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--- networking:atm_glossary [15/01/2025 13:05] – andrew
+++ networking:atm_glossary [24/01/2025 01:50] (current) – [Jitter] andrew
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+===== 802.1d Spanning Tree Bridging =====
+ - the IEEE standard for bridging; a MAC layer standard for
+transparently connecting two or more LANs (often called subnetworks) that are running the
+same protocols and cabling. This arrangement creates an extended network, in which any two
+workstations on the linked LANs can share data.
-ForeRunner HE/200E/LE ATM Adapters for the PC User’s Manual Glossary - 19
+===== 802.3 Ethernet =====
+ - the IEEE standard for Ethernet; a physical-layer standard that uses the
+CSMA/CD access method on a bus-topology LAN.
+===== 802.5 Token Ring =====
+ - the IEEE physical-layer standard that uses the token-passing access
+method on a ring-topology LAN.
+===== AAL (ATM Adaptation Layer) =====
+ - the AAL divides the user information into segments suitable
+for packaging into a series of ATM cells. There are several types of AALs in use. FORE Sys-
+tems currently supports AAL 5 and AAL 3/4. AAL 3/4 supports connection-oriented VBR
+data transfer and connectionless VBR data transfer, respectively. AAL 5 is defined as Simple
+and Efficient Adaptation Layer (SEAL).
+===== AAL Connection =====
+ - an association established by the AAL between two or more next higher
+layer entities.
+===== ABR (Available Bit Rate) =====
+ - a type of traffic for which the ATM network attempts to meet that
+traffic's bandwidth requirements. It does not guarantee a specific amount of bandwidth and
+the end station must retransmit any information that did not reach the far end.
+ACR (Allowable Cell Rate) - parameter defined by the ATM Forum for ATM traffic manage-
+ment. ACR varies between the MCR and the PCR, and is dynamically controlled using con-
+gestion control mechanisms.
+===== Address Mask =====
+ - a bit mask used to identify which bits in an address (usually an IP address)
+are network significant, subnet significant, and host significant portions of the complete
+address. This mask is also known as the subnet mask because the subnetwork portion of the
+address can be determined by comparing the binary version of the mask to an IP address in
+that subnet. The mask holds the same number of bits as the protocol address it references.
+Agent (SNMP) - a component of network- and desktop-management software, such as SNMP,
+that gathers information from MIBs.
+===== AIS (Alarm Indication Signal) =====
+ - a line AIS is asserted when a 111 binary pattern is detected in
+bits 6, 7, 8 of the K2 byte for five consecutive frames. A line AIS is removed when any pattern
+other than 111 is detected in these bits for five consecutive frames.
+===== alarm =====
+ - an unsolicited message from a device, typically indicating a problem with the system
+that requires attention.
+===== AMI (ATM Management Interface) =====
+ - the user interface to FORE Systems’ ForeThought switch
+control software (SCS). AMI lets users monitor and change various operating configurations
+of FORE Systems switches and network module hardware and software, IP connectivity, and
+SNMP network management.
+===== ANSI (American National Standards Institute) =====
+ - a private organization that coordinates the
+setting and approval of some U.S. standards. It also represents the United States to the Inter-
+national Standards Organization.
+===== API (Application Program Interface) =====
+ - a language format that defines how a program can be
+made to interact with another program, service, or other software; it allows users to develop
+custom interfaces with FORE products.
+===== APP (application program) =====
+ - a complete, self-contained program that performs a specific
+function directly for the user.
+===== AppleTalk =====
+ - a networking protocol developed by Apple Computer for communication
+between Apple’s products and other computers. Independent of the network layer, AppleTalk
+runs on LocalTalk, EtherTalk and TokenTalk.
+===== ARP (Address Resolution Protocol) =====
+ - a method used to resolve higher level protocol
+addressing (such as IP) into the appropriate header data required for ATM; i.e., port, VPI, and
+VCI; also defines the AAL type to be used.
+===== ASCII (American Standard Code for Information Interchange) =====
+ - a standard character set that (typically) assigns a 7-bit sequence to each letter, number, and selected control characters.
+===== Assigned Cell =====
+ - a cell that provides a service to an upper layer entity or ATM Layer Manage-
+ment entity (ATMM-entity).
+===== asxmon =====
+ - a FORE program that repeatedly displays the state of the switch and of all its active
+ports.
+===== ATDM (Asynchronous Time Division Multiplexing) =====
+ - a method of sending information that
+resembles normal TDM, except that time slots are allocated as needed rather than preassigned
+to specific transmitters.
+===== ATM (Asynchronous Transfer Mode) =====
+ - a transfer mode in which the information is organized
+into cells. It is asynchronous in the sense that the recurrence of cells containing information
+from an individual user is not necessarily periodic.
+===== ATM Forum =====
+ - an international non-profit organization formed with the objective of accelerat-
+ing the use of ATM products and services through a rapid convergence of interoperability
+specifications. In addition, the Forum promotes industry cooperation and awareness.
+===== ATM Layer link =====
+ - a section of an ATM Layer connection between two adjacent active ATM
+Layer entities (ATM-entities).
+===== ATM Link =====
+ - a virtual path link (VPL) or a virtual channel link (VCL).
+===== ATM Peer-to-Peer Connection =====
+ - a virtual channel connection (VCC) or a virtual path connec-
+tion (VPC) directly established, such as workstation-to-workstation. This setup is not com-
+monly used in networks.
+===== ATM Traffic Descriptor =====
+ - a generic list of parameters that can be used to capture the intrinsic
+traffic characteristics of a requested ATM connection.
