RADIUS (Remote Authentication Dial-In User Service) is an authentication and accounting system used by many Internet Service Providers (ISPs).

When you dial in to the ISP you must enter your username and password. This information is passed to a RADIUS server, which checks that the information is correct, and then authorizes access to the ISP system.

RADIUS (Remote Authentication Dial-In User Service) is a client/server protocol and software that enables remote access servers to communicate with a central server to authenticate dial-in users and authorize their access to the requested system or service.

RADIUS allows a company to maintain user profiles in a central database that all remote servers can share.
For more information, please refer to this page http://www.networksorcery.com/enp/protocol/radius.htm

Remote access is the ability to get access to a computer or a network from a remote distance. In corporations, people at branch offices, telecommuters, and people who are traveling may need access to the corporation's network. Home users get access to the Internet through remote access to an Internet service provider (ISP).

Remote Access Server is a computer in a network that provides access to remote users via analog modem or ISDN connections. Including dial-up protocols and access control (authentication), it may be a regular file server with remote access software or a proprietary system.

Usually, Home users get access to the Internet through remote access to an Internet service provider (ISP). Dial-up connection through desktop, notebook, or handheld computer modem over regular telephone lines is a common method of remote access. Remote access is also possible using a dedicated line between a computer or a remote local area network and the "central" or main corporate local area network.

RIP (Routing Information Protocol) is a widely-used protocol for managing router information within a self-contained network such as a corporate local area network () or an interconnected group of such LANs. In other words, RIP specifies how routers exchange routing table information.

RIP is considered an effective solution for small homogeneous networks. The major alternative to RIP is the Open Shortest Path First Protocol (OSPF). For more information, please refer to this page http://www.networksorcery.com/enp/protocol/rip.htm.

Registered Jack-11 is a four- or six-wire connector used primarily to connect telephone equipment in the United States. RJ-11 connectors are also used to connect some types of local-area networks (LANs), although RJ-45 connectors are more common.

RJ45, an eight-wire connector used commonly to connect computers onto a local-area networks (LAN), especially Ethernets. RJ-45 connectors look similar to the ubiquitous RJ-11 connectors used for connecting telephone equipment, but they are somewhat wider.

Router is a device or, in some cases, software in a computer, that determines the next network point to which a packet should be forwarded toward its destination. In other words, A device that connects any number of LANs. Very little filtering of data is done through routers. Routers do not care about the type of data they handle.

RS-232 stands for Recommend Standard number 232, and approved by Electronic Industries Association (EIA). The serial ports on most computers use a subset of the RS-232C standard. The full RS-232C standard specifies a 25-pin "D" connector of which 22 pins are used. Most of these pins are not needed for normal PC communications, and indeed, most new PCs are equipped with male D type connectors having only 9 pins.

In 1987, the EIA changed the name to EIA-232-D. Many people, however, still refer to the standard as RSxxx. EIA has recently released new serial interface, RS-422 and RS-423. The RS-422 standards are designed to replace the older RS-232 standard, since they support higher data rates and greater immunity to electrical interference

RJ45 can be used for configuration and connecting the RS-232 serial devices. In other words, user can use RJ45 to DB9 console cable to manage RS-232 based serial devices. This connector is very specific and should be used only if DB9 is too big or for interfaces with machines using them. If needed, RJ-45 to DB9 adapters are easy to find.

RS422 is a Standard interfaces approved by the Electronic Industries Association (EIA), and designed for greater distances and higher Baud rates than RS232. In its simplest form, a pair of converters from RS232 to RS422 (and back again) can be used to form an "RS232 extension cord." Data rates of up to 100K bits / second and distances up to 4000 Ft. can be accommodated with RS422. RS422 is also specified for multi-drop (party-line) applications where only one driver is connected to, and transmits on, a "bus" of up to 10 receivers.

RS422 devices cannot be used to construct a truly multi-point network. A true multi-point network consists of multiple drivers and receivers connected on a single bus, where any node can transmit or receive data.

RS485 is an Electronics Industry Association (EIA) standard for multipoint communications. It supports several types of connectors, including DB-9 and DB-37. RS-485 is similar to RS-422 but can support more nodes per line RS485 meets the requirements for a truly multi-point communications network, and the standard specifies up to 32 drivers and 32 receivers on a single (2-wire) bus. With the introduction of "automatic" repeaters and high-impedance drivers / receivers this "limitation" can be extended to hundreds (or even thousands) of nodes on a network.

The RS-485 and RS-422 standards have much in common, and are often confused for that reason. RS-485, which specifies bi-directional, half-duplex data transmission, is the only EIA/TIA standard that allows multiple receivers and drivers in "bus" configurations RS-422, on the other hand, specifies a single, unidirectional driver with multiple receivers.

The Ready To Send (RTS) and Clear To Send (CTS) lines for the RS-232 serial interface were originally intended as handshaking signals between a DTE device (computer, printer, and so forth) and a DCE device (almost always a modem). This section describes unidirectional handshaking between two DTE devices: a computer and a printer. The computer asserts its RTS (Ready To Send) line when it is ready to send data to the printer. The printer asserts its RTS when it was ready to receive data.

For modems, RTS/CTS flow control is the preferred method as it is more efficient and reliable.

In RTS/CTS flow control, the computer and the modem use the RTS and CTS lines respectively to control the flow of data (for example, when the modem's buffer is full). For modems, RTS/CTS flow control is the preferred method as it is more efficient and reliable