Reference interface; also reference point. A physical or conceptual point where two ISDN functions merge. ISDN networks include four main reference interfaces/points:
Remote Access Concentrator. Bay Networks Versalar products, the Model 8000 system and Model 5399 module are dial-in remote access servers. Both support up to 48 T1 modems or 62 E1 modems and have x2 or K56flex capability, featuring industry-leading dial access density, call management, and BayDSP modem technology. See also BayDSPTM, VersalarTM.
Remote Access Dial-In User Services. A combination of IETF RFCs 2138 and 2139 that provides authentication, authorization, and accounting for remote dial access users.
Rate Adaptive ADSL. A version of ADSL where modems test the (telephone) line and adapt their operating speed to the fastest line speed possible.
Resource allocation frame. A type of SMT frame in FDDI that defines the allocation of network resources.
Remote alarm indication, or indicator. A signal of an error condition, sent from one end of a SONET path to another, thus providing end-to-end failure indication.
Random access memory. The main working memory of a computer in which program instructions and data are stored where they are directly accessible to the central processing unit (CPU). Often called read/write memory to distinguish from read-only memory.
A testing and debugging process that involves sending an Internet Control Message Protocol (ICMP) echo request to a range of IP addresses to determine which devices respond. A response indicates that the device address is active, but it does not specify the device type.
Reverse Address Resolution Protocol. Internet protocol used by a diskless machine at startup to find its Internet address. The machine broadcasts a request containing its physical hardware address, and a server responds by sending the machine its Internet address.
Remote access server. A server residing at an ISP network to provide tunneling capability from a remote user to the corporate network. See also L2TP, LAC, LNS, TMS, VPN.
Regional Bell Operating Companies. United States telecommunications companies providing large, traditional networks and services.
Receive data. An RS-232-C standard hardware signal to carry data from one device to another. Also abbreviated Rx or Rxd.
Relational database management system.
Resource denied frame. A type of SMT frame in FDDI used by a station to respond to an unsupported optional frame class or unsupported version of SMT.
Reliable Datagram Protocol. A protocol that provides reliable datagram service on top of the standard unreliable datagram service provided by the Internet Protocol.
Pertaining to actual time during which a process transpires. An application in which response to input is fast enough to affect subsequent input, as when conducting the dialog that takes place at terminals in interactive systems.
The minimum received peak optical power that will produce a recovered electrical signal with minimal timing distortion.
A provision of duplicate, backup equipment and/or software processes in case of primary equipment or system failure.
Ring error monitor. A ring-resident function that maintains statistical records on token ring operating errors.
Any network device that is accessible only by means of communication over a digital or analog (dial) network.
Bay Networks product family of terminal and communication servers that provides local and remote multiuser system access.
An Annex communication server application that permits users to manage multiple systems or network devices from a single remote console. See also AnnexTM.
A type of remote access to a network wherein a remote PC dials into and takes control of a PC on the network; only screen and keyboard updates are passed over the connection.
An indication of far-end receive failure, as seen by a port that is not receiving a light signal.
A type of remote access to a network where a remote PC or workstation dials into and participates as a fully functioning end node on the network while also taking advantage of the processing power of the remote device (such as a server).
An office that is geographically distant from the corporate network.
A verification of proper connectivity between transmit and receive fibers. Bay Networks 10BASE-FL products include a proprietary version because 10BASE-FL standards do not address remote signaling.
A device inserted at intervals along a network to boost and amplify analog signals or regenerate digital signals being transmitted, used to connect segments of a network medium together into a single collision domain. A repeater helps signals travel farther over a cable because the quality and the strength of a signal decay over distance. A repeater operates at the Open Systems Interconnection (OSI) physical layer.
A packet used to reset a virtual circuit at the interface between the data terminal equipment and the data circuit-terminating equipment.
Hardware or software that can be shared over a LAN; for example, printers, modems, disk drives, and directories.
A module that implements IEEE 802.3 repeater functions for data entering a concentrator and also provides termination for the concentrator backplane.
Radio Frequency. Electromagnetic wave frequency used for radio transmissions.
Request for Comments. A document (for example, RFC 1483, RFC 1577) describing proposals and standards for internetworking protocols, such as the Internet Protocol (IP).
Radio frequency interference. Electromagnetic radiation produced by some electronic or electromechanical devices that can interfere with other radio frequency signals.
Ring in. The input port of a ring in/ring out concentrator module in a token ring network.
Routing information field. A bit field that contains routing information.
Routing information indicator. The first bit of the source address of a token ring source routed frame; part of the RIF.
A set of stations wherein information is passed sequentially between stations, each station in turn examining or copying the information, returning it finally to the originating station.
A cable network topology characterized by a cable that forms a completely closed loop. Contrast with star and bus topologies. A network in which every node has exactly two branches connected to it.
A network topology where stations are connected to the network at a repeater device. The repeaters are linked to each other to form a single, closed, unidirectional loop. See also topology.
Bay Networks System 2000 and System 3000 token ring hub agent feature that provides ring/station-level isolation and nonisolation soft error diagnosis, and gathers and reports station adapter card profiles.
