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R

RA — Registration authority. A trusted third-party organization that acts on behalf of a certificate authority (CA) to verify the identity of a digital certificate user.

radio frequency interference — See RFI.

radio network controller — See RNC.

RADIUS — Remote Authentication Dial-In User Service. An authentication method for validating users who attempt to access the router using telnet.

random early detection — See RED.

Rapid Spanning Tree Protocol — See RSTP.

rate limiting — See policing.

RBOC — (Pronounced “are-bock”) Regional Bell operating company. Regional telephone companies formed as a result of the divestiture of the Bell System.

RC2, RC4, RC5 — RSA codes. A family of proprietary (RSA Data Security, Inc.) encryption schemes often used in Web browsers and servers. These codes use variable-length keys up to 2048 bits.

RDBMS — Relational database management system. A system that presents data in a tabular form with a means of manipulating the tabular data with relational operators.

RDM — Russian-dolls bandwidth allocation model. An allocation model that makes efficient use of bandwidth by allowing the class types to share bandwidth. RDM is defined in the Internet draft draft-ietf-tewg-diff-te-russian-03.txt, Russian Dolls Bandwidth Constraints Model for Diff-Serv-aware MPLS Traffic Engineering.

Real-Time Performance Monitoring — See RPM.

Real-Time Transport Protocol — See RTP.

receive — Next hop for a static route that allows all matching packets to be sent to the Routing Engine for processing.

record route object — See RRO.

recursive lookup — Method of consulting the routing table to locate the actual physical next hop for a route when the supplied next hop is not directly connected.

RED — Random early detection. Gradual drop profile for a given class that is used for congestion avoidance. RED tries to anticipate incipient congestion by dropping a small percentage of packets from the head of the queue to ensure that a queue never actually becomes congested.

refresh reduction — In RSVP, an extension that addresses the problems of scaling, reliability, and latency when Refresh messages are used to cover message loss.

Regional Bell operating company — See RBOC.

Register message — PIM message unicast by the first–hop router to the rendezvous point (RP) that contains the multicast packets from the source encapsulated within its data field.

Register Stop message — PIM message sent by the RP to the first–hop router to halt the sending of encapsulated multicast packets.

registration authority — See RA.

reject — Next hop for a configured route that drops all matching packets from the network and returns an ICMP message to the source IP address. Also used as an action in a routing policy or firewall filter.

relational database management system — See RDBMS.

Remote Authentication Dial-In User Service — See RADIUS.

remote monitoring — See RMON.

remote procedure call — See RPC.

rename — JUNOS software command that allows a user to change the name of a routing policy, firewall filter, or any other variable character string defined in the router configuration.

rendezvous point — See RP.

Request for Comments — See RFC.

Request message — RIP message used by a router to ask for all or part of the routing table from a neighbor.

resolve — Next hop for a static route that allows the router to perform a recursive lookup to locate the physical next hop for the route.

Resource Reservation Protocol — See RSVP.

Response message — RIP message used to advertise routing information into a network.

result cell — JUNOS software data structure generated by the Internet Processor ASIC after performing a forwarding table lookup.

ResvConf message — RSVP message that allows the egress router to receive an explicit confirmation message from a neighbor that its Resv message was received.

ResvErr message — RSVP message indicating that an error has occurred along an established LSP. The message is advertised downstream toward the egress router and it does not remove any RSVP soft state from the network.

ResvTear message — RSVP message indicating that the established LSP and its associated soft state should be removed by the network. The message is advertised upstream toward the ingress router.

reverse-path forwarding — See RPF.

reverse-path multicasting — See RPM.

revert timer — For SONET Automatic Protection Switching (APS), a timer that specifies the amount of time (in seconds) to wait after the working circuit has become functional before making the working circuit active again.

rewrite rules — Set the appropriate class–of–service (CoS) bits in an outgoing packet. This allows the next downstream router to classify the packet into the appropriate service group.

RFC — Request for Comments. Internet standard specifications published by the Internet Engineering Task Force (IETF).

RFI — Radio frequency interface. Interference from high-frequency electromagnetic waves emanating from electronic devices.

RIB — Routing information base. A logical data structure used by BGP to store routing information. See also routing table.

RID — Router ID. An IP address used by a router to uniquely identify itself to a routing protocol. This address may not be equal to a configured interface address.

RIP — Routing Information Protocol. Used in IPv4 networks, a distance-vector interior gateway protocol that makes routing decisions based on hop count.

RIPng — Routing Information Protocol next generation. Used in IPv6 networks, a distance-vector interior gateway protocol that makes routing decisions based on hop count.

RMON — Remote monitoring. A standard MIB that defines current and historical MAC-layer statistics and control objects, allowing you to capture real-time information across the entire network. This allows you to detect, isolate, diagnose, and report potential and actual network problems.

RNC — Radio network controller. Manages the radio part of the network in UMTS.

