[Home][Adtran][Cisco][FatPipe][Fluke][Multi-Tech][RAD][Sycamore]

Home_button.gif (1313 bytes) Special_button.gif (1327 bytes) SEARCH.GIF (1278 bytes) QUOTE.GIF (1281 bytes)

Glossary Section "R" ( Definitions )

Guide -  Select first letter of word:
0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

RADIUS Remote Authentication Dial In User Service. A security and authentication mechanism for remote access.

RADSL Rate Adaptive Digital Subscriber Line

RAID Redundant Array of Independent Drives

RARP Reverse Address Resolution Protocol. The Internet protocol a diskless host uses to find its Internet address at startup. RARP maps a physical (hardware) address to an Internet address.

RBOC Regional Bell Operating Company.

RBS Robbed Bit Signaling is used in T1 circuits. Instead of having a specific timeslot dedicated to provide signal (as is true with ISDN) , signaling bits for on-hook and off-hook are within the sixth, twelfth, eighteenth and twenty-fourth frames of each time slot. RBS is sometimes called CAS (Channel Associated Signaling)  because it takes bits from the bearer channels for signaling.

RDI Remote Defect Indication

reassembly The process by which an IP datagram is "put back together" at the receiving host after having been fragmented in transit.

repeater A device which propagates electrical signals from one cable to another without making routing decisions or providing packet filtering. In OSI terminology, a repeater is a Physical Layer intermediate system.

replication The process of keeping a copy of data, either through shadowing or caching.

RFC Request For Comments. The document series, begun in 1969, which describes the Internet suite of protocols and related experiments. Not all (in fact very few) RFCs describe Internet standards, but all Internet standards are written up as RFCs.

RFS Remote file System. A distributed file system, similar to NFS, developed by AT&T and distributed with their UNIX System V operating system.

RIP Routing Information Protocol. A protocol used to exchange routing information among a set of computers connected by a LAN. RIP uses hop counts as a routing metric.

RJ11 A 4 position modular jack most commonly used for phone connections. The standard single line phone uses only 2 of the 4 wires.

RJ14 is used with two line phones and leased line modems (physically an RJ11, but it uses 4 wires instead of 2)

RJ45 An 8 position modular jack  (picture)

RJ48C Registration Jack   This is an 8 position modular jack commonly used for connecting to 1.544 Mpbs Digital Service.

RJ48S This is for DSU service at 64,000 bps or lower. Physically it is an RJ45.

rlogin A service offered by Berkeley UNIX which allows users of one machine to log into other UNIX systems (for which they are authorized) and interact as if their terminals were connected directly. Similar to Telnet.

RMON Remote Network Monitoring. Part of the SNMP network management framework.

robbed bit signaling ( RBS ) Robbed Bit Signaling is used in T1 circuits. Instead of having a specific timeslot dedicated to provide signal (as is true with ISDN) , signaling bits for on-hook and off-hook are within the sixth, twelfth, eighteenth and twenty-fourth frames of each time slot. RBS is sometimes called CAS (Channel Associated Signaling)  because it takes bits from the bearer channels for signaling.

ROADM Re-configurable Optical Add-Drop Multiplexer

RoHS Restriction of the use of certain Hazardous Substances in electrical and electronic equipment in the EU (European Union) market. This Directive bans the placing on the EU market new electrical and electronic equipment containing more than agreed levels of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) flame retardants. 

ROI Return on investment

RS-422 is standard using full duplex differential signal on two pairs of wires. Maximum range 4000 ft. Maximum speed 10 Mbps.

RS485 is a standard for half duplex data communications which is frequently used in multi-drop applications. Most commonly this is a 2-wire application. As many as 32 driver/receiver pairs can share a multidrop RS485 network. While many of the characteristics of RS485 are similar to RS422 the voltage range is greater.

RTMP Routing Table Maintenance Protocol

RTT Round-Trip Time A measure of the current delay on a network.

RTU Remote Terminal Unit

routed Route Daemon. A program that runs under 4.2 or 4.3BSD UNIX systems (and derived operating systems) to propagate routes among machines on a local area network. Pronounced "route-dee."

router A system responsible for making decisions about which of several paths network (or Internet) traffic will follow. To do this, it uses a routing protocol to gain information about the network and algorithms to choose the best route based on several criteria known as "routing metrics." In OSI terminology, a router is a Network Layer intermediate system. Historically, routers were called "gateways" in Internet terminology. See bridge, gateway, repeater.

routing The process of selecting the correct interface and next hop for a packet being forwarded.

routing metric The method by which a routing algorithm determines one route is better than another This information is stored in routing tables. Such tables include reliability, delay bandwidth, load, MTUs, communication costs, and hop count..

RPC Remote Procedure Call. A popular paradigm for implementing the client-server model of distributed computing. A request is sent to a remote system to execute a designated procedure, using arguments supplied, and the result returned to the caller. There are many variations and subtleties, resulting in a variety of different RPC protocols.

RS-232- An EIA-specified physical interface with associated electrical signaling between DCE and DTE. The most commonly employed interface between computer devices and modems. While this term is still used, it is more correctly an EIA-232-D.

RS-449 The physical connection for RS449 is generally a DB37.

RS-530 The physical connector use for RS530 is generally a DB25. This superseded the RS-449. The RS-530 is a balanced interface that was designed to replace the more expensive V.35 connector. RS-530 can operate to speeds of 2 Mpbs.

RSA A public-key cryptographic system which may be used for encryption and authentication. It was invented in 1977 and named for its inventors: Ron Rivest, Adi Shamir, and Leonard Adleman.

RSVP Resource Reservation Protocol. RSVP is a control protocol for use in multimedia applications to indicate to transmitting nodes the nature (such as bandwidth, jitter, or maximum burstiness) of the packet streams that they want to receive.

RTFM Read The Fantastic Manual. This acronym is often used when someone asks a simple or common question. The word "Fantastic" is usually replaced with a four letter variation and hand signals.

RTP Real Time Transport Protocol. The standard protocol for streaming applications developed within the IETF.

RTS - Request to Send is a signal sent by one modem to another advising that the modem is available and requesting that data be sent.

RTSC Read The Source Code.

[return to guide] [home page] [specials] [suggest new words for glossary]

 

                    Immediate price quote - Call 727-398-5252

Specials   E-mail us     Bookmark this site     Important Notices     Line Card

Use Visa to purchase Data Communications Equipment    Use MasterCard to purchase Data Communications Equipment
E-mail: Webmaster about this data communications equipment site.
Last modified: May 13, 2014
1998-2017 Cutter Networks Inc - All rights reserved