+===== ATM User-to-User Connection =====
+ - an association established by the ATM Layer to support
+communication between two or more ATM service users (i.e., between two or more next
+higher layer entities or between two or more ATM entities). The communication over an ATM
+Layer connection may be either bidirectional or unidirectional. The same Virtual Channel
+Identifier (VCI) is used for both directions of a connection at an interface.
+===== atmarp =====
+ - a FORE program that shows and manipulates ATM ARP entries maintained by the
+given device driver. This is also used to establish PVC connections.
+===== atmconfig =====
+ - a FORE program used to enable or disable SPANS signalling.
+===== atmstat =====
+ - a FORE program that shows statistics gathered about a given adapter card by the
+device driver. These statistics include ATM layer and ATM adaptation layer cell and error
+counts. This can also be used to query other hosts via SNMP.
+===== AUI (Attachment User Interface) =====
+ - IEEE 802.3 interface between a media attachment unit
+(MAU) and a network interface card (NIC). The term AUI can also refer to the rear panel port
+to which an AUI cable might attach.
+===== Auto-logout =====
+ - a feature that automatically logs out a user if there has been no user interface
+activity for a specified length of time.
+===== B8ZS (Bipolar 8 Zero Substitution) =====
+ - a line coding technique used to accommodate the ones density requirements of T1 facilities.
+===== Backbone =====
+ - the main connectivity device of a distributed system. All systems that have con-
+nectivity to the backbone connect to each other. This does not stop systems from setting up
+private arrangements with each other to bypass the backbone for cost, performance, or secu-
+rity.
+===== Bandwidth =====
+ - usually identifies the capacity or amount of data that can be sent through a given circuit; may be user-specified in a PVC.
+===== baud =====
+ - unit of signalling speed. The speed in baud is the number of discrete conditions or sig-
+nal events per second. If each signal event represents only one bit, the baud rate is the same as
+bps; if each signal event represents more than one bit (such as a dibit), the baud rate is smaller
+than bps.
+===== BECN (Backward Explicit Congestion Notification) =====
+ - bit set by a Frame Relay network in
+frames traveling in the opposite direction of frames encountering a congested path. Data ter-
+minal equipment (DTE) receiving frames with the BECN bit set can request that higher-level
+protocols take flow control action as appropriate. Compare with FECN.
+===== BES (Bursty Errored Seconds) =====
+ - a BES contains more than 1 and fewer than 320 path coding
+violation error events, and no severely errored frame or AIS defects. Controlled slips are not
+included in determining BESs.
+===== BGP (Border Gateway Protocol) =====
+ - used by gateways in an internet connecting autonomous
+networks. It is derived from experiences learned using the EGP.
+===== BIP (Bit Interleaved Parity) =====
+ - an error-detection technique in which character bit patterns are
+forced into parity, so that the total number of one bits is always odd or always even. This is
+accomplished by the addition of a one or zero bit to each byte, as the byte is transmitted; at the
+other end of the transmission, the receiving device verifies the parity (odd or even) and the
+accuracy of the transmission.
+===== B-ISDN (Broadband Integrated Services Digital Network) =====
+ - a common digital network suitable for voice, video, and high-speed data services running at rates beginning at 155 Mbps.
+===== BNC (Bayonet-Neill-Concelman) =====
+ - a bayonet-locking connector for miniature coax.
+===== BPDU (Bridged Protocol Data Unit) =====
+ - Spanning-tree Protocol hello packet that is sent out at
+configurable intervals to exchange information among bridges in the network.
+===== bps (bits per second) =====
+ - a measure of speed or data rate. Often combined with metric prefixes
+in kbps for thousands of bits per second (k fir kilo-) and in Mbps for millions of bits per sec-
+ond (M for mega-).
+===== BPV (Bipolar Violation) =====
+ - an error event on a line in which the normal pattern of alternating
+high (one) and low (zero) signals is disrupted. A bipolar violation is noted when two high sig-
+nals occur without an intervening low signal, or vice versa.
+===== Bridge =====
+ - a device that expands a Local Area Network by forwarding frames between data link
+layers associated with two separate cables, usually carrying a common protocol. Bridges can
+usually be made to filter certain packets (to forward only certain traffic).
+===== Broadband =====
+ - a service or system requiring transmission channels capable of supporting rates
+greater than the Integrated Services Digital Network (ISDN) primary rate.
+===== Broadband Access =====
+ - an ISDN access capable of supporting one or more broadband services.
+Brouter (bridging/router) - a device that routes some protocols and bridges others based on
+configuration information.
+===== Bursty Second =====
+ - a second during which there were at least the set number of BES threshold
+event errors but fewer than the set number of SES threshold event errors.
+===== BUS (Broadcast and Unknown Server) =====
+ - in an emulated LAN, the BUS is responsible for accepting broadcast, multicast, and unknown unicast packets from the LECs to the broadcast MAC address (FFFFFFFFFFFF) via dedicated point-to-point connections, and forwarding the
+packets to all of the members of the ELAN using a single point-to-multipoint connection.
+===== CAC (Connection Admission Control) =====
+ - the procedure used to decide if a request for an
+ATM connection can be accepted based on the attributes of both the requested connection and
+the existing connections.
+===== Call =====
+ - an association between two or more users or between a user and a network entity that is
+established by the use of network capabilities. This association may have zero or more connec-
+tions.
+===== Carrier =====
+ - a company, such as any of the “baby Bell” companies, that provide network communications services, either within a local area or between local areas.
+===== CBR (Constant Bit Rate) =====
+ - a type of traffic that requires a continuous, specific amount of
+bandwidth over the ATM network (e.g., digital information such as video and digitized
+voice).
