Source address. An address in a network frame that designates the source of the packet it is carrying.
Set Asynchronous Balanced Mode.
Set asynchronous balanced mode extended. A logical link control (LLC) command protocol data unit (PDU) used to establish a link. The SABME command PDU establishes an LLC2 (numbered and acknowledged) connection to the destination LLC that operates in asynchronous balanced mode.
Single-attached concentrator. A hub that offers a single attachment to the FDDI network, usually to the primary ring.
Service access point. The point at which the services of a protocol layer are made available to the next higher layer. Each service access point has a SAP address, by which the particular entity that is employing a layer service can be differentiated from all other entities that might also be able to use that layer service.
Service Advertising Protocol (in IPX). A Novell protocol that provides a means for servers to advertise their services to routers and other servers.
Segmentation and reassembly. In ATM, a sublayer of AAL; a process performed on ATM information cells.
Single-attached (concentrator) station. A station that has a single attachment to the FDDI network, usually to the primary ring.
The ability of many Bay Networks products to save and restore network management and host module configurations after a power cycle or the hot-swap of a unit.
Square/subscriber connector. A square-ended connector for fiber optic cable. See also ST connector.
The ability to grow and adjust network hardware and software resources according to user demand for communication services.
Serial communication controller.
Small Computer System Interface. ANSI-defined high-speed parallel interface that uses one computer port to connect to peripheral devices in a daisy-chained configuration.
Start delimiter. Single byte that marks the beginning of a token ring frame.
Shielded twisted pair (STP) FDDI. Early, proprietary schemes for running 100 Mb/s FDDI over twisted pair wiring. SDDI was replaced by the FDDI TP-PMD standard. See also TP-PMD.
Synchronous Digital Hierarchy. A standard technology for optical fiber-based synchronous data transmission, running on copper cable. The international equivalent of SONET. See also PDH, SONET.
Synchronous Data Link Control. A protocol based on HDLC (High-level Data Link Control). An IBM term for a link protocol used to transfer data between nodes.
Symmetric Digital Subscriber Line. Data transmission over a single telephone line, in which upstream and downstream transmission rates are the same.
Service data unit. Unit of information transferred between a service provider and a service user across the OSI interface.
Segment delay value. A value used in calculating the path delay variance in Ethernet networks.
A second network management module (jumpered to disable retiming) installed in a hub to serve as a secondary link in case a problem occurs with the primary NMM or the link connected to it.
One of the two logical rings of an FDDI network. It can be used as a backup to the primary ring and also to provide additional bandwidth for data. See also primary ring.
One of the five network management application areas defined by ISO; includes tools that allow the network manager to restrict access to various resources in the network. See also network management, ISO.
(1) An electronic path between two network devices.
(2) In structured networking, the physical set of end stations (both users and elements) that form an Ethernet collision domain. The boundaries of a collision domain are defined by bridges or routers.
(3) An Ethernet backplane path in a hub, more precisely known as a backplane segment.
(4) A port or group of ports defined by their connection together. Ethernet segments can be isolated, local, backplane, or cascaded. Token ring segments can be isolated, local, or backplane.
In Ethernet, a single section of bus-type transmission media. In token ring, a single ring of transmission media containing cables, components, and lobes. In FDDI, a single dual ring of transmission media.
Technique used in structured networking to accommodate users from a variety of locations who must be in the same network. A network center splices subsegments from different wiring closets to connect them as a full segment.
(1) The process by which a network protocol breaks long frames into multiple, smaller PDUs.
(2) The act of breaking segments (rings) into multiple smaller segments (rings); for example, to divide a large network into separate smaller networks for the purpose of increasing performance.
(1) In ATM, a sublayer (SAR) of AAL; a process performed on ATM information cells.
(2) In APPN, a flow control operation that functions at SNA layer 4.
A computer or specialized device that provides and manages access to shared network resources, such as hard disks and printers. See also client.
The bit rate that is available to a user for the transfer of user information.
