Cisco Systems Cisco IOS XR Group of software components installed on the router, SDH frames, GL-8

Glossary

OSI

OSPF

Open Systems Interconnection. International standardization program created by ISO and ITU-T to develop standards for data networking that facilitate multivendor equipment interoperability.

Open Shortest Path First. Link-state, hierarchical Interior Gateway Protocol (IGP) routing algorithm proposed as a successor to Routing Information Protocol (RIP) in the Internet community. OSPF features include least-cost routing, multipath routing, and load balancing. OSPF was derived from an early version of the Intermediate System-to-Intermediate System (IS-IS) protocol. See also IGP and RIP.

P

package	A group of software components installed on the router.
packet	Logical grouping of information that includes a header containing control information and (usually)
	user data. Packets most often are used to refer to network layer units of data.
Packet over	POS. Packet over SONET/SDH enables core routers to send native IP packets directly over SONET or
SONET/SDH	SDH frames.
PAP	Password Authentication Protocol. Authentication protocol that allows PPP peers to authenticate one
	another. The remote router attempting to connect to the local router is required to send an authentication
	request. Unlike Challenge Handshake Authentication Protocol (CHAP), PAP passes the password and
	the hostname or username in the clear (unencrypted). PAP does not itself prevent unauthorized access
	but merely identifies the remote end. The router or access server then determines whether that user is
	allowed access. PAP is supported only on PPP lines. See also PPP.

PCMCIA

PIE

Personal Computer Memory Card International Association. Standard for credit card-size memory or I/O device.

package installation envelope. An installable software file with the suffix pie. A PIE may be a package or a Software Maintenance Upgrade (SMU). A PIE is used to deliver Cisco IOS XR software. A PIE may contain a single component, group of components (called a package), or set of packages. When a PIE contains more than one component, it is called a “Composite PIE.”

PLIM	Physical layer interface module. Provides the physical interface for a line card. Also handles
	media-specific functions, such as framing, clock recovery, channelization, and optical signaling for line
	interfaces connecting to a Cisco CRS-1 router.
PM	performance monitoring. Provides a variety of automatic functions to aid in the maintenance and
	operation of the network. PM is continuous, in-service monitoring of transmission quality that uses
	software-provisionable performance parameters. Performance parameters are measured for all four
	layers of the SONET signal: physical, section, line, and STS path.
POS	Packet over SONET/SDH. POS enables core routers to send native IP packets directly over
	Synchronous Optical Network (SONET) or Synchronous Digital Hierarchy (SDH) frames.

	Cisco IOS XR Getting Started Guide
GL-8	OL-10957-02