Communications Terms Glossary
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Transcript of Communications Terms Glossary
COMMUNICATIONS TERMS GLOSSARYRed terms refer to protocols – communications rules and procedures
A
AAL
ATM Adaptation Layer .The AAL is what gives ATM the flexibility to carry entirely different types of services within the same format. It is important to understand that the AAL is not a network process but instead is performed by the network terminating equipment. Thus the networks task is only to route the cell from one point to another, depending on its header information.
AAL1 Transport for constant bit rate data traffic as voice, video or other continous user data . Contains timing information, CRC for error detection and corection for AAL overhead.
AAL2 Variable bit rate as video or other interrupted user data.Uses MINI CELS that have 3 octets header and payloads up to 64 bytes
AAL3 - 4 Merge of AAL3 & AAL4.Variable lenght frames and packets. Inefficient, is replaced by AAL5
AAL5 ATM adaptation layer 5 -1 VCC per trunk. Passport trunks over ATM carry DPRS traffic using AAL5 to convert frames to ATM cells.
ABCATM buss controller
ABR avaible bit rate* ABR is an ATM layer service category for which the limiting ATM layer transfer characteristics provided by the network may change subsequent to connection establishment.
ABSATM bearer service
ACDAn Automatic Call Distributor (ACD) is a telephone facility that manages incoming calls and handles them based on the number called and an associated database of handling instructions. Many companies offering sales and service support use ACDs to validate callers, make outgoing responses or calls, forward calls to the right party, allow callers to record messages, gather usage statistics, balance the use of phone lines, and provide other services.
ACELPAlgebraic code excited linear prediction
ADPCMadaptive differential pulse code modulation
ADSL Asymmetric Digital Subscriber Line - is a technology for transmitting digital information at a high bandwidth on existing phone lines to homes and businesses.
ADTFAllowed cell rate decrease time factor
AFIAuthority and format identifier
AISalarm indication signal called Blue Alarm
AMaccess module
APIHigh-level application programming interfaces (APIs), for example, APPC
A_PCRActual peak cell rate
APPNadvanced peer-to peer networking
APSAutomatic protection switching
AQMATM queue manager
ARNAdvanced Router Nortel
ARPadress resolution protocol
ASICapplication specific integrated circuit
ATM asynchronous transfer mode * Trunking system transparency * ( Routing System ) Connection-oriented routing * ATM can forward traffic at much higher rates than VNS
ATMARPATM address of the ATMARP server to enable address resolution
ATMIFATM interface
ATM MPEMultiprotocol ATM encapsulation
ATUAsynchronous Telemetry Unit
AYTare-you-there packet of attributes such as remote node name
BBBC-IE
broadband bearer capability information element
BCbuss controller
BCIBackward Congestion Indication
BECNbackward explicit congestion notification
BER bit error rate is percentage of bits with errors in total bits received.
BERT bit error ratio (rate) testing.
BGP(4)border gateway protocol (version 4)
BNCBNC Option pt cablu coax The basic BNC connector is a male type mounted at each end of a cable. This connector has a center pin connected to the center cable conductor and a metal tube connected to the outer cable shield. A rotating ring outside the tube locks the cable to any female connector.
BoSSBayStack Operating System Switching Software
BooTPbootstrap protocol
BPDUsBridge Protocol Data Units
BTDSbit transparent data service
BTDSH bit transparent data service * It is required for signaling only in CCS( ts 24 for DS1, ts 16 for E1)
BUSbroadcast and unknown server
BWBandwidth
BWoDdynamic "Bandwidth on demand" to provide extra bandwidth for traffic peaks.
CCA
connection administrator
CACconnection admission control
Call Center
A call center is a physical place where customer and other telephone calls are handled by an organization, usually with some amount of computer automation. Typically, a call center has the ability to handle a considerable volume of calls at the same time, to screen calls and forward them to someone qualified to handle them, and to log calls. Call centers are used by mail-order catalog organizations, telemarketing companies, computer product help desks, and any large organization that uses the telephone to sell or service products and services. Vi rtual call center is a call center in which the organization's representatives are geographically dispersed, rather than being situated at work stations in a building operated by the organization. Virtual call center employees may be situated in groups in a number of smaller centers, but most often they work from their own homes. This is an attractive arrangement for many employees: the hours are often flexible, and there's no dress code or commute. For the organization, the virtual call center model saves housing and equipment costs and can lead to lower employee turnover rates, which tend to be high for physical call centers.
CallPilot
CallPilot 4.0 provides a variety of new unified messaging features, as well as Cost of Ownership improvements designed to help reduce on-going management and maintenance costs. CallPilot is a unified messaging application for businesses using Meridian 1 PBX phone systems, Meridian SL-100, Communication Server 1000, and CPE Centrex systems. It combines voicemail, e-mail and fax messages into a single mailbox — accessible by phone, any desktop PC, or mobile e-mail enabled devices (PDAs). CallPilot Unified messaging provides a compelling solution for businesses that are looking at reducing costs, improving productivity, and staying connected to their customers and suppliers.
CAPcall accept packet
CAS Component Administration System or Channel associated signaling: signaling in same or in different channel permanent associated. CAS protocols : R1, R2, DTMF, MF
C-bit The 3th, 5th and 7th overhead (bits in a frame, not in the payload , for signalling) bits in a DS3 signal's M-subframes (submultiframe, division of multiframe that contains multiple frames)
CbComited burst
CBCconnection bandwidth control
CBR constant bit rate * Differ from VBR; SAD (Speech activity detection) feature changes voice from CBR traffic to VBR traffic
CCRCustomer Call Routing
CCS Common channel signaling: one channel for all signaling functions of a group of voice channels CCS protocols : DPNSS, QSIG, CCS7. It requires BTDS for signaling- ts 24 for DS1, ts 16 for E1
CAMECDMA (code-division multiple access) refers to any of several protocols used in so-called second-generation (2G) and third-generation (3G) wireless communications. As the term implies, CDMA is a form of multiplexing, which allows numerous signals to occupy a single transmission channel, optimizing the use of available bandwidth. The technology is used in ultra-high-frequency (UHF) cellular telephone systems in the 800-MHz and 1.9-GHz bands
CDVcell delay variation
CDVTCell delay variation tolerance also known as network jitter (tolerance)
CELPCode excited linear prediction
CES circuit emulation service Contivity Extranet Switch
CFPControl and function processor
Cgcongestion level
CIDCustomer identifier
CIF
Cost,Insurance and Freight(... named port of destination) means that the seller delivers when the goods pass the ship's rail in the port of shipment. The seller must pay the costs and freight necessary to bring the goods to the named port of destination .The CIF term requires the seller to clear the goods for export. This term can be used only for sea and inland waterway transport. If the parties do not intend to deliver the goods across the ship's rail, the CIP term should be used.
