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Peer-to-Peer (P2P) is where devices link to each other without an intermediary and either device can initiate communications.


Package Management

Package Management is feature wherein a device (such as a NAS) can download multiple packages/files at once and integrate them automatically in the device as ready-to-use applications.



A unit of data transmitted over a network.


Packet Cable MTA

A Packet Cable Multimedia Terminal Adapter (MTA) network uses IP technology to allow various multimedia services such as VoIP and interactive gaming to function over a cable network.


Packet Filter

A filter that scans packets and decides whether to let them through or not.


Packet Transfer Mode (PTM)

Packet Transfer Mode (PTM) is packet-oriented and supported by the VDSL2 standard. In PTM, packets are encapsulated directly in the High-level Data Link Control (HDLC) frames. It is designed to provide a low-overhead, transparent way of transporting pack



PPPoA-to-PPPoE (PAE) allows a system to translate PPPoA packets to PPPoE packets (and vice versa) to allow communication between CPE clients and an access concentrator (such as a BRAS) on the network.



PAgP (Port Aggregation Protocol) is used to set up a logical aggregation of Ethernet ports automatically.


Pan and Scan

When you display video that is a wider aspect ratio than the television (displaying 16:9 ratio video on a 4:3 ratio television for example), pan and scan aspect ratio cuts off the sides of the wider aspect video and just shows the center portion.



A security protocol that requires users to enter a password before accessing a secure system. The user’s name and password are sent over the wire to a server where they are compared with a database of user account names and passwords.


Parfocal lens

A parfocal lens is a lens that stays in focus when magnification/focal length is changed. There is inevitably some amount of focus error, but small enough to be considered insignificant.


Parity (RAID)

RAID parity is a way to allow data recovery in the event of disk failure in a RAID volume. If a single disk in the volume goes down, then data can be reconstructed from parity bits stored in the other disks in the volume. As data does not have to be duplicated in order to be restored, storage space is maximized. See also RAID, Volume, Mirroring.


Passive Infrared Receiver

A Passive Infrared Receiver measures temperature changes in an area.



A passphrase is a string of text used for automatic WEP key generation on wireless client



Password Cracker

A program that uses a dictionary of words, phrases, names, etc. to guess a password.


Password Encryption

A system of encrypting electronic files using a single key or password. Anyone who knows the password can decrypt the file.


Password Shadowing

The encrypted password is not visible in the password file but stored in a shadow file that is only readable by root. This prevents brute force attacks on the encrypted field to guess the password.


Path Cost

In RSTP (or STP), path cost is the cost of transmitting a frame onto a LAN through that port. It is assigned according to the speed of the link to which a port is attached. The slower the media, the higher the cost.


Pattern Matching

Pattern matching identifies malicious code strings in a single packet.



A subscriber-owned telecommunications exchange that usually includes access to the public switched network. It may also be a private telephone switchboard that provides on-premises dial service and may provide connections to local and trunked communications networks.



Pulse Code Modulation measures analog signal amplitudes at regular time intervals and converts them into bits.



In ATM, the Peak Cell Rate is the maximum rate at which the sender can send cells. This parameter may be set lower (but not higher) than the maximum line speed. 1 ATM cell is 53 bytes (424 bits), so a maximum speed of 832Kbps gives a maximum PCR of 1962 cells/sec. This rate is not guaranteed because it depends on the line speed.


Personal Digital Assistant. A handheld computer that provides a calendar and organizer for personal information. A PDA normally contains at least one database with names and addresses, to-do lists and a notepad.



PEAP (Protected Extensible Authentication Protocol) is an authentication protocol of IEEE 802.1x that uses certificates. A protocol for transmitting authentication data, including passwords over 802.11 wireless networks.


Peers (BitTorrent)

This is a term used when downloading content from the Internet using BitTorrent protocol. Peers refer the total number of computers that are "sharing" the file that you are downloading.



Gaining access to computers or networks by bypassing security programs and passwords.



The PER is the percentage of data packets transmitted across a network but not successfully received.


Per-VLAN Isolation

Per-VLAN isolation blocks an IP DSLAMs DSL subscribers in a specific VLAN from sending traffic directly to each other.


Periodic Ranging

In WiMAX, a mobile station sends this request in order to update and track variations in timing offset.



Perfect Forward Secrecy is an IPSec keying method that uses a brand new key for each new IPSec SA setup. The keys are created by new key exchanges, see Diffie-Hellman.



Per-Hop Behavior is the forwarding treatment that each packet gets across a DiffServ network.



Phishing is where fraudsters send e-mail claiming to be from a well-known enterprise in an attempt to steal private information for use in identity theft. See also identity theft.



