CCNA Cisco Certified Network Associate Study Guide - FTP Server

Glossary 699
priority queueing A routing function in which frames temporarily placed
in an interface output queue are assigned priorities based on traits such as
packet size or type of interface.
process switching As a packet arrives on a router to be forwarded, it’s
copied to the router’s process buffer, and the router performs a lookup
on the Layer 3 address. Using the route table, an exit interface is associated
with the destination address. The processor forwards the packet with the
added new information to the exit interface, while the router initializes the
fast-switching cache. Subsequent packets bound for the same destination
address follow the same path as the first packet.
PROM programmable read-only memory: ROM that is programmable
only once, using special equipment. Compare with: EPROM.
propagation delay The time it takes data to traverse a network from its
source to its destination.
protocol In networking, the specification of a set of rules for a particular
type of communication. The term is also used to refer to the software that
implements a protocol.
protocol stack A collection of related protocols.
PSE Packet Switch Exchange: The X.25 term for a switch.
PSN packet-switched network: Any network that uses packet-switching
technology. Also known as packet-switched data network (PSDN). See also:
packet switching.
PSTN Public Switched Telephone Network: Colloquially referred to as
“plain old telephone service” (POTS). A term that describes the assortment
of telephone networks and services available globally.
PVC permanent virtual circuit: In a Frame-Relay network, a logical connection,
defined in software, that is maintained permanently. Compare with:
SVC. See also: virtual circuit.
PVP permanent virtual path: A virtual path made up of PVCs. See
also: PVC.