CIO Chief Information Officer (CIO) is a job title commonly given to the person in an enterprise responsible for the information technology and computer systems that support enterprise goals.
CIP Carriage and Insurance Paid To(... named place of destination) means that the seller delivers the goods to the carrier nominated by him but the seller must in addition pay the cost of carriage necessary to bring the goods to the named destination. This means that the buyer bears all risks and any additional costs occurring after the goods have been so
delivered. However, in CIP the seller also has to procure insurance against the buyer's risk of loss of or damage to the goods during the carriage. Consequently, the seller contracts for insurance and pays the insurance premium.If subsequent carriers are used for the carriage to the agreed destination, the risk passes when the goods have been delivered to the first carrier. The CIP term requires the seller to clear the goods for export. This term may be used irrespective of the mode of transport including multimodal transport.
CLConnectionless Data
CLPcell lost priority
CLRcell loss ratio
COConnection Oriented Data
COICommunity of interest
COMPANION WIRELESS
The name for the communication systems which use radio technology to transmit and receive signals between its components and the Business Communications Manager.
CONTACT CENTER
A contact center (also referred to as a customer interaction center or e-contact center) is a central point in an enterprise from which all customer contacts are managed. The contact center typically includes one or more online call centers but may include other types of customer contact as well, including e-mail newsletters, postal mail catalogs, Web site inquiries and chats, and the collection of information from customers during in-store purchasing. A contact center is generally part of an enterprise's overall customer relationship management (CRM).A contact center would typically be provided with special software that would allow contact information to be routed to appropriate people, contacts to be tracked, and data to be gathered
CLP Cell Loss Priority
COPSCommon Open Policy Services
COSclass of service
CP control processor * Control processors manage the processor cards on the shelf and provide basic system capabilities.
CPCScommon part convergence sublayer
CPEcustomer premise equipment
CPNDCalling party name display
CQCcell queue control
CQMcell queue memory
CRcall route
CRCCRC-4 (Cyclic Redundancy Check 4) is a form of cyclic redundancy checking (a method of
checking for errors in transmitted data) that is used on E-1 trunk lines. CRC-4 is structured in a multiframe consisting of 16 frames numbered 0 to 15. The CRC-4 multiframe is then divided into two eight frame Sub-Multiframes (SMF) called SMF I and SMF II. Each SMF contains four CRC-4 bits designated C1, C2, C3, and C4. Through multiplication and division processes, the CRC-4 bits sent in each SMF are compared to each other and if they match, the frame is considered error free. Bit 1 is used for the CRC-4 bits. CRC-4 support is required for all network switches in Europe. However, some older switches including private branch exchanges (PBXs) do not support CRC-4.
CRMcustomer relationship management analytics comprises all programming that analyzes data about an enterprise's customers and presents it so that better and quicker business decisions can be made.
CRPcall request packet
CRScall redirection server
C/RCommand/Response
CSE MXSuccession Communication Server for Enterprise Multimedia Xchange
CSMA/CD
The Ethernet carrier sense multiple access/collision detection (CSMA/CD) protocol operates in half-duplex mode, allowing either data transmission or reception, but never both at the same time. Point-to-point network connections, such as DTE-to-switch ports, do not need CSMA/CD to resolve media access contention from multiple devices; therefore, point-to-point network connections allow a file server to transmit frames to a switch while simultaneously receiving frames from the same switch. This two-way, non-CSMA/CD full-duplex communication provides an effective bandwidth of 200 Mb/s between two 100 Mb/s devices.
CSRMcall server resource modules
CS-ACELP Conjugated structure-algebraic coded excited linear prediction diff LD-CELP 80bytes-8kb/sec
CSV Comma Separated Values format
CTDCell Transfer Delay
CTE Computer Telephony Engine
CTICTI ( computer-telephony integration), or sometimes simply "computer telephony," is the use of computers to manage telephone calls. The term is used in describing the computerized services of call centers, such as those that direct your phone call to the right department at a business you're calling.
CTSClear To Send - modem
CUG Closed User Group facilitate folosita in X25 pentru cresterea sigurantei datelor din retea prin limitarea accesibilitatii
D
Ddestination
DCCData country code
DCEData circuit equipment (MASTER) Data Communications Equipment (DCE) device. In practical terms, the DCE is usually a modem and the DTE is the computer itself, or more precisely, the computer's UART chip. For internal modems, the DCE and DTE are part of the same device.
DCMEDigital circuit multiplication equipment
DCRdestination call router
DCSdata collection system
DDSDigital Data Service
Deemission delay
DEdiscard eligible
DGCRADynamic generic cell rate algorithm
DIGlocal digital loopback test
DivX
DivX (Digital Video Express) is a hacked MPEG4 codec allowing the encoding (and decoding) of high-quality MPEG4 video streams. MPEG4 is designed for low-bitrate applications and thus offers an excellent size/quality -ratio. As such DivX is ideal for very high quality DVD backups and other applications requiring high video quality at limited space.
Dmmeasured delay
DMLT Distributed Multi-LinkTrunking
Dppropagation delay
DLCIData Link Connection Identifier(I=ID) - Frame Relay protocol
DLRdata link routing
DDPDelivered Duty Paid means that the seller fulfils his obligation to deliver when the goods have been made available at the named place in the country of importation. The seller has to bear the risks and costs, including duties, taxes and other charges of delivering the goods thereto, cleared for importation. Whilst the EXW term represents the minimum obligation for the seller, DDP represents the maximum obligation. This term should not be used if the seller is unable directly or indirectly lo obtain the import licence. If the parties wish the buyer to clear the goods for importation and to pay the duty, the term DDU should be used. If the parties wish to exclude from the seller's obligations some of the costs payable upon importation of the goods (such as value added tax(VAT)), this should be made clear by adding words to this
effect:"Delivered duty paid, VAT unpaid named place of destination)"
DNDirectory number
DNAdynamic network address
DNS Domain Name System. DNS servers are strategically located on the Internet to convert domain names to IP addresses.