Breaking into phone or other communication systems.



A Personal Identification Number (PIN) is a numeric password used to identify oneself and gain access to an application.



In cellular telephony, the PIN2 code operates in the same way as the SIM PIN, but protects settings related to the cellular service provider, such as fixed dialing and call barring.



Ping (Packet Internet Groper) is a computer network utility used to test if a particular host is reachable across the IP network. Ping works by sending echo request packets to a target host and waiting for echo response replies.


Ping Attack

An attack that slows down the network until it is unusable. The attacker sends a "ping" command to the network repeatedly to slow it down. See also Denial of Service.


Ping Of Death

Ping of Death uses a "ping" utility to create and send an IP packet that exceeds the maximum 65,536 bytes of data allowed by the IP specification. This may cause systems to crash, hang or reboot.



The Peak Information Rate (PIR) is the maximum bandwidth allowed for the incoming traffic flow on a port when there is no network congestion. The PIR is higher than the CIR to allow for bursts (spikes in bandwidth usage).



PKI (Public-Key Infrastructure) is the framework of servers, software, procedures and policies that handles (public-key cryptography) keys.



Public-Key Infrastructure (X.509) refers to an IETF working group and the protocols and architecture that it has drafted based on X.509.



PKM-EAP (Privacy Key Management - Extensible Authentication Protocol) is an authentication and key exchange mechanism used in IEEE 802.16.



Privacy Key Management version 2 (PKMv2) is a security protocol designed to handle the distribution of keys during the process of authenticating a user and setting up a secure connection to the network.


PKMv2 and WiMAX

WiMAX uses the PKMv2 (Privacy Key Management version 2) security standard for authentication. PKMv2 employs a variety of keys to provide end-to-end data security.



Plaintext is another term for unencrypted data, is clear text, readable by anyone. See also Encryption, Decryption, Cipher, Ciphertext.



Power Line Communication (PLC), also called Broadband over Power Lines (BPL) or Power Line Telecoms (PLT), technology uses the current electricity networks (power lines) for data and voice transmission by superimposing an analog signal over the standard 50 or 60 Hz alternating current (AC). It supports data rates of up to 85 Mbps.



Plenum spaces are those areas in a building used for infrastructure rather than habitation. Materials that are "plenum rated" for use in these spaces (such as plastic cabling and equipment housing) burn at higher temperatures and emit less toxic fumes than their non-plenum-rated counterparts; in the event of a building fire the danger of asphyxiation is greatly reduced.



See PLC.



In WPA or WPA2, a Pairwise Master Key (PMK) is derived through a successful authentication between a wireless client and AP and used to generate unique data encryption keys.


PMK caching

In WPA2, PMK caching allows an AP and wireless client to store and use the PMK and information about their previous authentication, so that the AP can quickly re-authenticate the wireless client. See also PMK.



Power ManageMent (PMM) is an ADSL2 feature that manages transmission power based on line conditions.



PMS is an automated billing system commonly used by hotels to perform in-room billing of services.



A PNS is the box that hosts both the PPP and the PPTP stacks and forms one end of the PPTP tunnel. Must have IP connectivity.



Podcasting is a way of distributing files on the Internet using web feeds.


PoE (Power over Ethernet)

A technology enabling an Ethernet network cable to deliver both: data and power. PoE is the ability to provide power to a PoE-enabled device via an 8-pin CAT 5 Ethernet cable, eliminating the need for a nearby power source.



A network connection between two nodes (host computers).



A network configuration in which one node (host computer) is capable of communicating with numerous other nodes.


Point-to-Point Protocol over Ethernet

Point-to-Point Protocol over Ethernet (PPPoE) mimics an Internet dial-up connection over an Ethernet cable.



A policy defines the action(s) to be performed on a traffic flow that has been classified. See also Bandwidth Management, Classifier, Firewall and VPN.


Policy Severity

Intrusions are assigned a severity level from very low to severe. The intrusion severity level determines the default signature action applied.



A PON (Passive Optical Network) uses optical fiber cables to the curb (FTTC), building (FTTB) or home (FTTH). "Passive" means that no power is required on an intermediary device on the network as the signals are going through the cables. See also ONU and OLT.



This is a common protocol used for sending, receiving, and delivering mail messages. It uses TCP port 110 by default.



POP3 over TLS/SSL (POP3S) allows users to use TLS/SSL to create a secure POP3 connection for receiving e-mail. POP3S uses TCP or UDP port 995 by default. See POP, TLS, and SSL.



An Internet port refers to a number that is part of a URL, appearing after a colon (:), directly following the domain name. Every service on an Internet server listens on a particular port number on that server. Most services have standard port numbers, for example, Web servers normally listen on port 80.


