acronimos wan

7/30/2019 Acronimos WAN

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Acrnimo

Definicin

Trminosrelacionados/dispositivos/ejemplos o explicaciones

adicionales2B+D Synonymous with basic rate interface

(BRI) and basic rate access (BRA).Referring to the ITU-Tspecification for an ISDN

interface supporting two bearer(B) channels and one data (D)channel. See also ISDN and BRI.

ATM Asynchronous Transfer Mode. Theinternational standard for cell relay inwhich multiple service types (such asvoice, video, or data) are conveyed infixed-length (53-byte) cells. Fixed-length cells allow cell processing tooccur in hardware, thereby reducingtransit delays.

ATM is designed to takeadvantage of high-speedtransmission media, such as E3,SONET, and T3.

BECN Backward explicit congestionnotification. Bit set by a Frame Relay

network in frames traveling in theopposite direction of framesencountering a congested path.

DTE receiving frames with theBECN bit set can request that

higher-level protocols take flowcontrol action as appropriate.Compare with FE.

BRI Basic Rate Interface. ISDN interfacecomposed of two B channels and one Dchannel for circuit-switchedcommunication of voice, video, anddata.

Compare with PRI. See alsoBISDN, ISDN, and N-ISDN.

CHAP Challenge Handshake AuthenticationProtocol. Security feature supported onlines using PPP encapsulation thatprevents unauthorized access. CHAPdoes not itself prevent unauthorized

access, but merely identifies theremote end. The router or accessserver then determines whether thatuser is allowed access.

Compare with PAP

CIR Committed information rate. The rateat which a Frame Relay network agreesto transfer information under normalconditions, averaged over a minimumincrement of time. CIR, measured inbits per second, is one of the keynegotiated tariff metrics.

See also Bc.

CO Central office. The local telephonecompany office to which all local loops

in a given area connect and in whichcircuit switching of subscriber linesoccurs.

CPE Customer premises equipment.Terminating equipment, such asterminals, telephones, and modems,supplied by the telephone company,installed at customer sites, andconnected to the telephone company

Can also refer to any telephoneequipment residing on thecustomer site.


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network.CSU/DSU

CSU Channel service unit. Digital interfacedevice that connects end-userequipment to the local digitaltelephone loop.

Often referred to together withDSU, as CSU/DSU. See also DSU.

DSU Data service unit. Device used indigital transmission that adapts thephysical interface on a DTE device to atransmission facility, such as T1 or E1.

The DSU also is responsible for suchfunctions as signal timing.

Often referred to together withCSU, as CSU/DSU.

DCE 1. Data communications equipment(EIA expansion).2. Data circuit-terminating equipment(ITU-T expansion). Devices andconnections ofa communications network thatcomprise the network end of the user-

to-network interface. The DCE providesa physical connection to the network,forwards traffic, and provides aclocking signal used to synchronizedata transmission between DCE andDTE devices.

Modems and interface cards areexamples of DCE. Compare withDTE.

DDR Dial-on-demand routing. Techniquewhereby a router can automaticallyinitiate and close a circuit-switchedsession as transmitting stationsdemand. The router spoofs keepalivesso that end stations treat the sessionas active.

DDR permits routing over ISDNor telephone lines using anexternal ISDN terminal adaptoror modem.

DEMARC Demarcation point between carrierequipment and CPE

DLCI Data-link connection identifier. Valuethat specifies a PVC or an SVC in aFrameRelay network. In the basic FrameRelay specification, DLCIs are locallysignificant (connected devices mightuse different values to specify thesame connection). In theLMI extended specification, DLCIs areglobally significant (DLCIs specifyindividual end devices).

See also LMDS.

DTE Data terminal equipment. Device atthe user end of a user-networkinterface that serves as a data source,destination, or both. DTE connects to adata network through a DCE device(for example, a modem) and typicallyuses clocking signals generated by theDCE. DTE includes such devices ascomputers, protocol translators, andmultiplexers.

Compare with DCE.