DPdiscard priority (discard policy) Dialing plan
DPFDynamic Protocol Filtering (IBM)
DPNdynamic packet network / data packet network
DPNSS 1digital private network signaling system no.1
DPRS dynamic packet routing system * Connectionless routing ; is responsible for routing Passport traffic such as frame relay, APPN, and DPN-100. DPRS=FRframe relay+APPN(advanced peer to peer networking)+SLA DNR +DNA gateway
DQdestination queue indetifier
DS1
digital signal level 1
Digital Signal Designator Data Rate DS0 Multiple T-Carrier E-Carrier
DS0 64 Kbps 1 - -
DS1 1.544 Mbps 24 T-1 -
- 2.048 Mbps 32 - E1
DS1C 3.152 Mbps 48 - -
DS2 6.312 Mbps 96 T-2 -
- 8.448 Mbps 128 - E2
- 34.368 Mbps 512 - E3
DS3 44.736 Mbps 672 T-3 -
- 139.264 Mbps 2048 - E4
DS4/NA 139.264 Mbps 2176 - -
DS4 274.176 Mbps 4032 - -
- 565.148 Mbps 4 E4 channels - E5
DS1CA DS level and framing specification for digital signals in the North American digital transmission hierarchy. A DS1C signal uses 48 PCM channels and has a transmission rate of 3.15 Megabits per second, twice that of DS1.
DSL DSL (Digital Subscriber Line) is a technology for bringing high-bandwidth information to homes and small businesses over ordinary copper telephone lines. xDSL refers to different variations of DSL, such as ADSL, HDSL, and RADSL
DSxdigital signal level x
DS/DSCPThe Business Policy Switch includes the capability to enhance your network traffic management. For each packet, there is an octet in the packet header, the DiffServ (DS) field, that you can designate for specific service. For IP packets, six bits of the DS field is the DiffServ Code Point (DSCP). DSCP value defines how the packet is to be treated as it travels through the network.
DSPDigital signal processing
DSUData set unit
DTE
data terminating equipment {host)Short for Data Terminal Equipment, a device that controls data flowing to or from a computer. The term is most often used in reference to serial communications defined by the RS-232C standard. This standard defines the two ends of the communications channel as being a DTE and Data Communications Equipment (DCE) device. In practical terms, the DCE is usually a modem and the DTE is the computer itself, or more precisely, the computer's UART chip. For internal modems, the DCE and DTE are part of the same device.
DTMFdual tone multi frequency
DWDM Dense wavelength division multiplexing (DWDM) is a technology that puts data from different sources together on an optical fiber, with each signal carried at the same time on its own separate light wavelength.
EE1
european level 1
EAPexternal address plan
EAPMexternal address plan manager
EBRedge-based rerouting
ECRequivalent cell rate
EFCIexplicit forward congestion indication
EGHextended Gibbens-Hunt method
EGPexterior gateway protocol
EIRexcess information rate
EMEnterprise module
EOMend of message
Epend point
EPemission priority
EPDearly packet discard
ERExplicit rate
ESCON
Enterprise Systems Connection is a marketing name for a set of IBM and vendor products that interconnect S/390 computers with each other and with attached storage, locally attached workstations, and other devices using optical fiber technology and dynamically modifiable switches called ESCON Directors.
ESDthe ElectroStatic Discharge jack on the shelf assembly
ESFExtended superframe
ESIEnd system identifier
ExEuropean level x
EXWEx Works conditia de livrare cea mai comoda pentru vanzator: trebuie sa puna marfa ambalata la dispozitia cumparatorului, care este obligat sa o incarce pe cheltuiala si riscul sau.
FFAST Flexible Advanced StackingTechnology
FBTDSframe aligned BTDS
FCIForward Congestion Indication
FCS Frame Check Sequence is utilized between the access device and the network to ensure bit integrity of the frame (FR)
FDCRfinal destination call router
FEAC Far End Alarm and Control
FEBE Far End Block Error
FERF Far End Receive Failure -Prima denumire (in documentatia mai veche ) pentru RDI
FDDIFiber distributed data interface
FECNforward explicit congestion notification
FFPfast forwarder process
FISfax idle suppression
FPfunction processor * Function processors provide communication connections and services.
FPPfast packet processor
FR
Frame relay - a high-speed, packet switching WAN protocol designed to provide efficient, high-speed frame or packet transmission with minimum delay. Frame relay uses minimal error detection and relies on higher level protocols for error control.Frame relay is a telecommunication service designed for cost-efficient data transmission for intermittent traffic between local area networks LANs and between end-points in a wide area network WAN Frame relay puts data in a variable-size unit called a frame and leaves any necessary error correction (retransmission of data) up to the end-points, which speeds up overall data transmission. For most services, the network provides a permanent virtual circuit, which means that the customer sees a continous, dedicated connection without having to pay for a full-time leased line, while the service provider figures out the route each frame travels to its destination and can charge based on usage.
FR-ATMframe relay over ATM
FRDTEFrame relay DTE (Data termination equipment) access service interconnects a Passport 6400 node and other frame relay devices. You can use this service to connect private networks to public networks, private networks to private networks, private networks to private networks through public networks
FRFFrame relay forum
FRUNIFrame relay UNI (User to network)
FTPfile transfer protocol
FE1 fractional E1
FT1 fractional T1
FTTB FTTC
Fiber to the curb"(FTTC) refers to the installation and use of optical fiber cable directly to the curbs near homes or any business environment as a replacement for "plain old telephone service" (POTS). The term "fiber to the curb" recognizes that optical fiber is already used for most of the long-distance part of your telephone calls and Internet use. Unfortunately, the last part - installing fiber to the curb - is the most expensive. Fiber to the curb implies that coaxial cable or another medium might carry the signals the very short distance between the curb and the user inside the home or business. "Fiber to the building" (FTTB) refers to installing optical fiber from the telephone company central office to a specific building such as a business or apartment house. ". Hybrid Fiber Coax (HFC) is an example of a distribution concept in which optical fiber is used as the backbone medium in a given environment and coaxial cable is used between the backbone and individual users (such as those in a small corporation or a college environment).
GGAN
Global Area Network
gatewayLinks to other networks are called gateways a device (as a router ) serving as an entry A system that links two different types of networks and enables them to communicate with each other. The Business Communications Manager BCM can provide the gateway to an intranet or internet .into a network.