Port (H/W)

An interface on a computer for connecting peripherals or devices to the computer. A printer port, for example, is an interface that is designed to have a printer connected to it. Ports can be defined by specific hardware (such as a keyboard port) or through software.


Port Authentication

Port authentication allows a networking device to authenticate users against a RADIUS server for network security. The networking device checks the indentity of a user before access to the network behind it is allowed.

Port Bonding

This is the aggregation of separate physical DSL port links into one logical link; for example, three SHDSL links of 2.3 Mbps can be aggregated into one logical 6.9 Mbps link.


Port Forwarding

Use this feature to forward incoming service requests to a server on your local network. You may enter a single port number or a range of port numbers to be forwarded, and the local IP address of the desired server.


Port Isolation

On an IP DSLAM, the port isolation feature increases security by allowing each subscriber port to communicate with the uplink port but not communicate directly with the other subscriber ports.


Port Mirroring

Port mirroring allows you to copy traffic from one port to another port in order to examine the first port's traffic without interfering with it.


Port Restricted Cone NAT

Restricted cone NAT maps all requests from the same private IP address and port to the same public source IP address and port. A host on the Internet can only send a packet to the private IP address and port if the private IP address and port has previously sent a packet to that hosts IP address and port.


Port Security

Port security allows only packets with dynamically learned MAC addresses and/or configured static MAC addresses to pass through a port on the switch.


Port Triggering

See "Trigger Port Forwarding".


Port Trunking

This is the aggregation of separate physical port links into one logical link; for example, two fast Ethernet links can be aggregated into one logical 200Mbps link.


Port-based Q-in-Q

Port-based Q-in-Q lets a switch treat all frames received on the same port as the same VLAN flows and add the same outer VLAN tag to them, even they have different customer VLAN IDs.


Port-based VLAN

Port-based VLANs are VLANs where the packet forwarding decision is based on the destination MAC address and its associated port. Port-based VLANs are specific only to the device on which they were created.


Portal Page

A portal page is the first web site to which a subscriber is directed after logging in successfully.



The analog telephone service that runs over copper twisted-pair wires and is based on the original Bell telephone system. Twisted-pair wires connect homes and businesses to a neighborhood central office. This is called the local loop. The central office is connected to other central offices and long-distance facilities.


Powered Device (PD)

A powered device (PD) is a device that supports PoE (Power over Ethernet) so that it can receive power from another device through an Ethernet connection.



Powerline technology enables devices connected on the same electrical circuit through standard power outlets to connect with each other on a network. Powerline networks on coaxial cable are also possible.


Power Management

Power Management helps to reduce power consumption by allowing a device to go into sleep mode when no network activity is detected for a certain period of time on the device.


Power Injector

A power injector is a device that provides power to a PoE (Power over Ethernet)-enabled device via an (8-pin) CAT 5 Ethernet cable, eliminating the need for a nearby power source. See also Power over Ethernet.



PPP encapsulates and transmits IP (Internet Protocol) datagrams over serial point-to-point links. The protocol is defined in IETF (Internet Engineering Task Force) RFC 1661 through 1663. PPP provides router-to-router, host-to-router, and host-to-host connections.



One of the two types of PPP interfaces you can define for a Virtual Circuit(VC), the other being PPPoE. You can only define one PPPoA per VC.


PPPoE (Point to Point Protocol over Ethernet)

PPPoE relies on two widely accepted standards: PPP and Ethernet. PPPoE is a specification for connecting the users on an Ethernet to the Internet through a common broadband medium, such as a single DSL line, wireless device or cable modem. Also: a type of broadband connection that provides authentication (username and password) in addition to data transport.


PPPoE Intermediate Agent

The DSLAM PPPoE Intermediate Agent feature adds a vendor-specific tag to PADI (PPPoE Active Discovery Initialization) and PADR (PPPoE Active Discovery Request) packets from PPPoE clients. This tag is defined in RFC 2516.


PPPoE Intermediate Agent Information

Similar to DHCP relay option82, some DSLAMs can insert line information into client PPPoE Discover Initialization (PODI) packets. This allows a PPPoE termination server to identify and authenticate a PPPoE client.



Point-to-Point Tunneling Protocol (PPTP) is a network protocol that enables secure transfer of data from a remote client to a private server, creating a Virtual Private Network (VPN) using a TCP/IP-based network.



PPVCs (Priority-based PVCs) allow you to give different priorities (and IEEE 802.1p priority tags) to PVCs that are members of the same VLAN.



The preamble is a seven-byte field at the start of an Ethernet frame header that helps synchronize transmissions between the sender and receiver.


