determines a route based on the smallest hop count between the source and destination. RIP is a distance vector protocol that routinely broadcasts routing information to its neighboring routers and is known to waste bandwidth.
radio access network (RAN)
The network that provides the connection between CPEs and the CN. It isolates the CN from wireless network.
radio network controller (RNC)
A device in a radio network subsystem that is in charge of controlling the usage and integrity of radio resources.
random early detection (RED)
A packet loss algorithm used in congestion avoidance. It discards the packet according to the specified higher limit and lower limit of a queue so that global TCP synchronization resulting from traditional tail drop can be prevented.
real-time variable bit rate (rt-VBR)
A parameter intended for real-time applications, such as compressed voice over IP (VoIP) and video conferencing. The rt-VBR is characterized by a peak cell rate (PCR), sustained cell rate (SCR), and maximum burst size (MBS). You can expect the source device to transmit in bursts and at a rate that varies with time.
received signal level (RSL)
The signal level at a receiver input terminal.
received signal strength indicator (RSSI)
The received wide band power, including thermal noise and noise generated in the receiver, within the bandwidth defined by the receiver pulse shaping filter, for TDD within a specified timeslot. The reference point for the measurement shall be the antenna. This is a value reported for the strength of a frame that has been received; it acts much like a "volume" indicator for the transmission. The RSSI may be reported in many different ways, but a common method is in dBm.
reference clock
A stable and high-precision autonomous clock that provides frequencies as a reference for other clocks.
regenerator (REG)
A piece of equipment or device that regenerates electrical signals.
remote optical pumping amplifier (ROPA)
A remote optical amplifier subsystem designed for applications where power supply and monitoring systems are unavailable. The ROPA subsystem is a power compensation solution to the ultra-long distance long hop (LHP) transmission.
remote test unit (RTU)
A subsystem capable of collecting, pre-processing, and sending data coming from the field sensors to the SCU.
See real-time variable bit rate.
service virtual local area network
service area identifier
See storage area network.
source access point identifier
Structure-Agnostic Time Division Multiplexing over Packet
square connector
sustainable cell rate
See signal degrade.
See standard definition-serial digital interface signal.
See synchronous digital hierarchy.
See serial digital interface.
serious disturbance period
security screening
See single-ended loop test.
safety extra-low voltage
synchronous equipment management function
severely errored second
SDH equipment timing source
See signal fail.
small form-factor pluggable
See Secure File Transfer Protocol.
See single-pair high-speed digital subscriber line.
See Service Level Agreement.
See Serial Line Interface Protocol.
single longitudinal mode
section monitoring
sub-miniature B
See single-mode fiber.
side mode suppression ratio
subnetwork connection
subnetwork connection multipath protection
subnetwork connection protection
subnetwork connection tunnel protection
See simple network management protocol.
section overhead
See synchronous optical network.
soft permanent connection
SDH physical interface
See MPLS-TP shared protection ring.
See shared risk group.
shared risk link group
See Secure Shell.
See Secure Sockets Layer.
See Synchronization Status Message.
synchronization status message byte
synchronization source
synchronization supply unit
system target decoder
See synchronous transport module.
Synchronous Transport Module level N
Spanning Tree Protocol
Secure Shell Telnet
switched virtual connection
Secure File Transfer Protocol (SFTP)
A network protocol designed to provide secure file transfer over SSH.
Secure Shell (SSH)
SSH is a set of network protocols for securing connections between computers, as well as the utility suite that implements these protocols.
Secure Sockets Layer (SSL)
A security protocol that works at a socket layer. This layer exists between the TCP layer and the application layer to encrypt/decode data and authenticate concerned entities.
Serial Line Interface Protocol (SLIP)
A protocol that defines the framing mode over the serial line to implement transmission of messages over the serial line and provide the remote host interconnection function with a known IP address.