A 9-pin male serial port on a module used to set configuration information such as the module telephone number, location, key, and retiming status from an attached terminal.
Layer 5 of the OSI reference model. Establishes, maintains, and controls a communications session between clients and servers or between peers on a network.
Switch Fabric Module. The Bay Networks Model 5720 ATM Switch Fabric Module is a 16-port ATM-based switch that supports general, switched high-performance network connections.
Shared-media terminology meaning that all devices attached to the LAN share a single communications medium channel, usually a coaxial, twisted pair, or fiber optic cable.
The original LAN configuration in which stations share a single communication channel using a MAC. All stations receive the transmissions of all other stations. Station operation is half-duplex: there can be only one station originating data on the LAN at one time, determined by the MAC protocol. The aggregate bandwidth of all the stations is limited to that provided by the LAN bit rate. See also switched LAN.
Secondary in. In an FDDI network, a port that connects dual attached devices, typically to trunk rings.
Status information frame. A type of station management frame in FDDI that transmits and receives information about the configuration and operational parameters of other stations.
A virtual channel for transporting signaling information.
A low-performance telephone cable that is flat in shape and typically has a silver vinyl jacket, used for telephone patch cables and horizontal distribution cables but not suitable for high-speed data applications.
Switched multimegabit data service (SMDS) Interface Protocol. The protocol used to support SMDS service, consisting of the level 3 protocol data unit containing source and destination addresses and an information field up to 9188 bytes long. See also SMDS.
Switched Internetworking Services (BaySIS).
Serial link connector. Asynchronous expansion module for the Annex 3 and the Remote Annex 4000. See also AnnexTM, Remote AnnexTM.
Serial Line Internet Protocol (IP). A TCP/IP protocol that allows IP packets to be transmitted over a serial link, such as a dial-up or private telephone line.
A location in a network device where a module can be inserted.
Feature in Bay Networks products that allows a host or network management module to be inserted or removed while the chassis remains functional and is receiving power. Also known as hot-swap.
Server message block. A message format derived from the Microsoft/3Com file sharing protocol used to transfer file requests (such as open, close, read, write) between clients and servers. It provides services at the application layer (layer 7) of the OSI reference model and is used in networks such as LAN Manager, LAN Server, and Windows NT.
Switched multimegabit data service. A connectionless, high-speed data service offered by most telephone companies that allows LANs to connect across a wide area network. Other common WAN services include frame relay, PPP, and X.25.
Single-mode fiber (FDDI networks). A laser-driven optical fiber whose core diameter is small enough to limit transmission to a single bound mode, commonly used in long distance communications in excess of three miles. See also MMF.
Single mode fiber-physical medium dependent. A standard for the physical medium dependent (PMD) sublayer that sets the specifications for operating FDDI protocols in a single-mode fiber environment and extends the basic FDDI link distance to 60 kilometers.
System Management Interface Tool.
Station management. An integral specification within the FDDI standard that specifies the network management interface for each protocol layer.
Simple Mail Transfer Protocol. A service designed specifically for electronic mail that functions as a unified post office for addressing mail to all users on all nodes of wide area and local area networks.
Switch NodeTM. A Bay Networks modular, 5-slot Ethernet frame switch providing wire-speed forwarding of network traffic at OSI layer 3. The Switch Node's layer 3 switching capability combines high-speed layer 2 switching with IP routing capabilities. The Bay Networks Accelar product family provides the latest routing switch technology. See also AccelarTM.
Systems Network Architecture. A proprietary network architecture used in IBM systems to connect terminals to a mainframe.
Subnetwork Access Protocol. A version of the IEEE local area network logical link control frame similar to the data link level transmission frame that allows the use of nonstandard higher-level protocols.
A device or software subsystem that functions as a protocol analyzer and statistics probe on a network.
Simple Network Management Protocol. A 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 RFC 1157.
Simple Network Management Protocol, version 2. A combination of proposal updates to SNMP, most of which deal with security.
