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Glossary

route summarization

In various routing protocols, such as OSPF, EIGRP,

and IS-IS, the consolidation of publicized subnetwork addresses so that a
single summary route is advertised to other areas by an area border router.

router

A network-layer mechanism, either software or hardware, using

one or more metrics to decide on the best path to use for transmission of net-
work traffic. Sending packets between networks by routers is based on the
information provided on network layers. Historically, this device has some-
times been called a gateway.

routing

The process of forwarding logically addressed packets from their

local subnetwork toward their ultimate destination. In large networks, the
numerous intermediary destinations a packet might travel before reaching its
destination can make routing very complex.

routing domain

Any collection of end systems and intermediate sys-

tems that operate under an identical set of administrative rules. Every
routing domain contains one or several areas, all individually given a
certain area address.

routing metric

Any value that is used by routing algorithms to determine

whether one route is superior to another. Metrics include such information
as bandwidth, delay, hop count, path cost, load, MTU, reliability, and com-
munication cost. Only the best possible routes are stored in the routing table,
while all other information may be stored in link-state or topological data-
bases. See also: cost.

routing protocol

Any protocol that defines algorithms to be used for

updating routing tables between routers. Examples include IGRP, RIP,
and OSPF.

routing table

A table kept in a router or other internetworking mecha-

nism that maintains a record of only the best possible routes to certain
network destinations and the metrics associated with those routes.

Route Processor: Also known as a supervisory processor, a module on

Cisco 7000 series routers that holds the CPU, system software, and most of
the memory components used in the router.

RSP

Route/Switch Processor: A processor module combining the functions

of RP and SP used in Cisco 7500 series routers. See also: RP and SP.

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