RADIUS: Remote Authentication Dial In User Service
Remote Authentication Dial In User Service (RADIUS) is a protocol for carrying authentication, authorization and configuration information between a Network Access Server which desires to authenticate its links and a shared Authentication Server. RADIUS uses UDP as the transport protocol. RADIUS also carries accounting information between a Network Access Server and a shared Accounting Server.
Standard Organization: IETF
Reference Document: RFC 2865 and 2866

RADSL: Rate Adaptive DSL
Rate-adaptive Asymmetric Digital Subscriber Line (RADSL) is a variation of ADSL which automatically adjusts the connection speed depanding on the quality and length of the telephone line. In RADSL, the broadband modem is configured at startup to test the phone line and adjust the data rate. RADSL typically operates at a lower date rate than regular ADSL. Like ADSL, RADSL provides relatively more bandwidth for downloads and less for uploads.
Standard Organization: ITU-T

RANAP: Radio Access Network Application Part
Radio Access Network Application Part (RANAP) is the Radio Network Layer signaling protocol used in a UMTS system on the Iu interface. It is responsible for functions including the setting up of a RAB (Radio Access Bearer) between the CN (Core Network) and the RNC (Radio Network Controller).
Standard Organization: ITU-T

RARP: Reverse Address Resolution Protocol
Reverse Address Resolution Protocol (RARP) allows a physical machine in a local area network to request its IP address from a gateway server's Address Resolution Protocol (ARP) table or cache. A network administrator creates a table in a local area network's gateway router that maps the physical machines (or Media Access Control [MAC]) addresses to corresponding Internet Protocol addresses.
Standard Organization: IETF
Reference Document: RFC 903

RAS: Registration, Admission and Status
Registration, Admission and Status (RAS), defined in the ITU-T H.225.0/RAS, is the protocol between endpoints (terminals and gateways) and gatekeepers. The RAS is used to perform registration, admission control, bandwidth changes, status, and disengage procedures between endpoints and gatekeepers. An RAS channel is used to exchange RAS messages. This signaling channel is opened between an endpoint and a gatekeeper prior to the establishment of any other channels.
Standard Organization: ITU-T
Reference Document: H.225

RCP: Remote Copy Protocol
Remote Copy Protocol (RCP), a command on the Unix operating systems, is a protocol that allows users to copy files to and from a file system residing on a remote host or server on the network. RCP uses TCP to ensure the reliable delivery of data. But RCP can use kerberos for authentication. This command has been largely superseded by more secure methods, such as the scp and sftp commands based on SSH.
Standard Organization: Unix

RDP: Reliable Data Protocol
Reliable Data Protocol (RDP) is a connection-oriented transport protocol designed to efficiently support the bulk transfer of data for such host monitoring and control applications as loading/dumping and remote debugging. It attempts to provide only those services necessary, in order to be efficient in operation and small in size.
Standard Organization: IETF
Reference Document: RFC 1115

RDP: Remote Desktop Protocol
Remote Desktop Protocol (RDP) is a Microsoft protocol designed to provide remote display and input capabilities over network connections for Windows-based applications running on a server. RDP was first released with Windows Terminal Services (TS) 4.0 based on an existing ITU T.120 family of protocols with limited features and performances. Windows 2000 TS and the RDP 5.0 protocol include several critical new features together with some significant performance improvements over all types of network connections, including LAN, WAN, and dial-up.
Standard Organization: Microsoft

RFC: Request for Comments
Request for Comments (RFC), a series of documents about the Internet technologies, started in 1969 (when the Internet was the ARPANET). The documents discuss many aspects of computing and computer communication focusing in networking protocols, procedures, programs, and concepts, but also including meeting notes, opinion, and sometimes humor. The specification documents of the Internet protocol suite, as defined by the Internet Engineering Task Force (IETF) and its steering group (the IESG), are published as RFCs. Many of the TCP/IP protocols and PPP protocols are defined by rfc's.
Standard Organization: IETF

RGMP: Router Port Group Management Protocol
The Router Port Group Management Protocol (RGMP) is defined by Cisco Systems to address the limitations of Internet Group Management Protocol (IGMP) in its Snooping mechanism. RGMP is used between multicast routers and switches to restrict multicast packet forwarding in switches to those routers where the packets may be needed. RGMP is designed for backbone switched networks where multiple, high speed routers are interconnected.
Standard Organization: Cisco