Secondary out. In an FDDI network, a port that connects dual attached devices, typically to trunk rings.
Start of header. A transmission control character used as the first character of the heading of an information message.
Small office/home office. The small office and home-based segment of the computer and networking market.
Synchronous Optical Network. A family of fiber optic transmission rates ranging from 51.84 Mb/s to 13.22 Gb/s that provides the flexibility to transport many digital signals with different capacities and to provide a design standard for manufacturers. See also SDH.
Synchronous payload envelope. A SONET frame containing overhead information (POH) and actual user data. See also POH.
Bay Networks management application for the Centillion 50/100 and Model 5000BH switches.
A Bay Networks graphical configuration and management application used to configure, monitor, and control network traffic on Bay Networks BayStack 301 Ethernet switches.
Stack Packet Exchange. Bay Networks high-performance system interconnect (bus extension) that allows up to four individual ASN (Access Stack Node) router/bridges integrated in a stack configuration to act as a single router/bridge entity.
A connecting block used in telephone connections, typically consisting of an insulated base covered by four vertical columns of 50 insulation displacement or wire-wrap connectors; also called punchdown block, telco block, Type 66 block, or wiring block.
A configuration in which users in different physical locations or floors share the same ring and applications, with host connectivity through a separate wiring closet concentrator located physically near each workgroup. In the equipment room concentrator, the connection is made by connecting each of the associated ring segments together by way of a Bay Networks System 5000 token ring backplane.
Sequenced Packet Protocol. Xerox Network Systems protocol governing sequenced data.
Service Provisioning System. A Bay Networks licensed software program, supporting BayStream Multiservice and Site Manager software.
Sequenced packet exchange. Novell NetWare protocol set implemented over IPX to form a transport layer interface.
Signal quality error test. A collision test signal sent after transmissions by IEEE 802.3 medium attachment units.
Structured Query Language. ANSI and ISO standard query language system developed by IBM for use in mainframe applications with relational database systems.
A communication function that turns receiver amplifier circuits off when noise is the only signal present. In an Ethernet transceiver, this function prevents noise from propagating to all network segments.
Source route or source routing. A token ring standard that supports routing frames through a multiple ring. Each source route frame carries information about the route the frame must follow to reach its destination.
Static random access memory or static RAM. A computer memory that retains its contents as long as power is applied and does not need refreshing.
Source route bridge or source route bridging. A systems-level concept used in many token ring environments where the end stations take on the responsibility of learning the exact ring-to-ring path a packet must take to reach its destination and provide all that information in a special routing field of the LAN packet.
Status report frame. A type of station management frame in FDDI that periodically announces conditions of interest to the FDDI manager, such as configuration changes, undesirable conditions, and MAC neighbor changes.
Specifically routed frame. Frame generated by an end station that receives an ARE or STE frame. The SRF contains a list of routing designators and maps a specific path back to the source end station.
System Resource Module-Front. This optional unit for BLNs and BCNs provides 1 Gb/s total bandwidth and PPX redundancy.
System Resource Module-Link. Each BLN and BCN includes one SRM-L, which provides a 25-pin D-connector for a terminal or modem to access the Technician Interface (software) for diagnostic and maintenance operations.
Source route transparent. A token ring standard that supports both source route and transparent bridging frames between bridges and end stations on multiple-ring token ring networks.
Source route transparent bridge. Device that can support both source route and non-source route end stations.
Switching System. Associated with SMDS.
Signaling System 7. A standard signaling protocol used in PSTN, supporting advanced calling services. This protocol is supported by Bay Networks Versalar products. See also PSTN, VersalarTM.
Source Service Access Point. An address field used be logical link control (LLC) protocols to identify the specific service access point that initiated a protocol data unit (PDU).
System services control point.
Single Sync/Single Ethernet (link module).
Silicon Switch Fabric. A part of Accelar routing switches that contains the core switch fabric and the CPU subsystem for chassis operation. The SSF is built into the chassis of Bay Networks Accelar1100/1150 models. An SSF module is available for Bay Networks Accelar 1200/1250 models, including a second optional module for additional redundancy.
