Glossary
GL-10
Cisco IOS XR Getting Started Guide
OL-10957-02
routing metric A routing algorithm determines that one route is better than another. This information is stored in
routing tables. Metrics include bandwidth, communication cost, delay, hop count, load, MTU, path
cost, and reliability. Sometimes referred to simply as a metric. See also algorithm.
routing protocol Protocol that accomplishes routing through the implementation o f a specific routing algorithm.
Examples of routing protocols include BGP, OSPF, and IS-IS.
routing table Table stored in a router or some other internetworking device that keeps track of routes to particular
network destinations and, in some cases, metrics associated with those routes.
RP route processor. Cards that contain run-control software on the router. Two RPs are installed as a
redundant pair in dedicated slots in the front of each line card chassis.
RPF Reverse Path Forw arding. Multicasting technique in which a multicast datagram is forwarded from all but
the receiving interface if the receiving interface is the one used to forward unicast datagrams to the source
of the multicast datagram.
RSVP Resource Reservation Protocol. Protocol that supports the reservation of resource s across an IP
network. Applications running on IP end systems can use RSVP to indicate to other nodes the nature
(bandwidth, jitter, maximum burst, and so on) of the packet streams they want to receive. RSVP
depends on IPv6. Also known as Resource Reservation Setup Protocol. See also IPv6.
running
configuration
The router configuration currently in effect. Although the user can save multiple versions of the router
configuration for future reference, only one copy of the running configurati on exists in the router at any
given time.
Rx The receiver end of a fabric link. All links are unidirectional. See also Tx.
S
SCFC shelf controller/fan controller. Combines shelf controller function and fan c ontroller function on one
card. Two are installed in each fabric chassis.
SDH Synchronous Digital Hierarchy. European standard that defines a set of rate and format standards that
are sent using optical signals over fiber. SDH is similar to SONET, with a basic SDH rate of
155.52 Mbps, designated at STM-1.
SDR secure domain router. A collection of line cards and route processors that form a complete router. Each
router contains its own instance of dynamic routing, IP stack, system data base, interface manager, and
event notification system.
SDRAM synchronous dynamic random access memory. A form of dynamic RAM that adds a separate clock
signal to the control signals.
shelf controller The hardware component that manages the configuration and health of a fabric chassis within the
Cisco CRS-1 router.
shelf manager The shelf manager proce ss runs on a router or switch, doing platform-dependent functi ons, including
handling OIR events. Shelf manager is formerly called platform manager.
SMU Software Maintenance Upgrade. A “point fix” for a critical problem. SMUs are delivered as PIE files
and are used to update software packages.