Service Level Agreement (SLA)
A service contract between a customer and a (SLA) service provider that specifies the forwarding service a customer should receive. A customer may be a user organization (source domain) or another DS domain (upstream domain). A SLA may include traffic conditioning rules which constitute a TCA in whole or in part.
Synchronization Status Message (SSM)
A message that carries the quality levels of timing signals on a synchronous timing link. SSM messages provide upstream clock information to nodes on an SDH network or synchronization network.
serial digital interface (SDI)
An interface that transmits data in a single channel in sequence.
shared risk group (SRG)
A group of resources that share a common risk component whose failure can cause the failure of all the resources in the group.
signal degrade (SD)
A signal indicating that associated data has degraded in the sense that a degraded defect condition is active.
signal fail (SF)
A signal indicating that associated data has failed in the sense that a near-end defect condition (non-degrade defect) is active.
simple network management protocol (SNMP)
An IETF protocol for monitoring and managing systems and devices in a network.The data being monitored and managed is defined by a MIB. The functions supported by the protocol are the request and retrieval of data, the setting or writing of data, and traps that signal the occurrence of events.
single-ended loop test (SELT)
An automated way of testing a DSL loop from one end of the line, providing operators with a method for efficiently evaluating their loop as part of their daily operational practices.
single-mode fiber (SMF)
A type of optical fiber through which only one type of optical signal with a fixed wave length can travel at a time. The inner diameter of the single-mode fiber is less than 10 microns. This type of fiber can transmit data over a long distance.
single-pair high-speed digital subscriber line (SHDSL)
A symmetric digital subscriber line technology developed from HDSL, SDSL, and HDSL2, which is defined in ITU-T G.991.2. The SHDSL port is connected to the user terminal through the plain telephone subscriber line and uses trellis coded pulse amplitude modulation (TC-PAM) technology to transmit high-speed data and provide the broadband access service.
The physical reach between two pieces of WDM equipment.
standard definition-serial digital interface signal (SD-SDI)
Standard definition video signal transported by serial digital interface.
A protection switching mode defined in ITU-T G.8132, which is applicable to packet-based T-MPLS ring networks and similar to SDH transoceanic multiplex section protection (MSP). In this mode, the switching is triggered by the source and sink nodes of a service.
storage area network (SAN)
A storage area network (SAN) is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage devices, such as disk arrays, tape libraries, and optical jukeboxes, accessible to servers so that the devices appear like locally attached devices to the operating system.A SAN does not provide file abstraction, only block-level operations. However, file systems built on top of SANs do provide file-level access, and are known as SAN filesystems or shared disk file systems. An architecture to attach remote computer storage devices such as disk array controllers, tape libraries and CD arrays to servers in such a way that to the operating system the devices appear as locally attached devices.An architecture to attach remote computer storage devices such as disk array controllers, tape libraries and CD arrays to servers in such a way that to the operating system the devices appear as locally attached devices.
synchronous digital hierarchy (SDH)
A transmission scheme that follows ITU-T G.707, G.708, and G.709. SDH defines the transmission features of digital signals, such as frame structure, multiplexing mode, transmission rate level, and interface code. SDH is an important part of ISDN and B-ISDN.
synchronous optical network (SONET)
A high-speed network that provides a standard interface for communications carriers to connect networks based on fiber optical cable. SONET is designed to handle multiple data types (voice, video, and so on). It transmits at a base rate of 51.84 Mbit/s, but multiples of this base rate go as high as 2.488 Gbit/s.
synchronous transport module (STM)
An information structure used to support section layer connections in the SDH. It consists of information payload and Section Overhead (SOH) information fields organized in a block frame structure which repeats every 125. The information is suitably conditioned for serial transmission on the selected media at a rate which is synchronized to the network. A basic STM is defined at 155 520 kbit/s. This is termed STM-1. Higher capacity STMs are formed at rates equivalent to N times this basic rate. STM capacities for N = 4, N = 16 and N = 64 are defined; higher values are under consideration.
tracking area identity
transmission convergence
tag control information
tandem connection monitor
telecommunication network
See Transmission Control Protocol.