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FECN Forward explicit congestionnotification. Bit set by a Frame Relaynetwork to inform DTE receiving theframe that congestion was experiencedin the path from source to destination.DTE receiving frames with the FECN bitset can request that higher-levelprotocols take flow-control action asappropriate.

Compare with BECN.

FrameRelay

Industry-standard, switched data linklayer protocol that handles multiplevirtual circuits using HDLCencapsulation between connecteddevices. Frame Relay is more efficientthan X.25, the protocol for which itgenerally is considered a replacement.

See alsoX.25

IETF Internet Engineering Task Force. Taskforce consisting of over 80 workinggroups responsible for developingInternet standards.

The IETF operates under theauspices of ISOC. See also ISOC.

ISDN Integrated Services Digital Network.Communication protocol offered bytelephone companies that permitstelephone networks to carry data,voice, and other source traffic.

See also BISDN, BRI, N-ISDN,and PRI

LAPB Link Access Procedure, Balanced. Datalink layer protocol in the X.25 protocolstack.LAPB is a bit-oriented protocol derivedfrom HDLC.

See also HDLC andX.25.

LAPD Link Access Procedure on the Dchannel. ISDN data link layer protocolfor the D channel. LAPD was derivedfrom the LAPB protocol and is designedprimarily to satisfy the signalingrequirements of ISDN basic access.Defined by ITU-T RecommendationsQ.920 and Q.921.

LCP Link control protocol. Protocol thatestablishes, configures, and tests data-link connections for use by PPP.

LMI Local Management Interface. Set of enhancements to the basic FrameRelay specification. LMI includessupport for a keepalive mechanism,which verifies thatdata is flowing; a multicastmechanism, which provides thenetwork server with itslocal DLCI and the multicast DLCI;global addressing, which gives DLCIsglobalrather than local significance in FrameRelay networks; and a statusmechanism, which provides an on-


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going status report on the DLCIs knownto the switch. Known as LMTin ANSIterminology.

MAN Metropolitan-area network. Networkthat spans a metropolitan area.Generally, a MAN spans a larger

geographic area than a LAN, but asmaller geographic area than a WAN.

Compare with LAN and WAN.

NCP 1. Network Control Program. In SNA, aprogram that routes and controls theflow of data between acommunications controller (in which itresides) and other network resources.2. Network Control Protocol. Series ofprotocols for establishing andconfiguring different network layerprotocols, such as for AppleTalk overPPP.3. Network control point. The processwithin the AT&T signaling network thatsends routing requests to a CustomerRouting Point (CRP), such as thenetwork interface controller (NIC)within the ICM.

NT1 Network termination 1. In ISDN, adevice that provides the interfacebetween customer premisesequipment and central office switchingequipment.

NT2 Network termination 2 In IntegratedServices Digital Networks (ISDN,) anintelligent device that may includefunctionality for OSI Layers 1 through 3(dependent on individual systemsrequirements.

PAP Password Authentication Protocol.Authentication protocol that allows PPPpeers to authenticate one another. Theremote router attempting to connect tothe local router is required to send anauthentication request. Unlike CHAP,PAP passes the password and the hostname or username in the clear(unencrypted). PAP does not itselfprevent unauthorized access butmerely identifies the remote end. Therouter or access server thendetermines whether that user isallowed access.

PAP is supported only on PPPlines. Compare with CHAP.

PBX Private branch exchange. Digital oranalog telephone switchboard locatedon the subscriber premises and used toconnect private and public telephonenetworks.

PDN 1. Public data network. Network


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operated either by a government (as inEurope) or by a private concern toprovide computer communications tothe public, usually for a fee. PDNsenable small organizations to create aWAN without the equipment costs oflong-distance circuits.2. Public/private/packet data network.Represents a public or private packet-based network, such as an IP or X.25network.

POP 1. Point of presence. In OSS, a physicallocation where an interexchangecarrier installed equipment tointerconnect with a local exchangecarrier (LEC).2. Post Office Protocol. Protocol thatclient e-mail applications use toretrieve mail from a mail server.