RIP: Routing Information Protocol
Routing Information Protocol (RIP) is a standard for exchange of routing information among gateways and hosts. This protocol is most useful as an "interior gateway protocol". In a nationwide network such as the current Internet, there are many routing protocols used for the whole network. The network will be organized as a collection of "autonomous systems". Each autonomous system will have its own routing technology, which may well be different for different autonomous systems. The routing protocol used within an autonomous system is referred to as an interior gateway protocol, or "IGP".
Standard Organization: IETF
Reference Document: RFC 1058

RIP2: Routing Information Protocol version 2
Routing Information Protocol version 2 (RIP2) is an extension of the Routing Information Protocol (RIP), intended to expand the amount of useful information carried in the RIP2 messages and to add a measure of security. RIP2 is a UDP-based protocol. Each host that uses RIP2 has a routing process that sends and receives datagrams on UDP port number 520. RIP and RIP2 are for the IPv4 network while the RIPng is designed for the IPv6 network.
Standard Organization: IETF
Reference Document: RFC 2453

RIPng: Routing Information Protocol for the IPv6
RIPng, a routing information protocol for the IPv6, is based on protocols and algorithms used extensively in the IPv4 Internet. In an international network such as the Internet, there are many routing protocols used for the entire network. The network will be organized as a collection of Autonomous Systems (AS). Each AS will have its own routing technology, which may differ among AS's. The routing protocol used within an AS is referred to as an Interior Gateway Protocol (IGP). A separate protocol, called an Exterior Gateway Protocol (EGP), is used to transfer routing information among the AS's.
Standard Organization: IETF
Reference Document: RFC 2080

RIPX: Routing Information Protocol for IPX
Routing Information Protocol for IPX (RIPX), a Novell NetWare protocol, is used to collect, maintain and exchange correct routing information among gateways within the Internet for NetWare nodes.
Standard Organization: Novell

rlogin: remote login
Remote login (rlogin) is a UNIX remote login command that allows an authorized user to log in to other UNIX machines (hosts) on a network and to interact as if the user were physically at the host computer. Once logged in to the host, the user can do anything that the host has given permission for, such as read, edit or delete files.
Standard Organization: IETF
Reference Document: RFC 1282

RLP: Radio Link Protocol
Radio Link Protocol (RLP) is a link layer protocol used for 2G(GSM and cdmaOne) and CDMA-2000 (3G) network-based error correction to ensure robust data transmission. RLP terminates at the Mobile Station(MS) and the Interworking Function(IMF) generally located at the Mobile Switching Centre(MSC). Cellular networks such as GSM and CDMA and CDMA-2000 use different variations of RLP.
Standard Organization: IEEE 802.20

RM Cell: Resource Management Cell
Resource Management (RM) cell is protocols in the ATM suite for Available Bit Rate (ABR) services. RM Cells are used to convey ATM network status (available bandwidth, congestion levels) and request peak cell rates for ATM blocks. RM cells are standard 53-byte ATM cells with the payload type field in the header set to a binary value of 110. Forward RM cells are sent to the destination end-system on the same VC as data cells and at an interval defined by the number of RM cells (NRM) parameter. By default, a source ABR device sends one forward RM cell for every 32 data cells.
Standard Organization: ITU-T

RMON: Remote Monitoring
Remote Monitoring (RMON) is a standard monitoring specification that enables various network monitors and console systems to exchange network-monitoring data. RMON provides network administrators with more freedom in selecting network-monitoring probes and consoles with features that meet their particular networking needs. RMON has two versions: RMON1 and RMON2.
Standard Organization: IETF
Reference Document: RFC 2819 and RFC 2021

RMON1: Remote Network Monitoring version 1
Remote Network Monitoring version 1 (RMON1 or RMONv1) can now be found on most modern network hardware, defined 9 MIB groups for basic network monitoring.
Standard Organization: IETF
Reference Document: RFC 2819

RMON2: Remote Network Monitoring version 2
Remote Network Monitoring version 2 (RMON2 or RMONv2) is an extension of RMON that focuses on higher layers of traffic above the medium access control (MAC) layer. RMON2 has an emphasis on IP traffic and application level traffic. RMON2 allows network management applications to monitor packets on all network layers.
Standard Organization: IETF
Reference Document: RFC 2021