Transmission Control Protocol/Internet Protocol
transmit degrade
See Time Division-Synchronous Code Division Multiple Access.
tunable dispersion compensator
time division duplex
See time division multiplexing.
See Trivial File Transfer Protocol.
trail trace identifier mismatch
Transaction Language 1
Transport Layer Security
See type-length-value.
See terminal multiplexer.
See telecommunications management network.
time of day
type of service
tag protocol identifier
See tributary protection switching.
trail signal degrade
See Test.
trail trace identifier
See time to live.
See trail termination source identifier.
tributary unit
tributary unit group
Test (TST)
A function which is used to perform one-way on-demand in-service or out-of-service diagnostics tests. This includes verifying bandwidth throughput, frame loss, bit errors, and so on.
Third Generation (3G)
The third generation of digital wireless technology, as defined by the International Telecommunications Union (ITU). Third generation technology is expected to deliver data transmission speeds between 144 kbit/s and 2 Mbit/s, compared to the 9.6 kbit/s to 19.2 kbit/s offered by second generation technology.
Time Division-Synchronous Code Division Multiple Access (TD-SCDMA)
A 3G mobile communications standard found in UMTS mobile telecommunications networks in China as an alternative to W-CDMA. TD-SCDMA integrates technologies of CDMA, TDMA, and FDMA, and makes use of technologies including intelligent antenna, joint detection, low chip rate (LCR), and adaptive power control. With the flexibility of service processing, a TD-SCDMA network can connect to other networks through the RNC.
Transmission Control Protocol (TCP)
The protocol within TCP/IP that governs the breakup of data messages into packets to be sent using Internet Protocol (IP), and the reassembly and verification of the complete messages from packets received by IP. A connection-oriented, reliable protocol (reliable in the sense of ensuring error-free delivery), TCP corresponds to the transport layer in the ISO/OSI reference model.
Trivial File Transfer Protocol (TFTP)
A small and simple alternative to FTP for transferring files. TFTP is intended for applications that do not need complex interactions between the client and server. TFTP restricts operations to simple file transfers and does not provide authentication.
telecommunications management network (TMN)
A protocol model defined by ITU-T for managing open systems in a communications network. TMN manages the planning, provisioning, installation, and OAM of equipment, networks, and services.
terminal multiplexer (TM)
A device used at a network terminal either to multiplex multiple channels of low rate signals into one channel of high rate signals, or to demultiplex one channel of high rate signals into multiple channels of low rate signals.
A limitation on an amount, scale, or level. Changes will occur when a threshold is reached.
The maximum transmission rate of the tested object (system, equipment, connection, service type) when no packet is discarded. Throughput can be measured with bandwidth.
throughput capability
The data input/output capability of the data transmission interface.
time division multiplexing (TDM)
A multiplexing technology. TDM divides the sampling cycle of a channel into time slots (TSn, n is equal to 0, 1, 2, 3...), and the sampling value codes of multiple signals engross time slots in a certain order, forming multiple multiplexing digital signals to be transmitted over one channel.
time to live (TTL)
A specified period of time for best-effort delivery systems to prevent packets from looping endlessly.
Permissible degree of variation from a pre-set standard.
A program that prints the path to a destination. Traceroute sends a sequence of datagrams with the time-to-live (TTL) set to 1,2, and so on, and uses ICMP time exceeded messages that return to determine routers along the path.
traffic classification
A function that enables you to classify traffic into different classes with different priorities according to some criteria. Each class of traffic has a specified QoS in the entire network. In this way, different traffic packets can be treated differently.
trail termination source identifier (TTSI)
A TTSI uniquely identifies an LSP in the network. A TTSI is carried in the connectivity verification (CV) packet for checking the connectivity of a trail. If it matches the TTSI received by the sink point, the trail has no connectivity defect.