Routing Information Protocol. A distance vector protocol in the IP suite (used by IP and IPX network-layer protocols) that enables routers in the same autonomous system to exchange routing information by means of periodic updates. For RIP, the "best" path to a destination is the path with the fewest hops. RIP computes distance as a metric, usually the number of hops from the origin network to the target network.
Remote Imaging Protocol. A graphics format designed for transmitting graphics over low-speed lines.
Ring in/ring out. Connections used to connect token ring hubs together.
Reduced Instruction Set Computer. A relatively inexpensive processor that recognizes a limited number of assembly language instructions.
A four-contact or six-contact modular connector commonly used in telephones, fax devices, modems, and other analog (dial) network devices.
Common term for the type of connector used in terminating 10BASE-T UTP or STP cabling at the NIC or hub. An 8-pin modular connector used for data communications (IEC 603-7).
Redundant Line Cord. A BCN configuration supporting two 220 VAC power feeds for system redundancy. See also BCN®.
Remote monitoring. An SNMP protocol used to manage networks remotely. It collects statistics from the data link layer of the OSI reference model (layer 2) and enables a management station to monitor network devices from a central location. It provides multivendor interoperability between monitoring devices and management stations (RFC 1757).
Advanced RMON standard that adds broader vendor compliance and enterprise-wide traffic monitoring at the network through application layers of the OSI reference model, and additional information about network traffic at these layers. See also MIB, SNMP.
The interface defined by the DCE/MCE assigned to a network segment for RMON data collection.
Ring out. The output port of a ring in/ring out concentrator module in a token ring network.
Moving an end user device from one location to another within a network while still maintaining unique identification and other properties. Mobile devices (for example, phones, computers) in a cellular packet-switched network can roam areas without losing communication.
Read-only memory. An integrated circuit for memory storage that permanently stores information, even after power has been switched off.
The highest-level concentrator in an inverted, tree-structured network.
The path that network traffic takes from its source to its destination. Also, a possible path from a given host to another host or destination.
(1) A device that forwards traffic between networks, based on network layer information and routing tables. It decides which path network traffic will follow, using routing protocols to gain information about the network and algorithms to choose the best route based on a "routing matrix." In OSI terminology, a router is a network layer intermediate system. See also bridge.
(2) A protocol-specific internetworking component configured to know which LAN segments it can communicate with and that takes responsibility for getting packets from one segment to another via the best way. A router must be able to recognize all of the different network layer protocols that may be used on the networks they link together. A multiprotocol router can route many different protocols.
Bay Networks graphical information display. RouterMan gathers and displays fault and performance statistics for the overall router, individual protocols, and router interfaces. A real-time monitoring, management, and diagnostic application for network routers.
The act of connecting single end users to a dedicated router port (dedicated routed LAN).
A module that connects physically separated networks, including networks that operate under different protocols or run on different media or are supplied by different vendors.
The process of efficiently moving data packets among subnetworks by selecting the correct interface and next hop for a packet being forwarded. See also hop, router.
A set of routers exchanging routing information within an administrative domain. See also AD, router.
Protocol used by routers to report their status to other routers in the network and to keep their internal tables up to date.
A class of switch that integrates IP routing into hardware, allowing IP traffic to move 10x faster than a router (that is, at Gigabit Ethernet speeds). See also AccelarTM.
A table with entries for every route known to the local device. Entries contain data such as the destination address, next-hop address, and various route metrics.
Recognized private operating agencies.
Redundant power supply unit. In a Bay Networks chassis, a secondary power supply that provides an immediate backup in case the main power supply fails to prevent any impact on the network.
The Electronic Industries Association (EIA) standard for the 25-pin (or 9-pin subset) serial interface used to connect personal computers or terminals to communications equipment, such as modems and fax devices.
The Electronic Industries Association (EIA) 37-pin standard for higher-speed (up to 2 Mb/s) serial binary data interchange using synchronous data-link lines.
Resource Reservation Protocol. Protocol that provides a method for real-time applications to communicate requirements to network elements along the data path. RSVP conveys Quality of Service (QoS) information between network elements and the application. In addition to the data used to directly invoke QoS control services, RSVP carries authentication and policy information needed to manage the use of these services.
Routing Table Management Protocol. The protocol that lets an AppleTalk bridge or gateway dynamically discover routes to the various AppleTalk networks within an internetwork.
Rapid Transport Protocol. A connection-oriented, full-duplex protocol that supports data in high-speed networks at APPN network node end points. RTP supports nondisruptive path switching, end-to-end error recovery, and end-to-end flow and congestion control.
Request to send. RS-232-C standard hardware signal requesting permission to transmit.
An Ethernet packet with a frame size between 8 and 63 bytes with frame check sequence (FCS) or alignment errors. The runt packet is presumed to be a fragment resulting from a collision.
Receive data. RS-232-C standard hardware signal to carry data from one device to another. Also called RD.
Return to zero. The signal pauses at zero voltage between each pulse when making zero crossings.