+===== CBR port =====
+ - a port on the CellPath 300 for transmitting and receiving CBR traffic.
+cchan - a FORE program used to manage virtual channels on a FORE Systems ATM switch
+running asxd.
+===== CCITT (Consultative Committee for International Telephone and Telegraph) =====
+ - an international consultative committee that sets international communications recommendations,
+which are frequently adopted as standards; develops interface, modem, and data network recommendations. Membership includes PTTs, scientific and trade associations, and private companies. CCITT is part of the International Communications Union (a United nations treaty organization in Geneva).
+===== CDV (Cell Delay Variation) =====
+ - a quantification of cell clumping for a connection. The cell
+clumping CDV (yk) is defined as the difference between a cell’s expected reference arrival
+time (ck) and its actual arrival time (ak). The expected reference arrival time (ck) of cell k of a
+specific connection is max . T is the reciprocal of the negotiated peak cell rate.
+===== CE (Connection Endpoint) =====
+ - a terminator at one end of a layer connection within a SAP.
+===== CEI (Connection Endpoint Identifier) =====
+ - an identifier of a CE that can be used to identify the
+connection at a SAP.
+===== Cell =====
+ - an ATM Layer protocol data unit (PDU). The basic unit of information transported in
+ATM technology, each 53-byte cell contains a 5-byte header and a 48-byte payload.
+===== Cell Delineation =====
+ - the protocol for recognizing the beginning and end of ATM cells within the
+raw serial bit stream.
+===== Cell Header =====
+ - ATM Layer protocol control information.
+===== Cell Port =====
+ - a port on the CellPath 300 that transmits and receives traffic in cell format.
+===== Cell Rate Adaptation =====
+ - a function performed by a protocol module in which empty cells
+(known as unassigned cells) are added to the output stream. This is because there always must
+be a fixed number of cells in the output direction; when there are not enough cells to transmit,
+unassigned cells are added to the output data stream.
+===== Cell Transfer Delay =====
+ - the transit delay of an ATM cell successfully passed between two desig-
+nated boundaries.
+===== CES (Circuit emulation Services) =====
+ - The CellPath 90 supports Circuit Emulation Services
+(CES) for applications requiring a fixed delay, lossless end-to-end connection through the net-
+work. In essence, CES provides a virtual private line service to the connecting application.
+Channelization - capability of transmitting independent signals together over a cable while
+still maintaining their separate identity for later separation.
+===== CLP (Cell Loss Priority) =====
+ - the last bit of byte four in an ATM cell header; indicates the eligibil-
+ity of the cell for discard by the network under congested conditions. If the bit is set to 1, the
+cell may be discarded by the network depending on traffic conditions.
+===== Cold Start Trap =====
+ - a CellPath 300 SNMP trap which is sent when the unit has been power-
+cycled (see trap).
+===== Comm Port =====
+ - the front panel DCE port that allows access to the CellPath 300 user interface via
+a connected terminal.
+===== Concentrator =====
+ - a communications device that offers the ability to concentrate many lower-
+speed channels into and out of one or more high-speed channels.
+===== Congestion Management =====
+ - a CellPath 300 feature that helps ensure reasonable service for
+VBR connections in an ATM network. For each connection, the CellPath 300 maintains a prior-
+ity, sustained cell rate (SCR), and peak cell rate (PCR). During times of congestion, the CellPath
+reduces the bandwidth to the SCR, based on the priority of the connection.
+===== Connection =====
+ - the concatenation of ATM Layer links in order to provide an end-to-end infor-
+mation transfer capability to access points.
+===== Connectionless Service =====
+ - a type of service in which no pre-determined path or link has been
+established for transfer of information, supported by AAL 4.
+===== Connection-Oriented Service =====
+ - a type of service in which information always traverses the
+same pre-established path or link between two points, supported by AAL 3.
+===== Controlled Slip =====
+ - a situation in which one frame’s worth of data is either lost or replicated. A
+controlled slip typically occurs when the sending device and receiving device are not using
+the same clock.
+===== Corresponding Entities =====
+ - peer entities with a lower layer connection among them
+===== cpath =====
+ - a FORE program used to manage virtual paths on a FORE Systems ATM switch running asxd.
+===== CPE (Customer Premise Equipment) =====
+ - equipment that is on the customer side of the point of
+demarcation, as opposed to equipment that is on a carrier side. See also point of demarcation.
+cport - a FORE program used to monitor and change the state of ports on a FORE Systems
+ATM switch running asxd.
+===== CRC (Cyclic Redundancy Check) =====
+ - an error detection scheme in which a number is derived
+from the data that will be transmitted. By recalculating the CRC at the remote end and com-
+paring it to the value originally transmitted, the receiving node can detect errors.
+Cross Connection - a mapping between two channels or paths at a network device such as
+the CellPath 300.
+===== CD (Controlled Slip) =====
+ - a situation in which one frame’s worth of data is either lost or repli-
+cated. A controlled slip typically occurs when the sending device and receiving device are not
+using the same clock.
+===== CS (Convergence Sublayer) =====
+ - a portion of the AAL. Data is passed first to the CS where it is
+divided into rational, fixed-length packets or PDUs (Protocol Data Units). For example, AAL 4
+processes user data into blocks that are a maximum of 64 kbytes long.
+CTS (Clear To Send) - and RS-232 modem interface control signal (sent from the modem to
+the DTE on pin 5) which indicates that the attached DTE may begin transmitting; issuance in
+response to the DTE’s RTS.
+===== D4 framing =====
+ - See SF)
+===== DARPA (Defense Advanced Research Projects Agency) =====
+ - the US government agency that funded the ARPANET.