transmission delay
The period from the time when a site starts to transmit a data frame to the time when the site finishes the data frame transmission. It consists of the transmission latency and the equipment forwarding latency.
tributary protection switching (TPS)
A function that uses a standby tributary processing board to protect N tributary processing boards.
type-length-value (TLV)
An encoding type that features high efficiency and expansibility. It is also called Code-Length-Value (CLV). T indicates that different types can be defined through different values. L indicates the total length of the value field. V indicates the actual data of the TLV and is most important. TLV encoding features high expansibility. New TLVs can be added to support new features, which is flexible in describing information loaded in packets.
unavailable second
See unavailable time event.
Unspecified Bit Rate Plus
See Unified Menu Center.
See Universal Mobile Telecommunications System.
See user-to-network interface.
See usage parameter control.
user-end provider edge
user payload identifier
uninterruptible power module
uninterruptible power supply
Coordinated Universal Time
Unified Menu Center (UMC)
The Unified Menu Center provides menu information for handset customers and collects service parameters for customer transactions.
Universal Mobile Telecommunications System (UMTS)
A 3G mobile technology that will deliver broadband information at speeds up to 2 Mbit/s. Besides voice and data, UMTS will deliver audio and video to wireless devices anywhere in the world through fixed, wireless and satellite systems.
unavailable time event (UAT)
An event that is reported when the monitored object generates 10 consecutive severely errored seconds.
The process of sending data from a source to a single recipient.
In an access network, the direction that is far from the subscriber end of the link.A direction of message forwarding within a transaction that refers to the direction that responses flow from the user agent server back to the user agent client.
usage parameter control (UPC)
During communications, UPC is implemented to monitor the actual traffic on each virtual circuit that is input to the network. Once the specified parameter is exceeded, measures will be taken to control. NPC is similar to UPC in function. The difference is that the incoming traffic monitoring function is divided into UPC and NPC according to their positions. UPC locates at the user/network interface, while NPC at the network interface.
user-to-network interface (UNI)
The interface between user equipment and private or public network equipment (for example, ATM switches).
virtual network-network interface
The physical layer interface specification between DTE and DCE defined by the ITU-T. It complies with EIA/TIA-232.
The synchronous physical layer protocol defined by the ITU-T. It is used for communication between network access devices and the packet-based network. V.35 is mainly used in America and Europe.
virtual bridge
See variable bit rate.
See virtual channel.
VC trunk
See virtual container trunk.
See virtual channel connection.
virtual circuit connectivity verification
See virtual concatenation group.
virtual channel identifier
A virtual concatenation group applied in data service mapping, also called the internal port of a data service processing board.
very-high-data-rate digital subscriber line
See very-high-speed digital subscriber line 2.
very important person
virtual local area network
variable optical attenuator
See virtual path.
See virtual path identifier.
See virtual private LAN service.
virtual private network
See virtual private wire service.
VPN routing and forwarding
See Virtual Router Redundancy Protocol.
Virtual Router Redundancy Protocol (VRRP)
A protocol designed for multicast or broadcast LANs such as an Ethernet. A group of routers (including an active router and several backup routers) in a LAN is regarded as a virtual router, which is called a backup group. The virtual router has its own IP address. The host in the network communicates with other networks through this virtual router. If the active router in the backup group fails, one of the backup routers in this backup group becomes active and provides routing service for the host in the network.
See Voice over Internet Protocol.
