Radar is a set of advanced, intelligent, Wireless-Intrusion-Detection-Service-Wireless-Intrusion-Prevention-Service (WIDS-WIPS) features that are integrated into the Wireless Controller and its access points (APs). Radar provides a basic solution for discovering unauthorized devices within the wireless coverage area. Radar performs basic RF network analysis to identify unmanaged APs and personal ad-hoc networks. The Radar feature set includes: intrusion detection, prevention and interference detection.


Remote Authentication Dial In User Service. RADIUS 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. It provides better security, allowing a company to set up a policy that can be applied at a single administered network point. With RADIUS, you can track usage for billing and for keeping network statistics.


Reverse ARP. Using this protocol, a physical device requests to learn its IP address from a gateway server's ARP table. When a new device is set up, its RARP client program requests its IP address from the RARP server on the router. Assuming that an entry has been set up in the router table, the RARP server will return the IP address to the machine which can store it for future use.

rate limiting

In QoS, rate limiting is the process of restricting traffic to a peak rate (PR). For more information, see rate limiting and rate shaping in the ExtremeXOS 21.1 User Guide.

rate shaping

In QoS, rate shaping is the process of reshaping traffic throughput to give preference to higher priority traffic or to buffer traffic until forwarding resources become available. For more information, see rate limiting and rate shaping in the ExtremeXOS 21.1 User Guide.


Radio Frequency. A frequency in the electromagnetic spectrum associated with radio wave propagation. When an RF current is supplied to an antenna, an electromagnetic field is created that can propagate through space. These frequencies in the electromagnetic spectrum range from Ultra-low frequency (ULF):0-3 Hz to Extremely high frequency (EHF): 30 GHz–300 GHz. The middle ranges are: Low frequency (LF): 30 kHz–300 kHz; Medium frequency (MF): 300 kHz–3 MHz; High frequency (HF): 3 MHz–30 MHz; Very high frequency (VHF): 30 MHz–300 MHz; and Ultra-high frequency (UHF): 300 MHz–3 GHz.


Request for Comment. The IETF RFCs describe the definitions and parameters for networking. The RFCs are catalogued and maintained on the IETF RFC website: www.ietf.org/rfc.html.


Ridgeline is an Extreme Networks-proprietary graphical user interface (GUI) network management system. The name was changed from EPICenter to Ridgeline in 2011.


Routing Information Protocol. This IGP vector-distance routing protocol is part of the TCP/IP suite and maintains tables of all known destinations and the number of hops required to reach each. Using RIP, routers periodically exchange entire routing tables. RIP is suitable for use only as an IGP.


RIP next generation. RIPng is one of the routing protocols used with IPv6 and is similar to RIP.


Remote monitoring. RMON is a standardized method to make switch and router information available to remote monitoring applications. It is an SNMP network management protocol that allows network information to be gathered remotely. RMON collects statistics and enables a management station to monitor network devices from a central location. It provides multivendor interoperability between monitoring devices and management stations. RMON is described in several RFCs (among them IETF RFC 1757 and RFC 2201).

Network administrators use RMON to monitor, analyze, and troubleshoot the network. A software agent can gather the information for presentation to the network administrator with a graphical user interface (GUI). The administrator can find out how much bandwidth each user is using and what web sites are being accessed; you can also set alarms to be informed of potential network problems.


In 802.11, roaming occurs when a wireless device (a station) moves from one Access Point to another (or BSS to another) in the same Extended Service Set (ESS) -identified by its SSID.

root bridge

In STP, the root bridge is the bridge with the best bridge identifier selected to be the root bridge. The network has only one root bridge. The root bridge is the only bridge in the network that does not have a root port.

root port

In STP, the root port provides the shortest path to the root bridge. All bridges except the root bridge contain one root port.

route aggregation

In BGP, you can combine the characteristics of several routes so they are advertised as a single route, which reduces the size of the routing tables.

route flapping

A route is flapping when it is repeatedly available, then unavailable, then available, then unavailable. In the ExtremeXOS BGP implementation, you can minimize the route flapping using the route flap dampening feature.

route reflector

In BGP, you can configure the routers within an AS such that a single router serves as a central routing point for the entire AS.

routing confederation

In BGP, you can configure a fully meshed autonomous system into several sub-ASs and group these sub-ASs into a routing confederation. Routing confederations help with the scalability of BGP.


Reverse Polarity-Subminiature version A, a type of connector used with wireless antennas.


Robust Security Network. A new standard within IEEE 802.11 to provide security and privacy mechanisms. The RSN (and related TSN) both specify IEEE 802.1x authentication with Extensible Authentication Protocol (EAP).


RSSI received signal strength indication (in 802.11 standard).


RTS request to send, CTS clear to send (in 802.11 standard).


Rapid Spanning Tree Protocol. RSTP, described in IEEE 802.1w, is an enhanced version of STP that provides faster convergence. The Extreme Networks implementation of RSTP allows seamless interoperability with legacy STP.