+===== Datagram =====
+ - a packet of information used in a connectionless network service that is routed to
+its destination using an address included in the datagram’s header.
+DCE (Data Communications Equipment) - a definition in the RS232C standard that
+describes the functions of the signals and the physical characteristics of an interface for a com-
+munication device such as a modem.
+===== DCS (Digital Cross-connect System) =====
+ - an electronic patch panel used to route digital signals in a central office.
+===== Demultiplexing =====
+ - a function performed by a layer entity that identifies and separates SDUs
+from a single connection to more than one connection (see multiplexing).
+DFA (DXI Frame Address) - a connection identifier associated with ATM DXI packets that
+serves the same functions as, and translates directly to, the VPI/VCI on an ATM cell.
+===== DIP Switch (Dual In-line Package) =====
+ - a device that has two parallel rows of contacts that let
+the user switch electrical current through a pair of those contacts to on or off. They are used to
+reconfigure components and peripherals.
+DLCI (Data Link Connection Identifier) - a connection identifier associated with frame relay
+packets that serves the same functions as, and translates directly to, the VPI/VCI on an ATM cell.
+===== Domain Name Server =====
+ - a computer that converts names to their corresponding Internet num-
+bers. It allows users to telnet or FTP to the name instead of the number.
+===== DNS (Domain Name System) =====
+ - the distributed name and address mechanism used in the Internet.
+===== DSn (Digital Standard n (0, 1, 1C, 2, and 3)) =====
+ - a method defining the rate and format of digital hierarchy, with asynchronous data rates defined as follows:
+  - DS0 64kbps 1 voice channel
+  - DS1 1.544Mbps 24 DS0s
+  - DS1C 3.152 Mbps 2 DS1s
+  - DS2 6.312 Mbps 4 DS1s
+  - DS3 44.736 Mbps 28 DS1s
+    Synchronous data rates (SONET) are defined as:
+  - STS-1/OC-1 51.84 Mbps 28 DS1s or 1 DS3
+  - STS-3/OC-3 155.52 Mbps 3 STS-1s byte interleaved
+  - STS-3c/OC-3c 155.52 Mbps Concatenated, indivisible payload
+  - STS-12/OC-12 622.08 Mbps 12 STS-1s, 4 STS-3cs, or any mixture
+  - STS-12c/OC-12c 622.08 Mbps Concatenated, indivisible payload
+  - STS-48/OC-48 2488.32 Mbps 48 STS-1s, 16 STS-3cs, or any mixture
+===== DSR (Data Set Ready) =====
+ - an RS-232 modem interface control signal (sent from the modem to
+the DTE on pin 6) which indicates that the modem is connected to the telephone circuit. Usually a prerequisite to the DTE issuing RTS.
+===== DTE (Data Terminal Equipment) =====
+ - generally user devices, such as terminals and computers,
+that connect to data circuit-terminating equipment. They either generate or receive the data
+carried by the network.
+===== DTR (Data Terminal Ready) =====
+ - an RS232 modem interface control signal (sent from the DTE to
+the modem on pin 20) which indicates that the DTE is ready for data transmission and which
+requests that the modem be connected to the telephone circuit.
+===== DXI =====
+ - a generic phrase used in the full names of several protocols, all commonly used to allow
+a pair of DCE and DTE devices to share the implementation of a particular WAN protocol. The
+protocols all define the packet formats used to transport data packets between DCE and DTE
+devices.
+===== E1 =====
+ - Wide-area digital transmission scheme used predominantly in Europe that carries data at
+a rate of 2.048 Mbps. E1 lines can be leased for private use from common carriers.
+===== E3 =====
+ - Wide-area digital transmission scheme used predominantly in Europe that carries data at
+a rate of 34.368 Mbps. E3 lines can be leased for private use from common carriers.
+===== EEPROM (Electrically Erasable Programmable Read Only Memory) =====
+ - an EPROM that can be cleared with electrical signals rather than the traditional ultraviolet light.
+===== EFCI (Explicit Forward Congestion Indication) =====
+ - the second bit of the payload type field in the header of an ATM cell, the EFCI bit indicates network congestion to receiving hosts. On a congested switch, the EFCI bit is set to “1” by the transmitting network module when a certain number of cells have accumulated in the network module’s shared memory buffer. When a cell is received that has its EFCI bit set to “1,” the receiving host notifies the sending host, which should then reduce its transmission rate.
+===== EGP (Exterior Gateway) Protocol =====
+ - used by gateways in an internet, connecting autonomous networks.
+===== EIA (Electronics Industries Association) =====
+ - a USA trade organization that issues its own
+standards and contributes to ANSI; developed RS-232. Membership includes USA manufac-
+turers.
+===== EISA (Extended Industry Standard Architecture) =====
+ - a bus architecture for desktop computers
+that provides a 32-bit data passage while maintaining compatibility with the ISA or AT archi-
+tecture.
+===== elarp =====
+ - a FORE program that shows and manipulates MAC and ATM address mappings for LAN Emulation Clients (LECs).
+===== elconfig =====
+ - a FORE program that shows and modifies LEC configuration. Allows the user to set
+the NSAP address of the LAN Emulation Configuration Server (LECS), display the list of
+Emulated LANs (ELANs) configured in the LECS for this host, display the list of ELANs
+locally configured along with the membership state of each, and locally administer ELAN
+membership.
+===== EM =====
+ - the CellPath 300 extension module; paired with the system controller and supporting an
+optional PCMCIA card.
