R

radio frequency interference (RFI)

Interference from high-frequency electromagnetic waves emanating from electronic devices.

radio network controller (RNC)

Manages the radio part of the network in UMTS.

Randodm Early Detection (RED)

Gradual drop profile for a given class that is used for congestion avoidance. RED tries to anticipate incipient congestion and reacts by dropping a small percentage of packets from the head of the queue to ensure that a queue never becomes full.

rate limiting

See policing.

rate policing

See policing.

receive

A next hop for a static route that allows all matching packets to be sent to the Routing Engine for processing.

record route object (RRO)

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

recursive lookup

A 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.

regional Bell operating company (RBOC)

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

Register message

PIM message unicast by the first hop router to the 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.

reject

A 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 a firewall filter.

Remote Authentication Dial-In User Service (RADIUS)

Authentication method for validating users who attempt to access the router using Telnet.

rename

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

Request for Comments (RFC)

Internet standard specifications published by the Internet Engineering Task Force.

Rendezvous Point (RP)

For PIM-SM, a router acting as the root of the shared distribution tree.

Request message

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

resolve

A 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 (RSVP)

Resource reservation setup protocol designed to interact with integrated services on the Internet.

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 that indicates an error has occurred along an established LSP. The message is advertised downstream toward the egress router and it doesn’t remove any RSVP soft state from the network.

ResvTear message

RSVP message that indicates 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

Method used in a multicast routing domain to prevent forwarding loops.

reverse path multicasting (RPM)

Routing algorithm used by DVMRP to forward multicast traffic.

route filter

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

route flapping

Situation in which BGP systems send an excessive number of update messages to advertise and withdraw reachability of the same NLRI.

route identifier

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

route redistribution

A 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, configuring a group of routers into a cluster and having one system act 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

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

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 conected subnets as well as their metric values.

Router Priority

A numerical value assigned to an OSPF or an IS-IS interface that is used as the first criterion in electing the designated router or designated intermediate system, respectively.

routing domain

See Autonomous System (AS).

Routing Engine

Architectural 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 Information Base (RIB)

A logical data structure used by BGP to store routing information.

Routing Information Protocol (RIP)

Distance-vector Interior Gateway Protocol that makes routing decisions based on hop count.

routing instance

A collection of routing tables, interfaces, and routing protocol parameters. The set of interfaces belongs to the routing tables and the routing protocol parameters control the information in the routing tables.

routing protocol daemon (rpd)

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

routing table

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

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

A label-switched path that is dynamically established using RSVP Path and Resv messages.