GBIC Gigabit Interface Converter
GbpsGigabits per second
GCACgeneric connection admission control
GCMglobal cache manager
GCRAgeneric cell rate algorithms
GFCgeneric flow control
.gif Graphical Interchange Format (.gif)
GIS
Geographic Information System ; an analytic framework for managing and integrating data. A GIS can be viewed in three ways: 1 The Database View: A GIS is a unique kind of database of the world—a geographic database (geodatabase); 2 The Map View: A GIS is a set of intelligent maps and other views; 3 The Model View: A GIS is a set of information transformation tools that derive new geographic datasets
GPRSgeneral packet radio services
GPS
Global Positioning System is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. GPS receivers take this information and use triangulation to calculate the user's exact location. Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, with distance measurements from a few more satellites, the receiver can determine the user's position and display it on the unit's electronic map.
GREGeneric routing encapsulation
GSMGlobal System for Mobile communication
GUIA GUI is a graphical (rather than purely textual) user interface to a computer. As you read this, you are looking at the GUI or graphical user interface of your particular Web browser. The term came into existence because the first interactive user interfaces to computers were not graphical; they were text-and-keyboard oriented and usually consisted of commands you had to remember and computer responses that were infamously brief.
H
HDLC
high-level data link control Layer 2 of the OSI model is the data link layer. One of the most common layer 2 protocols is the HDLC protocol. In fact, many other common layer 2 protocols are heavily based on HDLC, particularly its framing structure: namely, SDLC, SS#7, LAPB ,LAPD and ADCCP. The basic framing structure of the HDLC protocol is shown below:HDLC uses zero insertion/deletion process (commonly known as bit stuffing) to ensure that the bit pattern of the delimiter flag does not occur in the fields between flags. The HDLC frame is synchronous and therefore relies on the physical layer to provide method of clocking and synchronizing the transmission and reception of frames.The HDLC protocol is defined by ISO for use on both point-to-point and multipoint (multidrop) data links. It supports full duplex transparent-mode operation and is now extensively used in both multipoint and computer networks.
HDSL
High-Data-Rate Digital Subscriber Line. One of four DSL technologies. HDSL delivers 1.544 Mbps of bandwidth each way over two copper twisted pairs. Because HDSL provides T1 speed, telephone companies have been using HDSL to provision local access to T1 services whenever possible. The operating range of HDSL is limited to 12,000 feet (3658.5 meters), so signal repeaters are installed to extend the service. HDSL requires two twisted pairs, so it is deployed primarily for PBX network connections, digital loop carrier systems, interexchange POPs, Internet servers, and private data networks.
HECheader error control
HgmFrUni Dna HuntGroupMember
HPHolding priority
HTDS HDLC transparent data service( HDLC = High level data link control ); see also BTDS (bit transparent data service) & VTDS(voice transparent data service)
HTMLHyperText Markup Language
HTTP Hypertext Transfer Protocol (HTTP)The set of rules used for exchanging text, graphic images, sound, video, and other multimedia files on the world wide web.
HUB
Hubs are devices with many ports (jacks into which network cables can plug in); a hub is simply a multi-port repeater. It takes data signals in through one port, and repeats everything out through all the other ports, hoping that one of the computers plugged into it is the destination computer.The disadvantage of this behavior is that it causes unnecessary traffic. By sending out the same signal to every computer, it clogs up the lines keeping them busy and preventing other data from being sent over them.
H323
Two standards have emerged for signaling and control of VoIP telephony: ITU-T H.323 and the IETF Session Initiated Protocol (SIP). These protocols, although resulting in the same end-user service (telephony), differ in the approach to providing signaling functions. H.323 is based more on a monolithic bloc derived from H.320 for traditional of the traditional circuit-switched ISDN multimedia, and SIP favors a more lightweight approach based on HTTP. The ITU-T Recommendation H.323 specification defines four different H.323 entities as the functional units of a complete H.323 network that can be packaged together into a co-located product. These include gatekeepers, multipoint control units (MCUs), gateways, and terminals.
I
ICDInternational code designator
ICMPinternet control message protocol
ICPIMA control protocol
ICRInitial cell rate
IDOL Intelligent Data Operating Layer (IDOL), platforma care formeaza o intelegere conceptuala si contextuala a informatiilor
IDSAn IDS (Intrusion Detection System) is a network security system designed to identify intrusive or malicious behavior via monitoring of network activity. The IDS identifies suspicious patterns that may indicate an attempt to attack, break in to, or otherwise compromise a system. An IDS can be network-based or host-based, passive or reactive, and can rely on either misuse detection or anomaly detection
IDPinternet datagram protocol
IEInformation element
IGMP
Internet Group Management Protocol (IGMP) is used by IP Multicast routers to learn about the existence of host group members on their directly attached subnets (see RFC 2236). The IP Multicast routers get this information by broadcasting IGMP queries and listening for IP hosts reporting their host group memberships. This process is used to set up a client/server relationship between an IP Multicast source that provides data streams and the clients that want receive data.
IGRPInterior Gateway Routing Protocol
IISPinterim interswitch signaling protocol
ILSinterLAN switching ( Connectionless routing)
ILSIPILS routing stack
ILMIinterim(Integrated) local management interface
IMAinverse multiplexing for ATM
IMUXInverse multiplexing for frame-cell trunks
InARPinverse ARP
IPinternet protocol *Transmission control protocol/Internet protocol (TCP/IP) is a group of protocols that defines a common set of rules and standards that enable networks and hosts to communicate. IP isthe routed or network layer protocol of TCP/IP and is one of the most popular internetworking protocols.
IP addressing A system for assigning numbers to network subdivisions, domains, and nodes in TCP/IP
networks
IPIFRIP interface over frame relay
IPIVCIP interface over virtual circuit
IPNG IP Next Generation. A term used to describe the efforts of the Internet Engineering Task force to cope with the explosive growth of the Internet by defining the next generation of Internet Protocol
IPOAInternet Protocol over ATM
IPsec
Internet Protocol Security is a framework for a set of protocols for security at the network or packet processing layer of network communication. Earlier security approaches have inserted security at the application layer of the communications model. IPsec is said to be especially useful for implementing virtual private networks and for remote user access through dial-up connection to private networks. A big advantage of IPsec is that security arrangements can be handled without requiring changes to individual user computers.