+===== Embedded SNMP Agent =====
+ - an SNMP agent can come in two forms: embedded or proxy. An
+embedded SNMP agent is integrated into the physical hardware and software of the unit. The
+CellPath 300 has an internal, integrated SNMP agent.
+===== EMI (Electromagnetic Interference) =====
+ - signals generated and radiated by an electronic device
+that cause interference with radio communications, among other effects.
+End-to-End Connection - when used in reference to an ATM network, a connection that trav-
+els through an ATM network, passing through various ATM devices and with endpoints at the
+termination of the ATM network.
+===== EPROM =====
+ - Erasable Programmable Read Only Memory (see PROM).
+===== EQL (Equalization) =====
+ - the process of compensating for line distortions.
+===== ES (End System) =====
+ - a system in which an ATM connection is terminated or initiated. An origi-
+nating end system initiates the ATM connection, and a terminating end system terminates the
+ATM connection. OAM cells may be generated and received.
+===== ES (Errored Seconds) =====
+ - a second during which at least one code violation occurred.
+===== ESF (Extended Superframe) =====
+ - T1 framing standard that provides frame synchronization, cyclic redundancy, and data link bits.
+===== Ethernet =====
+ - a 10-Mbps, coaxial standard for LANs in which all nodes connect to the cable
+where they contend for access.
+===== Fairness =====
+ - as related to Generic Flow Control (GFC), fairness is defined as meeting all of the
+agreed quality of service (QoS) requirements by controlling the order of service for all active
+connections.
+===== Far-End =====
+ - in a relationship between two devices in a circuit, the far-end device is the one that
+is remote.
+===== FCC =====
+ - a board of commissioners appointed by the President under the Communications Act of
+, with the authority to regulate all interstate telecommunications originating in the United
+States, including transmission over phone lines.
+===== FDDI (Fiber Distributed Data Interface) =====
+ - high-speed data network that uses fiber-optic as
+the physical medium. Operates in similar manner to Ethernet or Token Ring, only faster.
+===== FDM (Frequency Division Multiplexing) =====
+ - a method of dividing an available frequency range
+into parts with each having enough bandwidth to carry one channel.
+===== FEBE (Far End Block Error) =====
+ - an error detected by extracting the 4-bit FEBE field from the
+path status byte (G1). The legal range for the 4-bit field is between 0000 and 1000, representing
+zero to eight errors. Any other value is interpreted as zero errors.
+===== FECN (Forward Explicit Congestion Notification) =====
+ - bit set by a Frame Relay network to
+inform data terminal equipment (DTE) receiving the frame that congestion was experienced in
+the path from source to destination. DTE receiving frames with the FECN bit set can request
+that higher-level protocols take flow control action as appropriate. Compare with BECN.
+===== FERF (Far End Receive Failure) =====
+ - a line error asserted when a 110 binary pattern is detected
+in bits 6, 7, 8 of the K2 byte for five consecutive frames. A line FERF is removed when any pattern other than 110 is detected in these bits for five consecutive frames.
+===== FIFO (First-In, First-Out) =====
+ - a method of coordinating the sequential flow of data through a buffer.
+===== Flag =====
+ - a specific bit pattern used to identify the beginning or end of a frame.
+Frame - a variable length group of data bits with a specific format containing flags at the
+beginning and end to provide demarcation.
+===== Frame Relay =====
+ - a fast packet switching protocol based on the LAPD protocol of ISDN that per-
+forms routing and transfer with less overhead processing than X.25.
+===== Frame Synchronization Error =====
+ - an error in which one or more time slot framing bits are in
+error.
+===== Framing =====
+ - a protocol that separates incoming bits into identifiable groups so that the receiving
+multiplexer recognizes the grouping.
+===== FT-PNNI (ForeThought PNNI) =====
+ - a FORE Systems routing and signalling protocol that uses private ATM (NSAP) addresses; a precursor to ATM Forum PNNI (see PNNI).
+===== FTP (File Transfer Protocol) =====
+ - a TCP/IP protocol that lets a user on one computer access, and
+transfer data to and from, another computer over a network. ftp is usually the name of the
+program the user invokes to accomplish this task.
+===== GCRA (Generic Cell Rate Algorithm) =====
+ - an algorithm which is employed in traffic policing
+and is part of the user/network service contract. The GCRA is a scheduling algorithm which
+ensures that cells are marked as conforming when they arrive when expected or later than
+expected and non-conforming when they arrive sooner than expected.
+===== GFC (Generic Flow Control) =====
+ - the first four bits of the first byte in an ATM cell header. Used
+to control the flow of traffic across the User-to-Network Interface (UNI), and thus into the net-
+work. Exact mechanisms for flow control are still under investigation and no explicit defini-
+tion for this field exists at this time. (This field is used only at the UNI; for NNI-NNI use
+(between network nodes), these four bits provide additional network address capacity, and
+are appended to the VPI field.)
+===== GIO =====
+ - a proprietary bus architecture used in certain Silicon Graphics, Inc. workstations.
+===== Header =====
+ - protocol control information located at the beginning of a protocol data unit.
+===== HDB3 (High Density Bipolar) =====
+ - line-code type standard for T1 where each block of three zeros
+is replaced by 00V or B0V, where B represents an inserted pulse conforming to the AMI rule
+(ITU-T G.701, item 9004) and V represents an AMI violation (ITU-T G.701, item 9007). The
+choice of 00V or B0V is made so that the number of B pulses between consecutive V pulses is
+odd (successive V pulses are of alternate polarity so that no d.c. component is introduced).
+Compare with AMI.
+===== HDLC (High-Level Data Link Control) =====
+ - Bit-oriented synchronous data link layer protocol
+developed by the ISO. Derived from SDLC, HDLC specifies a data encapsulation method on
+synchronous serial links using frame characters and checksums. See also SDLC.