Root System Domain — A pair of redundant Routing Engines on a Juniper Networks router connected to the switch fabric on the Juniper Control System (JCS) platform. The configuration on the Routing Engines on the Juniper Networks router provides the RSD identification and the configuration of up to eight Protected System Domains (PSDs).

route distinguisher — 6-byte value identifying a VPN that is prefixed to an IPv4 address to create a unique IPv4 address. The new address is part of the VPN IPv4 address family, which is a BGP address family added as an extension to the BGP protocol. It allows you to configure private addresses within the VPN by preventing overlap with the private addresses in other VPNs.

route filter — JUNOS software syntax used in a routing policy to match an individual route or a group of routes.

route flapping — Condition of network instability where a route is announced and withdrawn repeatedly, often as the result of an intermittently failing link.

route identifier — IP address of the router from which a BGP, IGP, or OSPF packet originated.

route redistribution — Method of placing learned routes from one protocol into another protocol operating on the same router. The JUNOS software accomplishes this with a routing policy.

route reflection — In BGP, the configuration of a group of routers into a cluster in which one system acts as a route reflector, redistributing routes from outside the cluster to all routers in the cluster. Routers in a cluster do not need to be fully meshed.

router ID — See RID.

router-link advertisement — OSPF link-state advertisement flooded throughout a single area by all routers to describe the state and cost of the router’s links to the area.

router LSA — OSPF link-state advertisement sent by each router in the network. It describes the local router’s connected subnets and their metric values.

router priority — Numerical value assigned to an OPSF or IS-IS interface that is used as the first criterion in electing the designated router or designated intermediate system, respectively.

routing domain — See AS.

Routing Engine — Portion of the router that handles all routing protocol processes, as well as other software processes that control the router’s interfaces, some of the chassis components, system management, and user access to the router.

routing gateway — A firewall, network address translation (NAT) router, or other routing device used as a customer premises (CPE) terminator in the home, office, or local point of presence (POP).

routing information base — See RIB.

Routing Information Protocol — See RIP.

Routing Information Protocol next generation — See RIPng.

routing instance — Collection of routing tables, interfaces, and routing protocol parameters. The set of interfaces is contained in the routing tables, and the routing protocol parameters control the information in the routing tables.

routing matrix — Terabit routing system interconnecting up to four T640 routing nodes and a TX Matrix platform to deliver up to 2.56 terabits per second (Tbps) of subscriber switching capacity.

routing protocol daemon — See rpd.

routing table — Common database of routes learned from one or more routing protocols. All routes are maintained by the JUNOS routing protocol process.

RP — Rendezvous point. For PIM sparse mode, a core router acting as the root of the distribution tree in a shared tree.

RPC — Remote procedure call. A type of protocol that allows a computer program running on one computer to cause a function on another computer to be executed without explicitly coding the details for this interaction.

rpd — JUNOS software routing protocol process (daemon). A user-level background process responsible for starting, managing, and stopping the routing protocols on a Juniper Networks router.

RPF — Reverse path forwarding. An algorithm that checks the unicast routing table to determine whether there is a shortest path back to the source address of the incoming multicast packet. Unicast RPF helps determine the source of denial-of-service attacks and rejects packets from unexpected source addresses.

RPM — RPM can be either of the following:

Reverse-path multicasting. Routing algorithm used by Distance Vector Multicast Routing Protocol (DVMRP) to forward multicast traffic.
Real-Time Performance Monitoring. A tool for creating active probes to track and monitor traffic.

RRO — Record route object. An RSVP message object that notes the IP address of each router along the path of an LSP.

RSA codes — See RC2, RC4, RC5.

RSD — See Root System Domain

RSTP — Rapid Spanning Tree Protocol. A spanning-tree protocol used to prevent loops in bridge configurations. RSTP is not aware of VLANs and blocks ports at the physical level. See also MSTP.

RSVP — Resource Reservation Protocol. A signaling protocol that establishes a session between two routers to transport a specific traffic flow.

RSVP Path message — RSVP message sent by the ingress router downstream toward the egress router. It begins the establishment of a soft state database for a particular label-switched path.

RSVP Resv message — RSVP message sent by the egress router upstream toward the ingress router. It completes the establishment of the soft state database for a particular label-switched path.

RSVP signaled LSP — Label-switched path that is dynamically established using RSVP Path and Resv messages.

RSVP-TE — RSVP-traffic engineering; RSVP with traffic engineering extensions as defined by RFC 3209. These extensions allow RSVP to establish label-switched paths (LSPs) in MPLS networks. See also MPLS, RSVP.

RTP — Real-Time Transport Protocol. An Internet protocol that provides mechanisms for the transmission of real-time data, such as audio, video, or voice, over IP networks. Compressed RTP is used for VoIP traffic.

RTVBR — Real-time variable bit rate. For ATM2 intelligent queuing (IQ) interfaces, data that is serviced at a higher priority rate than other VBR data. RTVBR is suitable for carrying packetized video and audio. RTVBR provides better congestion control and latency guarantees than non-real-time VBR.

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