SMDS to access Server Interface.
Straight-tip connector. An AT&T bayonet connector for fiber optic cable that uses a precision ceramic plug and a flexible sleeve. See also SC connector.
Subscriber/Transport interface.The boundary between the user and an ISDN network.
Spanning tree algorithm. An algorithm used to ensure that a single data path between any two stations on an extended LAN is implemented at any specific time. A technique for determining the best path between segments of a multiloop, bridged network.
Hubs that look and act like standalone hubs; however, several can be connected together, usually by a short length of cable, to act like a modular hub that can be managed as a single unit. One manageable hub used with a stack can provide the management for all other hubs in the stack.
Bay Networks probe management product incorporating RMON and RMON2 capabilities in a universal, stackable device. See also RMON, RMON2.
Single products with a number of ports. Usually include some method of linking them to other standalone hubs by connecting with a length of 10BASE5 coaxial twisted pair cable between individual ports on each hub. Usually the least expensive hubs and often not managed. Best suited for small, independent workgroups with fewer than 12 users.
A Level 1 SNMP agent for a Bay Networks device. It monitors the device and gathers statistical data in MIB format to report to the network management station. See also agent, Advanced agent, Advanced AnalyzerTM agent.
A coaxial cable specified by the IEEE 802.3 10BASE5 standard, approximately 12 mm in diameter and usually colored yellow, to which devices are attached by means of DB-15 connectors and a cable-mounted transceiver; also called thick coaxial cable or thick Ethernet.
An obsolete 1 Mb/s 802.3 standard, star-configured Ethernet local area network from AT&T Information Systems, based on 802.3 type 10BASE5 over twisted pair cables.
LAN topology in which each peripheral node is connected to a hub by an individual length of twisted pair cable, in a layout resembling a star. Each node is connected to a hub, which acts as a focal point for network cabling. All information passes through the central point and is passed to the nodes. See also bus topology, ring topology.
A device, such as a personal computer, workstation, server, bridge, or router, connected to a network at a single location; also called data terminal equipment, DTE, host, host device, or node.
Spanning tree explorer. A single frame generated by an end station configured for spanning tree broadcast routing that follows a loop-free path from source to destination.
SNMP Transport Gateway. Bay Networks software application that provides the integration of SNMP-manageable devices into existing IBM SNA networks.
Synchronous Transfer Mode. Clocked data transmission, where the receiving device knows when to expect the next unit of data.
Synchronous Transport Module. A definition of the electrical level signal rate and frame structure for SDH networks. STM-1 is equivalent to STS-3 for SONET. See also SDH.
A device that receives packets completely on one interface and queues them for transmission out of the destination interface; for example, a device that supports interfaces running at different speeds, such as 10 Mb/s and 100 Mb/s Ethernet. A data-transmission scheme using a message-switching technique that temporarily stores a message at intermediate points before retransmitting it to its next destination.
Shielded twisted pair (cable). A cable consisting of two insulated wires, twisted together and surrounded by a braided metal shield or foil under the outer insulation. Shielding provides more protection against EMI (electromagnetic interference). See also IBM Cabling System, UTP.
Spanning Tree Protocol. Technique based on the IEEE 802.1 standard that detects and eliminates logical loops in a bridged or switched network. When multiple paths exist, the STP algorithm configures the network to use only the most efficient path.
A cabling method used to design network cabling structures to universal standards and conformity. With structured wiring, all network stations are physically star-wired to intelligent hubs (hubs that can be monitored easily and turned off if necessary). Structured cabling makes adding users, moving users, or making other physical changes very simple. Supports Ethernet star topology.
A method of designing the network fabric in which workgroup hubs are connected via fiber optic trunks to a hub located at a centralized location, referred to as a network center. Structured networking decouples physical connections from logical associations, allowing networks to be built around the way organizations are structured instead of around the way buildings are structured.