+===== HEC (Header Error Control) =====
+ - a CRC code located in the last byte of an ATM cell header that
+is used for checking cell integrity only.
+===== HIPPI (High Performance Parallel Interface) =====
+ - ANSI standard that extends the computer bus
+over fairly short distances at speeds of 800 and 1600 Mbps.
+===== HPUX =====
+ - the Hewlett-Packard version of UNIX.
+===== HSSI (High-Speed Serial Interface) =====
+ - a serial communications connection that operates at
+speeds of up to 1.544 Mbps.
+===== Hub =====
+ - a device that connects several other devices, usually in a star topology.
+===== I/O Module =====
+ - FORE’s interface cards for the LAX-20 LAN Access Switch, designed to connect
+Ethernet, Token Ring, and FDDI LANs to ForeRunner ATM networks.
+===== ICMP (Internet Control Message Protocol) =====
+ - the protocol that handles errors and control
+messages at the IP layer. ICMP is actually a part of the IP protocol layer. It can generate error
+messages, test packets, and informational messages related to IP.
+===== IEEE (Institute of Electrical and Electronics Engineers) =====
+ - the world’s largest technical pro-
+fessional society. Based in the U.S., the IEEE sponsors technical conferences, symposia & local
+meetings worldwide, publishes nearly 25% of the world’s technical papers in electrical, elec-
+tronics & computer engineering, provides educational programs for members, and promotes
+standardization.
+IETF (Internet Engineering Task Force) - a large, open, international community of network
+designers, operators, vendors and researchers whose purpose is to coordinate the operation,
+management and evolution of the Internet to resolve short- and mid-range protocol and architectural issues.
+===== ILMI (Interim Local Management Interface) =====
+ - the standard that specifies the use of the Simple Network Management Protocol (SNMP) and an ATM management information base (MIB) to provide network status and configuration information.
+===== Interface Data =====
+ - the unit of information transferred to/from the upper layer in a single inter-
+action across a SAP. Each Interface Data Unit (IDU) controls interface information and may
+also contain the whole or part of the SDU.
+===== internet =====
+ - while an internet is a network, the term “internet” is usually used to refer to a collec-
+tion of networks interconnected with routers.
+===== Internet =====
+ - (note the capital “**I**”) the largest internet in the world including large national back-
+bone nets and many regional and local networks worldwide. The Internet uses the TCP/IP
+suite. Networks with only e-mail connectivity are not considered on the Internet.
+===== Internet Addresses =====
+ - the numbers used to identify hosts on an internet network.
+Internet host numbers are divided into two parts; the first is the network number and the second, or local,
+part is a host number on that particular network. There are also three classes of networks in
+the Internet, based on the number of hosts on a given network. Large networks are classified
+as Class A, having addresses in the range 1-126 and having a maximum of 16,387,064 hosts.
+Medium networks are classified as Class B, with addresses in the range 128-191 and with a
+maximum of 64,516 hosts. Small networks are classified as Class C, having addresses in the
+range 192-254 with a maximum of 254 hosts. Addresses are given as dotted decimal numbers
+in the following format:
+nnn.nnn.nnn.nnn
+In a Class A network, the first of the numbers is the network number, the last three numbers
+are the local host address.
+In a Class B network, the first two numbers are the network, the last two are the local host
+address.
+In a Class C network, the first three numbers are the network address, the last number is the
+local host address.
+The following table summarizes the classes and sizes:
+^ Class ^ First ^ # Max# Hosts^
+| A | 1-126 16,387,064|
+| B | 129-191 64,516|
+| C | 192-223 254|
+Network mask values are used to identify the network portion and the host portion of the
+address. For:
+  - Class A - the default mask is 255.0.0.0
+  - Class B - the default mask is 255.255.0.0
+  - Class C - the default mask is 255.255.255.0
+Subnet masking is used when a portion of the host ID is used to identify a subnetwork. For
+example, if a portion of a Class B network address is used for a subnetwork, the mask could be
+set as 255.255.255.0. This would allow the third byte to be used as a subnetwork address. All
+hosts on the network would still use the IP address to get on the Internet.
+IP (Internet Protocol) - a connectionless, best-effort packet switching protocol that offers a
+common layer over dissimilar networks.
+IP Address - a unique 32-bit integer used to identify a device in an IP network. You will most
+commonly see IP addresses written in “dot” notation; for instance, 192.228.32.14 (see IP net-
+mask).
+===== IP Netmask =====
+ - a pattern of 32 bits that is combined with an IP address to determine which bits
+of an IP address denote the network number and which denote the host number. Netmasks
+are useful for sub-dividing IP networks. IP netmasks are written in “dot” notation; for
+instance, 255.255.255.0 (see IP address).
+===== IPX Protocol =====
+ (Internetwork Packet Exchange) - a NetWare protocol similar to the Xerox
+Network Systems (XNS) protocol that provides datagram delivery of messages.
+===== IS (Intermediate system) =====
+ - a system that provides forwarding functions or relaying functions
+or both for a specific ATM connection. OAM cells may be generated and received.
+===== ISA Bus =====
+ - a bus standard developed by IBM for expansion cards in the first IBM PC. The orig-
+inal bus supported a data path only 8 bits wide. IBM subsequently developed a 16-bit version
+for its AT class computers. The 16-bit AT ISA bus supports both 8- and 16-bit cards. The 8-bit
+bus is commonly called the PC/XT bus, and the 16-bit bus is called the AT bus.