IPX
internetwork packet exchange * A Novell LAN protocol that creates maintains and terminates connections between network devices* The Passport 6400 internetwork packet exchange (IPX) service is a connectionless network layer protocol that delivers datagram packets on a best-effort basis. IPX uses the information in the routing information protocol packets to determine current information about the network topology. The service advertisement protocol (SAP) allows printers, file servers, and gateways to announce their availability to nodes on the network. IPX also allows direction or control of services provided on the network by filtering the packets.
ISAC ISDN Subscriber Access Controller (ISAC)
ISCsInternational switching centers
ISDLCIntegrated Services Digital Line Card
ISDN
ISDN (Integrated Services Digital Network) is a set of CCITT/ITU standards for digital transmission over ordinary telephone copper wire as well as over other media. Home and business users who install an ISDN ADAPTER (in place of a telephone modem) receive Web pages at up to 128 Kbps compared with the maximum 56 Kbps rate of a modem connection. ISDN requires adapters at both ends of the transmission so your access provider also needs an ISDN adapter
ISPInternet service provider
ISVNInteroperability Software Version Numbers
IVDintegrated voice and data
IVR
Interactive Voice Response (IVR) is a software application that accepts a combination of voice telephone input and touch-tone keypad selection and provides appropriate responses in the form of voice, fax, callback, e-mail and perhaps other media. IVR is usually part of a larger application that includes database access
J
jabber In local area networks, transmission by a data station beyond the time interval allowed by the protocol.
JIT
just-in-time - compiler in the Java programming language and environment, a just-in-time (JIT) compiler is a program that turns Java bytecode (a program that contains instructions that must be interpreted) into instructions that can be sent directly to the processor
.jpeg, .jpg Joint Photographic Experts Group (.jpeg, .jpg)
JTIDS Joint Tactical Information Distribution System
JTRB Joint Telecommunications Resources Board
K
KTSkey telephone system In a local environment, obstacle such as a mountain range or the edge of a terminals and equipment that provide immediate building. Note: The knife-edge effect is access from all terminals to a variety of telephone explained by Huygens’ principle, which states that a services without attendant assistance. Note: A well-defined obstruction to an electromagnetic wave KTS may interface with the public switched telephone
L
LACP
Link Aggregation (LA) allows you to create and manage a trunk group. You can control and configure a trunk group automatically through the use of the Link Aggregation Control Protocol (LACP). 802.3ad provides an industry standard method for bundling multiple links together to form a single trunk between two networking devices. Trunks that conform to the 802.3ad standard are Link Aggregation Groups (LAGs). BoSS 3.1 supports 2 types of trunks•Dynamic LAG•MLTA trunk group that is formed by Link Aggregation is called a Link Aggregation group (LAG), and a trunk group that is formed by BayStack Multilink Trunking is called a Multilink trunk (MLT) group.
LAPD Link Access Protocol Dlink layer protocol specified by CCITT ( used by FR)
LAN local area network
LANE LAN emulation over ATM Parti din reteaua ATM se comporta ca o retea LAN Virtuala (devices ATM interactioneaza transparent cu devices LAN)
LCLogical channel ; A logical channel (LCh) is the instance of a path on a trunk.LCh components existsonly on the receiving side of a trunk
LCD loss of cell delineation
LCN logical channel number
LCM local cache manager
LCo logical connection
LDAP
Lightweight Directory Access Protocol, is an Internet protocol that email and other programs use to look up information from a server. Ex .Search for all people located in Chicago whose name contains "Fred" that have an email address. Please return their full name, email, title, and description."
LD-CELP Low delay- code excited linear prediction diff CS-ACELP 5bytes-16kb/sec
LDM Legacy data module
LDS link delay synchronization
LEC LAN emulation client
leased dedicated
LES LAN emulation server
LG link group
LGT Link group table
LIS logical IP subnet
LLB Local Analog Loopback -modem
LLc Logical link control
LMI Link management interface
LMID logical module identifier
LN Logical network
LNNI LAN emulation network-to-network interface specification
LNN logical network number
LOC Location code
LODS loss of delay synchronization
LP Logical Processor
LPD late packet discartd
LPT Logical Processor type
LRC Longitudinal redundancy check
LSA link state advertisement
LSAP Multiple link service access points
LSB Least significant bit
LTP Light-weight trunk protocol
MMAC media access control
MAG Magellan access switch
MAS Master
MBG Minimum bandwidith guarantee
M-bit Bit 1 of 5th, 6th,7th Msubframes in a DS3 signal
MBS maximum burst size
MCDN Network Signaling Protocol -Meridian 1 ISDN primary rate interface protocol * Meridian 1 customer defined network
MCR minimum cell rate
MCS Multiservice cut-through switching
MD Management device
MDA
Media Dependent Adapters. An independent module, generally featuring an input and/or output port that interfaces to some style of media connector. <!--[if ppt]--> –<!--[endif]-->
MDM Preside Multiservice Data Manager
MDP Management Data Provider
MIB management information bases
MID module identifier - second module level in the DPRS addressing hierarchy
MLTMultiLink Trunk (MLT) is a point-to-point connection that aggregates multiple ports so that they logically act as a single port with the aggregated bandwidth. Grouping multiple ports into a logical link allows you to achieve higher aggregate throughput on a switch-to-switch or switch-to-server application. MultiLink Trunking provides media and module redundancy.
MP3 Motion Picture Experts Group, Audio Layer 3“ sau MPEG Layer III
MPANL Multiservice Passport Access Network Link
MPE multiprotocol encapsulation
MPE -ATM multiprotocol encapsulation service
MPEG4
MPEG-4 is an ISO/IEC standard developed by MPEG (Moving Picture Experts Group), the committee that also developed the Emmy Award winning standards known as MPEG-1 and MPEG-2. These standards made interactive video on CD-ROM and Digital Television possible.