PPP Point-to-Point Protocol. Successor toSLIP that provides router-to-router andhost-to-network connections oversynchronous and asynchronouscircuits. Whereas SLIP was designed towork with IP, PPP was designed to workwith several network layer protocols,such as IP, IPX, and ARA. PPP also hasbuilt-in security mechanisms, such asCHAP and PAP. PPP relies on twoprotocols: LCP and NCP.

See also CHAP, LCP, NCP, PAP,and SLIP.

PRI Primary Rate Interface. ISDN interfaceto primary rate access. Primary rateaccess consists of a single 64-kbps Dchannel plus 23 (T1) or 30 (E1) Bchannels for voice or data. Comparewith BRI.

See also BISDN, ISDN, and N-ISDN.

PSTN Public switched telephone network.General term referring to the variety oftelephone networks and services inplace worldwide. Sometimes calledPOTS.

PVC Permanent virtual circuit (orconnection). Virtual circuit that ispermanently established. PVCs savebandwidth associated with circuitestablishment and tear down insituations where certain virtual circuitsmust exist all the time. In ATMterminology, called a permanentvirtual connection.

Compare with SVC. See alsovirtual circuit.

RBOC Regional Bell operating company.Seven regional telephone companiesformed by the breakup of AT&T. RBOCsdiffer from RBHCs in that RBOCs do not


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cross state boundaries.SDLC Synchronous Data Link Control. SNA

data link layer communicationsprotocol.SDLC is a bit-oriented, full-duplex serialprotocol that has spawned numerous

similarprotocols, including HDLC and LAPB.

See also HDLC and LAPB.

SLIP Serial Line Internet Protocol. Standardprotocol for point-to-point serialconnections using a variation of TCP/IP.

Predecessor of PPP. See alsoCSI and PPP.

SMDS Switched Multimegabit Data Service.High-speed, packet-switched,datagram-basedWAN networking technology offered bythe telephone companies.

See also CBDS.

SOHO Small office, home office. Networkingsolutions and access technologies foroffices that are not directly connected

to large corporate networks.SPID Service profile identifier. Number thatsome service providers use to definethe services to which an ISDN devicesubscribes. The ISDN device uses theSPID when accessing the switch thatinitializes the connection to a serviceprovider.

SS7 Signaling System 7. Standard CCSsystem used with BISDN and ISDN.Developed by Bellcore.

See also CCS.

SVC Switched virtual circuit. Virtual circuitthat is dynamically established on

demand andis torn down when transmission iscomplete. SVCs are used in situationswhere data transmission is sporadic.

See also virtual circuit. Called aswitched virtual connection

in ATM terminology. Comparewith PVC.

T1 Digital WAN carrier facility. T1transmits DS-1formatted data at1.544 Mbps through the telephone-switching network, using AMI or B8ZScoding.

Compare with E1. See alsoAMI,B8ZS, and DS-1.

TATDM Time-division multiplexing. Technique

in which information from multiple

channels can be allocated bandwidthon a single wire based on preassignedtime slots.Bandwidth is allocated to each channelregardless of whether the station hasdata to transmit.

Compare withATDM, FDM, andstatistical multiplexing.

TE1 Data terminal equipment (DTE) withintegrated ISDN support. In an ISDN,the System i system is a TE1.

See also terminal equipment 2.

TE2 Data terminal equipment (DTE) without See also terminal equipment 1.


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an ISDN interface. To communicatewith other equipment through an ISDN,this equipment must have the protocolconverted to one that can berecognized by the network. Forexample, a 7820 ISDN terminaladapter may be used.

X.25 ITU-T standard that defines howconnections between DTE and DCE aremaintainedfor remote terminal access andcomputer communications in PDNs.X.25 specifiesLAPB, a data link layer protocol, andPLP, a network layer protocol. FrameRelay has to some degree supersededX.25.

See also Frame Relay, LAPB,and PLP

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