Voice over Internet Protocol (VoIP)
A value-added service technology for IP calls. The VoIP service is a new IP telecom service. It can run on fixed and mobile networks and support flexible access points. Fees for VoIP subscribers are relatively low. Calls between VoIP subscribers who belong to the same carrier are free of charge.
variable bit rate (VBR)
One of the traffic classes used by ATM (Asynchronous Transfer Mode). Unlike a permanent CBR (Constant Bit Rate) channel, a VBR data stream varies in bandwidth and is better suited to non real time transfers than to real-time streams such as voice calls.
very-high-speed digital subscriber line 2 (VDSL2)
An extension of the VDSL technology, which complies with ITU G.993.2, supports multiple spectrum profiles and encapsulation modes, and provides short-distance and high-speed access solutions to the next-generation FTTx access service.
virtual channel (VC)
Any logical connection in the ATM network. A VC is the basic unit of switching in the ATM network and is uniquely identified by a virtual path identifier (VPI)/virtual channel identifier (VCI) value. It is the channel on which ATM cells are transmitted by a switch.
virtual channel connection (VCC)
A VC logical trail that carries data between two end points in an ATM network. A point-to-multipoint VCC is a set of ATM virtual connections between two or multiple end points.
virtual concatenation group (VCG)
A group of co-located member trail termination functions that are connected to the same virtual concatenation link.
virtual container trunk (VC trunk)
The logical path formed by some cascaded VCs.
virtual path (VP)
A bundle of virtual channels, all of which are switched transparently across an ATM network based on a common VPI.
virtual path identifier (VPI)
The field in the Asynchronous Transfer Mode (ATM) cell header that identifies to which virtual path the cell belongs.
virtual private LAN service (VPLS)
One kind of point-to-multipoint L2VPN services provided in public network, to connect isolated user sites by Metropolitan Area Network (MAN) or Wide Area Network (WAN), which makes the connection like LAN connection. It is a Layer 2 VPN technology based on Multiprotocol Label Switching (MPLS) and Ethernet. Through respective PE device, users in different locations can connect with each other by accessing VPLS network. From the user's perspective, the whole VPLS network is like a layer 2 switch network, users connect with each other like using LAN directly.
virtual private wire service (VPWS)
A technology that bears Layer 2 services. VPWS emulates services such as ATM, FR, Ethernet, low-speed TDM circuit, and SONET/SDH in a PSN.
voltage drop
The voltage developed across a component or conductor by the flow of current through the resistance or impedance of that component or conductor.
wide area network
See Wideband Code Division Multiple Access.
wavelength division multiplexing
waste electrical and electronic equipment
See weighted fair queuing.
weighted round robin
See wait to restore.
The local maintenance terminal of a transport network, which is located at the NE management layer of the transport network.
Wideband Code Division Multiple Access (WCDMA)
A standard defined by the ITU-T for the third-generation wireless technology derived from the Code Division Multiple Access (CDMA) technology.
wait to restore (WTR)
The number of minutes to wait before services are switched back to the working line.
weighted fair queuing (WFQ)
A fair queue scheduling algorithm based on bandwidth allocation weights. This scheduling algorithm allocates the total bandwidth of an interface to queues, according to their weights and schedules the queues cyclically. In this manner, packets of all priority queues can be scheduled.
A protection switching mode defined in ITU-T G.8132, which is applicable to packet-based T-MPLS ring networks and similar to SDH two-fiber bidirectional multiplex section protection (MSP). In this mode, the switching is triggered by the node that detects a failure. For details, see ITU-T G.841.
ITU-T standard for serial communications over synchronous digital lines. It is mainly used in Europe and Japan.
A data link layer protocol. It defines the communication in the Public Data Network (PDN) between a host and a remote terminal.
cross-connect and synchronous timing board
The OAM protocol introduced by the ITU-T. Besides the contents defined by IEEE802.1ag, ITU-T Recommendation Y.173 also defines the following combined OAM messages: Alarm Indication Signal (AIS), Remote Defect Indication (RDI), Locked Signal (LCK), Test Signal, Automatic Protection Switching (APS), Maintenance Communication Channel (MCC), Experimental (EXP), and Vendor Specific (VSP) for fault management and performance monitoring, such as frame loss measurement (LM), and delay measurement (DM).
Z interface extension
Extending the analogue subscriber to another place by extending the Z interface.
Updated: 2019-01-21

Document ID: EDOC1100020976

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