ROSE: Remote Operations Service Element Protocol
The Remote Operations Service Element Protocol (ROSE), an ISO protocol, is a protocol that provides remote operation capabilities, allows interaction between entities in a distributed application and, upon receiving a remote operations service request, allows the receiving entity to attempt the operation and report the results of the attempt to the requesting entity. The ROSE protocol itself is only a vehicle for conveying the arguments and results of the operation as defined by the application.
Standard Organization: ISO

RP: DECnet Routing Protocol
DECnet Routing Protocol (RP), similar to Routing Information Protocol in the IP network, distributes routing information among DECnet hosts.
Standard Organization: DEC/HP

RPC Mount Procedures
RPC Mount Procedures are the services for the Remote Procedure Call (RPC) to initiate client access to a server supporting RPC.
Standard Organization: Sun

RPC NFS Procedures
RPC NFS Procedures refer to the Network File System (NFS) implementation using the RPC Protocol. All NFS operations are implemented as RPC procedures.
Standard Organization: Sun

RPC: Remote Procedure Call
Remote Procedure Call (RPC) is a protocol for requesting a service from a program located in a remote computer through a network, without having to understand the underlayer network technologies. RPC presumes the existence of a low-level transport protocol, such as TCP or UDP, for carrying the message data between communicating programs.
Standard Organization: Sun / IETF
Reference Document: RFC 1831

RPC-PMP: RPC Port Mapper Procedures
RPC Port Mapper Procedures are the Port Mapper (PMAP) protocol which manages the allocation of transport layer ports to network server applications, which eliminates the need to reserve permanently a port number for each application because only the PMAP application itself requires a reserved port.
Standard Organization: Sun

RPR: Resilient Packet Ring
Resilient Packet Ring (RPR), defined by the IEEE's 802.17 working group, is a Layer 2 MAC-based technology to bring SONET-like abilitites to metro Ethernet networks, by adding support for a ring topology and fast recovery from fiber cuts and link failures at Layer 2. RPR uses Ethernet switching and a dual counter-rotating ring topology to provide SONET-like network resiliency and optimized bandwidth usage, while delivering multipoint Ethernet/IP services. RPR maintains its own protection scheme and uses physical-layer alarm information and Layer 2 protocol communications to detect node and/or link failures. When a failure is detected, the RPR switching mechanism restores networks in less than 50 milli-seconds.
Standard Organization: IEEE
Reference Document: IEEE 802.17

rsh: Remote Shell Protocol
Remote Shell Protocol (rsh) is a protocol that allows a user to execute commands on a remote system without having to log in to the system. For example, rsh can be used to remotely examine the status of a number of access servers without connecting to each communication server, executing the command, and then disconnecting from the communication server. rsh originated as part of the BSD Unix operating system as part of the rlogin package on 4.2BSD in 1983. rsh has since been ported to other operating systems. rsh is mostly replaced by a more secured protocol called Secure Shell protocol(SSH) in today's environment.

RSS: Really Simple Syndication
Really Simple Syndication (RSS) is a lightweight XML format designed for sharing headlines and other Web content. RSS becomes a popular means of sharing content between sites. RSS solves myriad problems webmasters commonly face, such as increasing traffic, and gathering and distributing news. RSS can also be used for additional content distribution services.
Standard Organization: W3C

RSTP: Rapid Spanning Tree Protocol
Rapid Spanning Tree Protocol (RSTP), defined in the IEEE 802.1w, is an evolution of the Spanning Tree Protocol (STP) defined in IEEE 802.1d. RSTP provides for faster spanning tree convergence after a topology change. RSTP provides a loop free topology for any LAN or bridged network.
Standard Organization: IEEE
Reference Document: IEEE 802.