MPID module process identifier- third and lowest level in the DPRS so RID (Routing), MID(module), MPID (module process) addressing hierarchy
MPLS
Multiprotocol Label Switching is a standards-approved technology for speeding up network traffic flow and making it easier to manage. MPLS involves setting up a specific path for a given sequence of packets, identified by a label put in each packet, thus saving the time needed for a router to look up the address to the next node to forward the packet to. MPLS is called multiprotocol because it works with the Internet Protocol , Asynchronous Transport Mode (ATM), and frame relay network protocols
MPOA Multiprotocol over atm
MPS Multiple Priority System
MTU maximum transmission unit
music on hold
in a state of interruption during a telephone call when one party switches to another line without totally disconnecting the other party
MVP Multi purpose voice platform - processor
MVP-E MVP enhanced (echo cancellation)
MVR multiple virtual router
M13 A DS3 framing format or the multiplex between DS1 and DS3 levels
NNBMA non broadcast multi acces
NCS Network Clock Synchronization
Nep nailed up end point
NFAS non-facility associated signaling or multiple links per D-channel (nB+D)
NHRP next hop resolution protocol
NHS next hop server
NIS Network interface specification
NMIS Network management interfaces
NMM network management MIB ( MIB= management information bases)
NMS Network Management System
NN Network node
NNINetwork network (or node) interface * The Passport 6400 frame relay network-to-network interface (NNI) service provides a communication interface between two frame relay networks. This service receives, processes, and transmits the network status signaling information through the network. The end user receives accurate information about the network
NPVC Nailed up permanent virtual connection ( opus SVPC)
NRP nailed-up relay point
nrtVBR non-real-time VBR
NS NetworkSynchronization
NSAP Network service access point
NTP Network time protocol
NUI Network User Identification
OOAM Operational administration maintenance
OC Optical Carrier, specifies the speed of fiber optic networks conforming to the SONET standard OC-3 = 155.52 Mbps
OEM
Original Equipment Manufacturer, which is a misleading term for a company that has a special relationship with computer producers. OEMs buy computers in bulk and customize them for a particular application. They then sell the customized computer under their own name. The term is really a misnomer because OEMs are not the original manufacturers -- they are the customizers.
OM-P Open management system for Passport
OSI Open system interconnection
OSPF open shortest path first
PP bit priority bit
PA (trunk) Path administrator
PABX
A PBX (private branch exchange) is a telephone system within an enterprise that switches calls between enterprise users on local lines while allowing all users to share a certain number of external phone lines. The main purpose of a PBX is to save the cost of requiring a line for each user to the telephone company's central office. The PBX is owned and operated by the enterprise rather than the telephone company (which may be a supplier or service provider, however)
PANL Passport access network link
payload The information bits of a frame or cell, are not part in overhead
PBRSde ex 2^15-1 A 215- 1 pseudorandom bit sequence PRBS n=15
PCM Pulse code modulation
PCMCIA Personal Computer Memory Card International Association
PCRpeack cell rate * The unit of measurement for PCR is cells per second (cells/s) but the Passport trunk and topology systems work in bandwidth units of bits per second (bps). The AtmAccess component converts the PCR value to a bandwidth value measured in bits/s using the conversion formula of 1 cell/s = 384 bit/s.The ACR is the minimum of the PCR, CCR, and
actual shaping rate (ASR). * Passport Carrier release
PDC processor daughter card * Processor data card
PDH Plesiochronous digital hierarchy
PDU protocol data unit
PHY Physical Layer Entity
PID process identifier
PLC permanent logical connection
PLCP Physical Layer Convergence Protocol
PNCS passport network clock synchronization
PNNI private network network(node) interface
POMS Port management system
PORSpath-oriented routing system * (Connection-oriented routing voice transport &voice networking) PORS is the routing system used by the voice networking service.PORS=VOICE+BTDS+HTDS
PORSvc Path-Oriented Routing System virtual circuit
Port Mirroring
method of monitoring network traffic that forwards a copy of each incoming and outgoing packet from one port of a network switch to another port where the packet can be studied. A network administrator uses port mirroring as a diagnostic tool or debbuging feature, especially when fending off an attack. Port mirroring can be managed locally or remotely.
PNCS Passport Network Clock Synchronization
PNNI Private network network (or node) interface
PPD partial packet discard
PPP
Point to point protocol service is a data link layer protocol service that provides packet transfer between two dedicated WAN peers. Packet transfers are full duplex and sequential.A protocol for creating a TCP/IP connection over both synchronous and asynchronous systems. PPP provides connections for host to network or between two routers, It also has a security mechanism. PPP is well known as a protocol for connections over regular telephone lines using modems on both ends. This protocol is widely used for connecting personal computers to the internet.
PQC Passport queue controller
PRBS Pseudorandom bit sequence, a test pattern for live random traffic
PRI primary rate interface
PROTOCOL
The special set of rules that end points in a telecommunication connection use when they communicate. Protocols exist at several levels in a telecommunication connection. For example, there are protocols for the data interchange at the hardware device level and protocols for data interchange at the application program level. In the standard model known as Open Systems Interconnection OSI there are one or more protocols at each layer in the telecommunication exchange that both ends of the exchange must recognize and observe. Protocols are often described in an industry or international standard
PSTN public switched telephone network
PTI payload type indicator
PTS Passport trace system
PVID Port VLAN Identifier
PVC Permanent virtual connecton
PVG Packet Voice Gateway
QQDU quantization distortion unit
QoS
quality of service defined by: PCR peack cell rate & SCR sustained cell rateCDV & CDVT cell delay variation & cell delay variation toleranceCTD cell transfer ratio &CLR cell loss ratio
QRSSA quasi random signal source 2 ^20 pattern cu 14 octeti sigur 0 din 20
QSIG Q interface signaling PROTOCOL;
RRADIUS Remote Authentication Dial In User Services
RAI Remote Alarm Indication - Yellow
RARP reverse address resolution protocol
RCOS routing class of service
RDI remote defect indication FERF Far End Receive Failure -Prima denumire (in documentatia mai veche ) pentru RDI
RFC Request for Comment
Rg Remote Group
RID routing identifier - first level in the DPRS addressing hierarchy. In the DPRS, RID (Routing id), MID(module id.), MPID (module process id. ) addressing hierarchy
RIP routing information protocol
RISC reduced instruction set computer
RLB Remote Digital Loopback -modem
RM resource module
RMON Remote Monitoring
ROIReturn of Invesment - how much profit or cost saving is realized. An ROI calculation is sometimes used along with other approaches to develop a business case for a given proposal.
ROUTER
The router, like the switch, is a smart hub. However, while the switch only concerns itself with MAC addresses, the router only concerns itself with IP addresses. And it doesn’t concern itself with the individual IP address, but only the form of the IP address.If a computer within one network tried to communicate with another computer in its own network, the router would notice that the form of the destination IP address is the same as that of the network from which the message originated. So the router would not allow this packet to pass through it to the other network. It would make sure that information remained isolated within that network only. But if a computer in one network wanted to communicate with a computer in the other network, the router would allow the package to be sent into the other network. This way it allows two networks to communicate with each other, while at the same time limiting traffic to a bare minimum.