Synchronous transport signal - level 3 concatenated. Signal obtained by byte interleaving three STS-1 (51.840 Mb/s) signals together. The rate of STS-3c is three times 51.840 Mb/s or 155.52 Mb/s.
Synchronous transport signal level N. A SONET term for a signal obtained by interleaving N STS-1 signals together.
A 125-microsecond frame structure composed of STS path overhead and bandwidth for payload. The term generically refers to STS-1 SPEs and
STS-Nc SPEs.
Serial (SDLC) tunneling. Process that allows SDLC traffic to be bridged over token ring LANs. See also SDLC.
Stored upstream address. In token ring networks, the stored address of the upstream neighbor.
(1) A division of a layer in the International Organization for Standardization (ISO) Open Systems Interconnection (OSI) reference model; for example, the logical link control (LLC) sublayer in the data link layer (DLL).
(2) A division of a protocol layer.
A physically or logically independent portion of a network, distinguished by a subnet number. A subnet is to a network what a network is to an internetwork. See also network.
The subnet portion of an IP address. In a subnetted network, the host portion of an IP address is split into a subnet portion and a host portion using an address (subnet) mask. See also Class A/B/C address, IP address, network address.
A template or filter imposed on an Internet address for the purpose of separating the members of a particular subnetwork. The "1" bits in the subnet mask indicate the significant bit positions in the subnet address; the "0" bits indicate bit positions that are ignored.
A Bay Networks module for System 3000 hubs that manages the current between two redundant power supplies.
Bay Networks proprietary distributed software that collects and analyzes raw data from embedded device agents within its domain before sending the synthesized data to the management system.
Switched virtual circuit. On-demand connection between an ATM or frame relay source and destination that lasts for the duration of the transmission.
Segment variability values. The maximum increase to the bit size of the preambles of Ethernet packets as they travel through each repeater on the path.
A network device that completes or selects a path for data circuits, packets, frames, or cells to follow from a local device input to a specific local output at wire speed or slightly lower. Switches enable simultaneous transmissions to take place, providing up to 155 Mb/s of network bandwidth.
A Bay Networks ATM embedded controller, such as the Model 5740 Switch Control Module, that handles all aspects of chassis operation (switch management, connection management, SNMP control).
A matrix of binary switching elements across an ATM backplane.
A Bay Networks modular, 5-slot Ethernet frame switch providing wire-speed forwarding of network traffic at OSI layer 3. The Switch Node's layer 3 switching capability combines high-speed layer 2 switching with IP routing capabilities. The Bay Networks Accelar product family provides the latest routing switch technology. See also AccelarTM.
A generalized term encompassing all switched approaches to providing LAN information transport, including frame switching, hybrid switching, and cell switching. Also a LAN configuration in which stations connect to a switch, operate in full-duplex mode, and do not use media access control. All stations have access to nearly the total aggregate bandwidth available.
Establishment of a direct transmission path from a particular station to another station. Switching provides high-throughput (wire-speed) connections on data networks.
Bay Networks software application that manages the Model 3328 Ethernet Switching Engine, monitors switches, monitors LANs, and can be used to simulate alternative LAN designs.
An Accelar 1200 feature using two Silicon Switch Fabric modules that provide backup and resumption of switching functionality in case of failure.
Signals that are sourced from the same timing reference. Causes the interval between successive bits, characters, or events to remain constant or "locked in" to a specific clock frequency.
System Controller. Accounting program in Novell NetWare LANs that enables a file server to charge for network services.
Bay Networks family of Ethernet hubs for small, standalone workgroups.
Bay Networks family of hub products designed for small to midsize networks. Includes Ethernet, token ring, and FDDI hubs.
Bay Networks family of hub modules designed for integrated Ethernet, token ring, and FDDI connectivity; internetworking; and network management capabilities.
Bay Networks family of multi-LAN switching hubs with host, management, network, and internetworking modules. Allows integration of Ethernet, token ring, FDDI, and ATM network access methods into a single chassis.