+===== ISDN (Integrated Services Digital Network) =====
+ - an emerging technology that is beginning to be
+offered by the telephone carriers of the world. ISDN combines voice and digital network ser-
+vices into a single medium or wire.
+===== ISO (International Standards Organization) =====
+ - a voluntary, non treaty organization founded
+in 1946 that is responsible for creating international standards in many areas, including com-
+puters and communications.
+===== Isochronous =====
+ - signals carrying embedded timing information or signals that are dependent
+on uniform timing; usually associated with voice and/or video transmission.
+===== ITU (International Telecommunications Union) =====
+ - the telecommunications agency of the
+United Nations, established to provide standardized communications procedures and practices, including frequency allocation and radio regulations, on a worldwide basis.
+===== J2 =====
+ - Wide-area digital transmission scheme used predominantly in Japan that carries data at a
+rate of 6.312 Mbps.
+===== Jitter =====
+ - analog communication line distortion caused by variations of a signal from its refer-
+ence timing position.
+===== Jumper =====
+ - a patch cable or wire used to establish a circuit, often temporarily, for testing or diag-
+nostics; also, the devices, shorting blocks, used to connect adjacent exposed pins on a printed
+circuit board that control the functionality of the card.
+===== LAN (Local Area Network) =====
+ - a data network intended to serve an area of only a few square
+kilometers or less. Because the network is known to cover only a small area, optimizations can
+be made in the network signal protocols that permit higher data rates.
+===== lane =====
+ - a program that provides control over the execution of the LAN Emulation Server (LES),
+Broadcast/Unknown Server (BUS), and LAN Emulation Configuration Server (LECS) on the
+local host.
+===== LAN Access Concentrator =====
+ - a LAN access device that allows a shared transmission medium
+to accommodate more data sources than there are channels currently available within the
+transmission medium.
+===== LAPB =====
+ (Link Access Procedure, Balanced) - Data link protocol in the X.25 protocol stack.
+LAPB is a bit-oriented protocol derived from HDLC. See also HDLC and X.25.
+===== LAX-20 =====
+ - a FORE Systems LAN Access Switch, designed to connect Ethernet, Token Ring, and
+FDDI LANs to ForeRunner ATM networks. The LAX-20 is a multiport, multiprotocol internet-
+working switch that combines the advantages of a high-performance LAN switch and a full-
+featured ATM interface capable of carrying LAN traffic.
+===== Layer Entity =====
+ - an active layer within an element.
+===== Layer Function =====
+ - a part of the activity of the layer entities.
+===== Layer Service =====
+ - a capability of a layer and the layers beneath it that is provided to the upper
+layer entities at the boundary between that layer and the next higher layer.
+===== Layer User Data =====
+ - the information transferred between corresponding entities on behalf of the
+upper layer or layer management entities for which they are providing services.
+===== le =====
+ - a FORE program that implements both the LAN Emulation Server (LES) and the Broad-
+cast/Unknown Server (BUS).
+===== LEC (LAN Emulation Client) =====
+ - the component in an end system that performs data forwarding, address resolution, and other control functions when communicating with other components within an ELAN.
+===== lecs =====
+ - a FORE program that implements the assignment of individual LECs to different emulated LANs.
+===== LECS (LAN Emulation Configuration Server) =====
+ - the LECS is responsible for the initial configuration of LECs. It provides information about available ELANs that a LEC may join, together with the addresses of the LES and BUS associated with each ELAN.
+===== leq =====
+ - a FORE program that provides information about an ELAN. This information is obtained
+from the LES, and includes MAC addresses registered on the ELAN together with their corre-
+sponding ATM addresses.
+===== LES (LAN Emulation Server) =====
+ - the LES implements the control coordination function for an
+ELAN. The LES provides the service of registering and resolving MAC addresses to ATM
+addresses.
+Link Down Trap - a CellPath 300 SNMP trap that signifies that the Ethernet interface has tran-
+sitioned from a normal state to an error state, or has been disconnected.
+Link Up Trap - a CellPath 300 SNMP trap that signifies that the Ethernet interface has transi-
+tioned from an error condition to a normal state.
+Glossary - 16
+ForeRunner HE/200E/LE ATM Adapters for the PC User’s Manual
 Glossary
+LLC (Logical Link Control) - a protocol developed by the IEEE 802 committee for data-link-
+layer transmission control; the upper sublayer of the IEEE Layer 2 (OSI) protocol that comple-
+ments the MAC protocol; IEEE standard 802.2; includes end-system addressing and error
+checking.
+LOF (Loss Of Frame) - a type of transmission error that may occur in wide-area carrier lines.
+Loopback - a troubleshooting technique that returns a transmitted signal to its source so that
+the signal can be analyzed for errors. Typically, a loopback is set at various points in a line
+until the section of the line that is causing the problem is discovered.
+looptest - a program that tests the interface for basic cell reception and transmission function-
+ality. It is usually used for diagnostic purposes to determine if an interface is functioning prop-
+erly.
+LOP (Loss Of Pointer) - a type of transmission error that may occur in wide-area carrier lines.
+LOS (Loss Of Signal) - a type of transmission error that may occur in wide-area carrier lines.
+MAC (Media Access Control) - a media-specific access control protocol within IEEE 802 spec-
+ifications; currently includes variations for Token Ring, token bus, and CSMA/CD; the lower
+sublayer of the IEEE's link layer (OSI), which complements the Logical Link Control (LLC).
+MAU (Media Attachment Unit) - device used in Ethernet and IEEE 802.3 networks that pro-
+vides the interface between the AUI port of a station and the common medium of the Ether-
+net. The MAU, which can be built into a station or can be a separate device, performs physical
+layer functions including conversion of the digital data from the Ethernet interface, collision
+detection, and injection of bits onto the network.