Rp relay point
RPI routing protocol interface
RS Rout selector
RSA Remote server agent
RSI Remote server interface
RSR requested shaping rate
RSVP Resource ReSerVation Protocol
RTD round trip delay
RTS Request To Send
rtVBR real-time VBR * Real time variable bit rate
SS source
SAD speech activity detection * fast <200 msec ; slow>10 sec
SAP service advertisement protocol
SAR segmentation and reassembly
SBIC shared bus interface controller
SCCS Symposium Call Center Server
SCN state change notification ( data to update the network model )
SCR source call router
SCR sustained cell rate
SDD Passport service data description
SDH Synchronous Digital Hierarchy - European Standard
SDLC Synchronous Data Link Control
SDS software distribution site
Server Farm
A group of servers usually located in a secure area, and sometimes collocated at an ISP. These servers all serve a single purpose (such as serving Web pages, for example) and have some sort of load balanced across them. If one server in the farm dies, business carries on as usual. If performance is slow, you add more servers. This term is popular when dealing with Web-based applications, where a group of web servers all serve up the same content or pull data from a database server or group of database servers.
SFPsmall form factor The Passport 1600 Routing Switch series is a fixed port Layer 3 solution set. It is available in three models: the Passport 1648T with 48 ports of 10/100 plus 4 connections for small form factor (SFP) - Small Form factor Pluggable
SFQ shaped fair queuing
SHDSL Symetric High bit-rate Digital Subscriber Line
Sig signalling
SIP
The Session Initiation Protocol (SIP) is an Internet Engineering Task Force (IETF) standard protocol for initiating an interactive user session that involves multimedia elements such as video, voice, chat, gaming, and virtual reality.Like HTTP or SMTP, SIP works in the Application layer of the Open Systems Interconnection communications model. The Application layer is the level responsible for ensuring that communication is possible. SIP can establish multimedia sessions or Internet telephony calls, and modify, or terminate them. The protocol can also invite participants to unicast or multicast sessions that do not necessarily involve the initiator.Two standards have emerged for signaling and control of VoIP telephony: ITU-T H.323 and the IETF Session Initiated Protocol (SIP). These protocols, although resulting in the same end-user service (telephony), differ in the approach to providing signaling functions. H.323 is based more on a monolithic bloc derived from H.320 for traditional of the traditional circuit-switched ISDN multimedia, and SIP favors a more lightweight approach based on HTTP.
SLC switched logical connection
SMLT Split Multi-Link Trunking
SNA systems network architecture
SNMPsimple network management protocol SNMP is the standard for network management that uses a common software agent to manage local and wide area network equipment from different vendors; part of the Transmission Control Protocol/Internet Protocol (TCP/IP) suite and defined in RFC1157. SNMPv1 is version one, or the original standard protocol. SNMPv3 is a combination of proposal updates to SNMP, most of which deal with security.
SONET Synchronous optical network -North American Standard
SP Setup priority
SPF shortest path first
Spanning Tree
Where two bridges are used to interconnect the same two computer network segments, spanning tree is a protocol that allows the bridges to exchange information so that only one of them will handle a given message that is being sent between two computers within the network. The spanning tree protocol prevents the condition known as a bridge loop.
SPO short path oriented
SPVC Soft permanent virtual circuit
SRB source route bridging is a process of relaying MAC packets along a route specified by the source end system.
SQL Structured Query Language (SQL), a programming structure that is used to process and retrieve queried information from a database.
Src Source PVC
Sres source route end station
SRT source route transparent bridging
SRTS Synchronous residual time stamp
SSH
SSH is a protocol that uses public key cryptography to transfer data securely over insecure networks. At the core of most SSH implementations are the "ssh" and "scp" commands."ssh" and "scp" are "secure" versions of the UNIX "rsh" and "rcp" commands, (which in turn are a bit like the more familiar "telnet" and "ftp" programs). The "ssh" command provides command-line, (non-GUI), access to a remote server. "scp" allows files to be copied to/from a remote server. Both programs use the SSH protocol to establish a secure connection and to encrypt all data passing between the client and the server.
SSL
The Secure Sockets Layer (SSL) is a commonly-used protocol for managing the security of a message transmission on the Internet. SSL has recently been succeeded by Transport Layer Security (TLS), which is based on SSL. SSL uses a program layer located between the Internet's Hypertext Transfer Protocol (HTTP) and Transport Control Protocol (TCP) layers. SSL is included as part of both the Microsoft and Netscape browsers and most Web server products. Developed by Netscape, SSL also gained the support of Microsoft and other Internet client/server developers as well and became the de facto standard until evolving into Transport Layer Security.
STG ID for spanning tree group
STM Synchronous Transfer Mode (mod de transport sincron European) operates with same rate as STS 3 (155.52 Mbs)
STM1 Synchronous Transport Mode; SDH standard for OC33 optical fiber at 155.52 Mbs
STP shield twisted pair- cable
STS nivelul de transport sincron -standard Nord American; compatibil SDH
SVC Switched virtual connection
SVC switched virtual circuit (Used in Voice networking)
SVPC Soft permanent virtual circuit (or connection)
SVS switched voice service
SWITCH
A switch is as a smart hub. It’s a hub that understands MAC addresses (but not IP addresses). A switch automatically learns the MAC addresses of all the computers plugged into it by communicating with them. It stores these in a little table. When it receives the packet from computer A, it reads the MAC address of the destination computer off the packet. And it proceeds to send that packet out through that port, and no other. So the packet goes only to computer C and not to computer B and D. This way the only cables being used are the ones that need to be, and the rest of the network is free to transfer other data.
TTAPI Telephony Applications Programming Interface
TCO Total Cost of Ownership
TCP transmission control protocol.
TCP-IP
Transmission control protocol/Internet protocol (TCP/IP) is a group of protocols that defines a common set of rules and standards that enable networks and hosts to communicate. IP is the routed or network layer protocol of TCP/IP and is one of the most popular internetworking protocols.TCP is responsible for breaking data down into IP packets before they are sent, and for assembling the packets when they arrive. IP is responsible for the sending and receiving data packets over the Internet.
