N-P

network address translation (NAT)

A mechanism used for translating between local IP addresses and global IP addresses for extending the IP address space.

network byte order

Similar to the big-endian method of representation, in which the transmission of integers across the network begins with the most significant byte.

network prefix

Each IP address is composed of a network prefix and a host prefix. The network prefix identifies the network that the node with this IP address belongs to.

network processor

A programmable processor which is optimized to process packets at a very rapid rate. The instruction set handles only network functions. Programmers can write code using this optimized instruction set and download to the processor for handling packets.

NIC

Network Interface Card. Another name for an add-on adapter card for networking purposes, e.g., an Ethernet NIC for a PC.

node

A term used to describe a communicating entity on a network. A host is an end node, while a router could be a network node or routing node.

non-volatile RAM (NVRAM)

Small IC powered by a battery, used to store system parameters.

NP

Network Processor.

NPU

Network Processor Unit. Another name for a network processor.

Nucleus

A real time operating system from Mentor Graphics.

OSAL

Operating System Adaptation Layer. Used to isolate the application from the underlying operating system. An application makes only OSAL calls, so it can be ported to multiple OSes as long as there is an OSAL for that OS.

OSE™

A real-time operating system from OSE Systems. It relies primarily on message passing for its IPC.

OSI

Open Systems Interconnect. The seven- layer model for networking specified by the ISO.

OSPF

Open Shortest Path First. A routing protocol based on a link-state algorithm, in which every node constructs a topography and uses it for forwarding.

packet

The unit of transmission in a packet- switching network. The complete message is divided and sent as individual packets through a network.

packet switch

A device which forwards or switches packets through a network.

payload

The data carried in a packet.

PBX

Private Branch Exchange. A circuit- switching device which is used to switch calls within the same premises.

PCI

Peripheral Component Interconnect. A bus to interconnect processors and peripherals.

PDU

Protocol Data Unit. A term used to describe a packet.

PDU preprocessing

A set of operations in which a PDU is validated, verified and classified so that the appropriate event can be sent to a protocol state machine.

peer

The corresponding node for the other end of the communication. The peers communicate with each other using a protocol.

PHY

A term used to describe the physical layer device or chip interfacing to the line.

physical interface

A physical port in the communications system.

PICB

Protocol Interface Control Block.

PICMG

PCI Industrial Computer Manufacturers Group (www.picmg.org).

PICMG 2.16

The standard from PICMG which uses Ethernet in the backplane for switching traffic between the cards in the PICMG chassis.

PIM

Protocol Independent Multicast. A multicast routing protocol specified by the IETF.

ping

Packet Internet Groper. A mechanism whereby an ICMP echo request packet (ping request) is sent from one TCP/IP communications device to another to verify its connectivity and status. The receiver of the ping request sends an ICMP echo reply (ping response) to the sender.

PMC

PCI Mezzanine Card. A card with a processor and/or other peripherals for adding functionality to an embedded system.

polling

A method of programming in which the processor repeatedly checks for a specific event or events.

POSIX

Portable Operating System Interface. A standard environment for enabling the portability of applications software. Originally a work of the Open Group, it has been adopted by the IEEE and ISO.

POTS

Plain Old Telephone Service. Used to describe the 'traditional' telephone network.

PPP

Point to Point Protocol. A protocol specified by the IETF for transmission of Layer 2/3/4 packets over a serial link.

predicate

A parameter in a state event table used as an additional qualifier for an action routine.

process

An operating system abstraction that allows different operations to take place concurrently. Memory protection is typically enforced between processes.

product requirements document

A document prepared by Marketing to provide specifications requirements for the product.

protocol

A set of messages and rules for communicating between peer entities. Protocols are usually specified in standard specifications.

protocol stack or protocol suite

The software implementation of a protocol.

pseudo header

A header that is used only in calculating the TCP or UDP checksum.

PVC

Permanent Virtual Circuit. A virtual circuit that is set up manually and stays on.



Designing Embedded Communications Software
Designing Embedded Communications Software
ISBN: 157820125X
EAN: 2147483647
Year: 2003
Pages: 126
Authors: T. Sridhar

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