RSVP: Resource Reservation Protocol
Resource Reservation Protocol (RSVP) is a resource reservation setup protocol designed for quality integrated services over the Internet. RSVP is used by a host to request specific qualities of service from the network for particular application data streams or flows. RSVP is also used by routers to deliver quality-of-service (QoS) requests to all nodes along the path(s) of the flows and to establish and maintain state to provide the requested service. RSVP requests will generally result in resources being reserved in each node along the data path.
Standard Organization: IETF
Reference Document: RFC 2205

RSVP-TE: Resource Reservation Protocol C Traffic Extension
The Resource Reservation Protocol C Traffic Extension (RSVP-TE) is an addition to the RSVP protocol for establishing label switched paths (LSPs) in MPLS networks. The extended RSVP protocol supports the instantiation of explicitly routed LSPs, with or without resource reservations. It also supports smooth rerouting of LSPs, preemption and loop detection.
Standard Organization: IETF
Reference Document: RFC 3209

RSUP: Reliable SAP Update Protocol
Reliable SAP Update Protocol (RSUP) is a bandwidth-saving protocol developed by Cisco for propagating services information. RSUP allows routers to reliably send standard Novell SAP packets only when the routers detect a change in advertised services. RSUP can transport network information either in conjunction with or independently of the Enhanced IGRP routing function for IPX.
Standard Organization: Cisco

RTCP: RTP Control Protocol
The RTP control protocol (RTCP) is based on the periodic transmission of control packets to all participants in the session, using the same distribution mechanism as the data packets. The underlying protocol must provide multiplexing of the data and control packets, for example using separate port numbers with UDP.
Standard Organization: IETF
Reference Document: RFC 3350

RTMP: Real Time Messaging Protocol
Real Time Messaging Protocol (RTMP) is a proprietary protocol developed by Adobe Systems (formerly Macromedia) that is primarily used with Macromedia Flash Media Server to stream audio and video over the internet to the Macromedia Flash Player client. The default connection port is port 1935.
Standard Organization: Adobe

RTMP: Routing Table Maintenance Protocol
Routing Table Maintenance Protocol (RTMP), based on Routing Information Protocol (RIP), is a communication protocol used by AppleTalk to ensure that all routers on the network have consistent routing information. RTMP establishes and maintains the routing information that is required to route datagrams from any source socket to any destination socket in an AppleTalk network. Using RTMP, routers dynamically maintain routing tables to reflect changes in topology.
Standard Organization: Apple

RTP: Rapid Transport Protocol
Rapid Transport Protocol (RTP) provides pacing and error recovery for IBM APPN data as it crosses the APPN network. With RTP, error recovery and flow control are done end-to-end rather than at every node. RTP prevents congestion rather than reacts to it.
Standard Organization: IBM

RTP: Real-Time Transport Protocol
The Real-Time Transport Protocol (RTP) provides end-to-end delivery services for data with real-time characteristics, such as interactive audio and video or simulation data, over multicast or unicast network services. Applications typically run RTP on top of UDP to make use of its multiplexing and checksum services; both protocols contribute parts of the transport protocol functionality. However, RTP may be used with other suitable underlying network or transport protocols.
Standard Organization: IETF
Reference Document: RFC 3550

RTP: VINES Routing Table Protocol
VINES Routing Table Protocol (RTP), a network layer protocol in the VINES protocol stack, distributes network topology information. Routing update packets are broadcast periodically by both client and service nodes. These packets inform neighbors of a node's existence and also indicate whether the node is a client or a service node. In each routing update packet, service nodes include a list of all known networks and the cost factors associated with reaching those networks.
Standard Organization: Banyan

RTSE: Reliable Transfer Service Element
Reliable Transfer Service Element (RTSE), an ISO application layer protocol, provides for the reliable transfer of bulk data by transforming the data into a string of octets, then breaking the string into segments and handing each segment to the Presentation Layer for delivery. Checkpoints are established between segments. Through the services of the Presentation Layer, RTSE uses the activity management services of the Session Layer to manage the transfer of the collection of segments that make up the bulk data.
Standard Organization: ISO

RTSP: Real-Time Streaming Protocol
The Real-Time Streaming Protocol (RTSP) establishes and controls either a single or several time-synchronized streams of continuous media, such as audio and video. RTSP does not typically deliver the continuous streams itself, although interleaving of the continuous media stream with the control stream is possible. In other words, RTSP acts as a "network remote control" for multimedia servers. RTSP provides an extensible framework to enable controlled, on-demand delivery of real-time data, such as audio and video.
Standard Organization: IETF
Reference Document: RFC 2326

RUDP: Reliable UDP
Reliable UDP (RUDP) is a simple packet-based transport protocol which was intended as a reliable transport protocol to transport telephony signaling across IP networks. RUDP is designed to allow characteristics of each connection to be individually configured so that a number of protocols with different transport requirements can be implemented simultaneously not on the same platform.
Standard Organization: IETF
Reference Document: draft