The unit of data sent across a packet switching network. The term is used loosely. While some Internet literature uses it to refer specifically to data sent across a physical network, other literature views the Internet as a packet switching network and describes IP datagrams as packets.
PAD
Packet Assembler/Disassembler.
PAGE
Program for the Advancement of Geosciences Education
PAgP
Port Aggregation Protocol
PAM
Pluggable Authentication Modules - a software library that does authentication. NETS usus PAM on servers to enable use of one-time-passwords for login, ssh, etc.
PAM
Port Adapter Modules (Cisco)
PAM
Port to Application Mapping
PAM
Project Accounting Manager
PAM
Pulse Amplitude Modulation
PAN
Personal Area Network
PAP
Password Authentication Protocol
PAR
Project Authorization Request
PAT
Port Address Translation
PBR
Policy-Based Routing
PBX
Private Branch eXchange
PC
President's Council
PCI
Peripheral Component Interconnect; Protocol Control Information
PCM
Parallel Climate Model
PCM
Pulse Code Modulation
PCR
Peak Cell Rate
PDIO
Planning, Design, Implementation, Operation
PDLM
Protocol Description Language Module
PDQ
Position Description Questionnaire
PDU
Power Distribution Unit (a device) or Protocol Data Unit (a network data packet).
PDU
Protocol Data Unit
PERT
Program Evaluation and Review Technique
PFC
Policy Feature Card, a daughtercard card that mounts on Supervisor 720 modules in Cisco Catalyst switches. In Sup 720 modules, the PFC and MSFC cards are not optional. The PFCaccelerates layer 2 and 3 switching and routing.
PFE
Packet Forwarding Engine (Juniper)
PHB
Per-Hop Behavior
physical address
See MAC-level address.
PI
Principal Investigator
PIC
Physical Interface Card (Juniper)
PIM
Protocol Independent Multicast. A multicast routing architecture that allows the addition of IP multicast routing on existing IP networks.
ping
Packet internet groper. A program used to test reachability of destinations by sending an ICMP echo request and waiting for a reply. The term is used as a verb: Ping host X to see if it is up!
PKCS
Public Key Cryptography Standard
PKI
Public Key Infrastructure
PLCP
Physical Layer Convergence Procedure
PLMN
Public Land Mobile Net
PMEL
Pacific Marine Environmental Laboratory (NOAA)
PO
Purchase Order
PoE
Power over Ethernet
POP
Point of Presence
POP
Post Office Protocol
port
The abstraction used by Internet transport protocols to distinguish among multiple simultaneous connections to a single destination host.
POS
Packet Over SONET
POST
Power On Self Test
PowerHub
The name of a type of hub manufactured by Alantec. Alantec PowerHubs were once used at NCAR.
POWR
POWeR outage call list, a phone list used when a major power or network outage prevents sending of UCAR status messages to users via email.
PPK
Public Private Key
PPP
Point-to-Point Protocol. The successor to SLIP, PPP provides router-to-router and host-to-network connections over both synchronous and asynchronous circuits.
A formal description of message formats and the rules two computers must follow to exchange those messages. Protocols can describe low-level details of machine-to-machine interfaces (e.g., the order in which bits and bytes are sent across a wire) or high-level exchanges between programs (e.g., the way in which two programs transfer a file). Some protocols are IP, IPX, DECnet, AppleTalk, EtherTalk, SNMP, SMTP.
Proxim
The company that makes the Proxim/Tsunami radio units (ml-330-wm1-wb.ucar.edu and fl3-3068-wm1-wb.ucar.edu) that UCAR uses to connect the Mesa Lab and Foothills Lab sites. The link backs up fiber that connects ML and FL.
proxy ARP
The technique in which one machine, usually a router, answers ARP requests intended for another machine. By "faking" its identity, the router accepts responsibility for routing packets to the "real" destination.
proxy
The mechanism whereby one system "fronts for" another system in responding to protocol requests.
Performance Systems International, Inc. PSI wrote the network monitoring software once used by NCAR
PSTN
Public Switched Telephone Network
PTCM
PCM/CSM Transition Model
PTO
Paid Time Off
PVC
Permanent Virtual Circuit. A term used in ATM and Frame Relay networks to specify a permanent (exists whether data is flowing or not) connection between two entities on a network.