TD-IE traffic descriptor information element
TDM Time-division-multiplexed network
TDMA TDMA (time division multiple access) is a technology used in digital cellular telephone communication that divides each cellular channel into three time slots in order to increase the amount of data that can be carried.
TDS Transparent data service
TIE (Ear & Mouth) terminal interface equipment
TIMS Transmission Impairment Measurement Set for testing &power spectrum measurement
TODA time-of-day accounting
TOP topology manager
TPT tandem pass through-tandem node detection for routing compressed voice calls through an intermediate PBX by way of tandemPassport nodes. Only MVP/MVP-E FPs support tandem pass through (TPT).
TRM transport resource manager
TRS Target shaping rate
ts time slot
UUBR unspecified bit rate
UDP user datagram protocol "Packet" and "datagram" are similar in meaning. A protocol similar to
TCP, the User Datagram Protocol (UDP) uses the term datagram. Also port for the RADIUS server.
UMTS Universal Mobile Telecommunication Service
UNACK Unacknowledged trunks
ULP upper layer protocols
UNI user network interface
UPC usage parameter control - the set of actions taken by the network to monitor and control traffic
UPS Uninterruptible Power Supply
USB Universal Serial Bus
UTC Universal Coordinated Time
UTP - universal trunk protocol- unshilded twisted pair for cable
URL Uniform Resource Locator is a pointer to a specific bit of information on the Internet.
VVBR variable bit rate
VBRrt variable bit rate real time
VBRnrt variable bit rate non real time
VC virtual circuit * Virtual channel * virtual connection . Identifica un tip de trafic, mai multe VC identifica un VP
VCC virtual channel connection-circuit * VCC is an association established between two ATM layer users that communicate through a virtual channel
Vcd virtual channel descriptor
VCI virtual channel identifier
VF voice frequency
VFF very fast forwarder
VFP Voice function processor
VLAN
Virtual LAN. Shared VLAN (SVL) and individual VLAN (IVL) learning is supported. SVL is the same as the VLAN implementation on the BayStack 450 Switch, in which all VLANs in the switch share the same forwarding database. IVL is a new feature on the Business Policy Switch and lets individual VLANs have separate forwarding databases within the switch. IVL allows the switch to handle duplicate MAC addresses if they are in different VLANs
VLSM Variable Length Subnet Masks
VNCVNC stands for Virtual Network Computing. It is, in essence, a remote display system which allows you to view a computing 'desktop' environment not only on the machine where it is running, but from anywhere on the Internet and from a wide variety of machine architectures
VNCS Voice networking call server
VNS
virtual networking system(Connectionless routing). A connectionless routing system used by Passport to transport data traffic for connectionless services The virtual networking system (VNS) routes connectionless packets across a Passport logical network. This is done by encapsulating the packets in a Passport VNS header as it enters the network and using the data in the header to route the packet across the Passport network. This allows encapsulated WAN traffic to consolidate with other Passport traffic (such as DPN and PORS traffic) on common trunks.
VoFR Voice over frame relay
VoIP
VoIP (voice over IP - that is, voice delivered using the Internet Protocol) is a term used in IP telephony for a set of facilities for managing the delivery of voice information using the Internet Protocol (IP). In general, this means sending voice information in digital form in discrete packets rather than in the traditional circuit-committed protocols of the public switched telephone network (PSTN). A major advantage of VoIP and Internet telephony is that it avoids the tolls charged by ordinary telephone service. In addition to IP, VoIP uses the real-time protocol (RTP) to help ensure that packets get delivered in a timely way. Using public networks, it is currently difficult to guarantee Quality of Service (QoS). Better service is possible with private networks managed by an enterprise or by an Internet telephony service provider (ITSP).
VP Voice profile sau Virtual Path (mai multe Virtual Channels identifica un VP)
VPC virtual path connection A VPC is an association established between two ATM layer users that communicate through a virtual PATH
Vpd virtual path descriptor
VPI virtual path indentifier/intranet
VPI ID virtual private intranet identifier
VPN Virtual Private Networks
VR virtual router
VPS Voice Processing Series
VPT Virtual path terminators- consolidates multiple VCCs into a singleVPC for ease of handling through the network backbone.
VRoute Voice route
VRRP virtual router redundancy protocol
VS Voice service
VSR (Vsr) Voice subroute
VSS Passport 15000-Variable Speed Switch
VTDS voice transparent data service
VTDS voice transparent data service
WWAN wide area network
WAP Wireless Application Protocol
WFQ Weighted fair queuing
WRED Weighted random early detection
XXDLC eXtended Digital Line Card
xDSL
xDSL x-type digital subscriber line; refers to different services of DSL, such as ADSL, HDSL, and RADSL x2/DSL is a modem from 3Com that supports 56 Kbps modem communication but is upgradeable through new software installation to ADSL when it becomes available in the user's area. 3Com calls it "the last modem you will ever need."
Y
YIA Yes- I -am If the local end does not receive a Yes I Am (YIA) packet , then the Passport trunk disables. If the local end receives a YIA packet, then the local end validates the remote node identification and continues to provide service.
Yellow alarm
DS1 also called a remote alarm or RAI , indicates a near-to-far transmission failure
Z0TLP zero transmission level point ;zero dBm transmission level point.
Z Time Zulu Time(Coordinated Universal Time) Time scale based on the second (SI) Synonyms World Time, Z Time, Zulu
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802.3
802.3 - (Ethernet) - este o retea magistrala care poate transmite date la 10Mbps. Datele sunt transmise prin fir fiecarui calculator, insa numai cele indreptatite sa le receptioneze confirma primirea. Protocolul CSMA/CD regularizeaza traficul prin retea, permitand transmisia doar atunci cand cablul este liber si nici un alt calculator nu transmite.
802.4
802.4 - (Transferul jetonului) - este o retea inel care se bazeaza pe o schema de transfer al jetonului. Fiecare calculator receptioneaza toate datele, insa raspunde numai cel a carui adresa este mentionata explicit. Jetonul care, circula pe cablu determina calculatorul care poate emite.
802.5
802.5 - (Token Ring) - este o retea inel care poate transmite date la 4 sau la 16Mbps, Chiar daca in denumire apare cuvantul inel, aceasta topologie are; forma de stea, fiecare calculator fiind conectat la un concentrator (hub) central. Inelul (inchiderea buclei) se realizeaza in cadrul concentratorului. Jetonul care circula in inel determina calculatorul care poate transmite date.