+Maximum Burst Tolerance - the largest burst of data that a network device is guaranteed to
+handle without discarding cells or packets. Bursts of data larger than the maximum burst size
+may be subject to discard.
+MCR (Minimum Cell Rate) - parameter defined by the ATM Forum for ATM traffic manage-
+ment. MCR is defined only for ABR transmissions, and specifies the minimum value for the
+ACR.
+Metasignalling - an ATM Layer Management (LM) process that manages different types of
+signalling and possibly semipermanent virtual channels (VCs), including the assignment,
+removal, and checking of VCs.
+Metasignalling VCs - the standardized VCs that convey metasignalling information across a
+User-to-Network Interface (UNI).
+MIB (Management Information Base) - the set of parameters that an SNMP management sta-
+tion can query or set in the SNMP agent of a networked device (e.g., router).
+MIC (Media Interface Connector) - the optical fiber connector that joins the fiber to the FDDI
+controller.
+ForeRunner HE/200E/LE ATM Adapters for the PC User’s Manual Glossary - 17
 Glossary
+Glossary
+MicroChannel - a proprietary 16- or 32-bit bus developed by IBM for its PS/2 computers’
+internal expansion cards; also offered by others.
+MTU (Maximum Transmission Unit) - the largest unit of data that can be sent over a type of
+physical medium.
+Multi-homed - a device that has both an ATM and another network connection, typically
+Ethernet.
+Multiplexing - a function within a layer that interleaves the information from multiple con-
+nections into one connection (see demultiplexing).
+Multipoint Access - user access in which more than one terminal equipment (TE) is sup-
+ported by a single network termination.
+Multipoint-to-Point Connection - a Point-to-Multipoint Connection may have zero band-
+width from the Root Node to the Leaf Nodes, and non-zero return bandwidth from the Leaf
+Nodes to the Root Node. Such a connection is also known as a Multipoint-to-Point Connec-
+tion.
+Multipoint-to-Multipoint Connection - a collection of associated ATM VC or VP links, and
+their associated endpoint nodes, with the following properties:
+. All N nodes in the connection, called Endpoints, serve as a Root Node in a Point-to-Multi-
+point connection to all of the (N-1) remaining endpoints.
+. Each of the endpoints can send information directly to any other endpoint, but the receiving
+endpoint cannot distinguish which of the endpoints is sending information without addi-
+tional (e.g., higher layer) information.
+Near-End - in a relationship between two devices in a circuit, the near-end device is the one
+that is local.
+Network Module - ATM port interface cards which may be individually added or removed
+from any ForeRunner ATM switch to provide a diverse choice of connection alternatives. Each
+network module provides between one and six full-duplex ATM physical connections to the
+ForeRunner switch.
+NMS (Network Management Station) - the system responsible for managing a network or a
+portion of a network. The NMS talks to network management agents, which reside in the
+managed nodes.
+NNI (Network-to-Network Interface or Network Node Interface) - the interface between two
+public network pieces of equipment.
+nonvolatile - a term used to describe a data storage device (memory) that retains its contents
+when power is lost.
+Glossary - 18
+ForeRunner HE/200E/LE ATM Adapters for the PC User’s Manual
+Glossary
+NuBus - a high-speed bus used in the Macintosh family of computers, structured so that users
+can put a card into any slot on the board without creating conflict over the priority between
+those cards
+OAM (Operation and Maintenance) Cell - a cell that contains ATM LM information. It does
+not form part of the upper layer information transfer.
+octet - a grouping of 8 bits; similar, but not identical, to a byte.
+OID (Object Identifier) - the address of a MIB variable.
+OOF (Out-of-Frame) - a signal condition and alarm in which some or all framing bits are lost.
+OpenView - Hewlett-Packard’s network management software.
+OSI (Open Systems Interconnection) - the 7-layer suite of protocols designed by ISO com-
+mittees to be the international standard computer network architecture.
+OSPF (Open Shortest Path First) Protocol - a routing algorithm for IP that incorporates
+least-cost, equal-cost, and load balancing.
+Out-of-Band Management - refers to switch configuration via the serial port or over Ether-
+net, not ATM.
+packet - a group of bits - including information bits and overhead bits - transmitted as a com-
+plete package on a network. Usually smaller than a transmission block.
+Packet Port - a port on the CellPath 300 that transmits and receives packet traffic.
+Packet Switching - a communications paradigm in which packets (messages) are individu-
+ally routed between hosts with no previously established communications path.
+Payload Scrambling - a technique that eliminates certain bit patterns that may occur within
+an ATM cell payload that could be misinterpreted by certain sensitive transmission equipment
+as an alarm condition.
+PBX (Private Branch Exchange) - a private phone system (switch) that connects to the pub-
+lic telephone network and offers in-house connectivity. To reach an outside line, the user must
+dial a digit like 8 or 9.
+PCI (Peripheral Component Interconnect) - a local-bus standard created by Intel.
+PCM (Pulse Code Modulation) - a modulation scheme that samples the information signals
+and transmits a series of coded pulses to represent the data.
+PCR (Peak Cell Rate) - parameter defined by the ATM Forum for ATM traffic management.
+In CBR transmissions, PCR determines how often data samples are sent. In ABR transmis-
+sions, PCR determines the maximum value of the ACR.
+PDN (Public Data Network) - a network designed primarily for data transmission and
+intended for sharing by many users from many organizations.
 PDU (Protocol Data Unit) - a unit of data specified in a layer protocol and consisting of proto-
 col control information and layer user data.