Preamble and WiMAX

A preamble is an index identifier in the header of a base station's broadcast messages. In the beginning of a mobile station (MS) network entry process, the MS searches the preamble and uses it to get further channel characteristics information. It is used to synchronize the upstream and downstream transmission timing with the base station.



Preemption allows a router to improve traffic management by allowing the high-priority packets to preempt the low-priority packets.


Prefix list

An IPv6 address prefix is similar to an IPv4 subnet mask, and is used to represent the network address. The prefix list allows an IPv6 device to determine whether an IP address is on the same network as the device or should be reached through a router.


Pre-Shared Key

A pre-shared key is a password shared between the server and the client that unlocks the algorithm used to encrypt the data traffic between them. Without the proper password, the client and the server cannot communicate.


Primary Rate Interface

Primary Rate Interface Primary Rate Interface (PRI) is an Integrated Services Digital Network (ISDN) physical layer standard used to transmit voice and user data. ISDN PRI is used in larger enterprises and provides data rates more than 1.5Mbps.


Print Server

A print server is a device or software that provides users on a network with shared access to one or more printers. The print server acts as a buffer, holding the information to be printed out until the printer becomes free.


Product Serial Number

This is a unique multi-digit number found on the product label that identifies the product. You need this number to register your product.


Progressive scan

Using progressive scan, images are captured, transmitted, and shown line by line starting from the top and going to the bottom. Progressive scan has better picture quality than interlaced scan but requires twice the bandwidth.


Promiscuous Packet Capture

Actively capturing packet information from a network. Most computers only collect packets specifically addressed to them. Promiscuous packet capture acquires all network traffic it can regardless of where the packets are addressed.



A “language” for communication on an network. Protocols are sets of standards or rules used to define, format and transmit data across a network. There are many different protocols used on networks. For example, most web pages are transmitted using the HTTP protocol. Low-level protocols define the electrical and physical standard, while high-level protocols deal with formatting of data.


Protocol Anomaly Detection

Protocol Anomaly Detection is an intrusion detection method that checks for RFC protocol



Protocol Based VLAN

In a switch, protocol based VLANs allow you to group untagged upstream traffic into logical VLANs based on the protocol (Ethernet type). One advantage of using protocol based VLANs is that priority can be assigned to traffic of the same Ethernet type.


Protocol Decode

Protocol decode also known as Protocol Anomaly Detection or Protocol Validation performs a full protocol analysis, decoding and processing the packet in order to highlight anomalies in packet contents. This is quicker than doing a search of a signature database. It is more flexible in capturing attacks that would be very difficult to catch using pattern-matching techniques, as well as new variations of old attacks, which would require a new signature in the database.


Protocol Filters

Use Protocol Filters to decide whether or not to allow passage of a data packet and/or to make a call. Protocol filters act on IP/IPX packets and can serve as a limited firewall.


Proxy Server

A proxy server is a server between a client application, such as a web browser, and a real server. It intercepts all requests to the real server, fulfills those it can and forwards the rest to the real server.



PSD (Power Spectral Density) defines the distribution of a DSL line's power in the frequency domain.


PSD profile

A PSD profile specifies the maximum allowable downstream and upstream transmission power of each DSL frequency band.



The Phase-Shift Keying (PSK) digital modulation technique shifts the phase (period) of the carrier wave.



Public Switched Telephone Network was put into place many years ago as a voice telephone call-switching system. The system transmits voice calls as analog signals across copper twisted cables from homes and businesses to neighborhood COs (central offices); this is often called the local loop. The PSTN is a circuit-switched system, meaning that an end-to-end private circuit is established between caller and the person called.


PSTN Lifeline

The Public Switched Telephone Network lifeline feature lets you have VoIP phone service and analog phone service at the same time. You can receive incoming analog phone calls even while someone else is making VoIP phone calls. You can still make analog phone calls if the device loses power.


PTR Record

A PTR (pointer) record is also called a reverse record or a reverse lookup record. It is a mapping of an IP address to a domain name.



PTT is a generic European name that usually refers to state-owned telephone companies.

Public Key Encryption System of encrypting electronic files using a key pair. The key pair contains a public key used during encryption, and a corresponding private key used during decryption.


Public Key Certificate

Public key certificates are used by certain programs (such as web browsers and personal encryption programs) to ensure that a secure web site is legitimate. When a certificate authority (such as VeriSign, Comodo, or Network Solutions) receives a certificate request from a website operator, it confirms the web domain and contact information in the request match those on public record with a domain name registrar. If the information matches, then a public key certificate is issued to the website operator to place on a website.



In mobile telephony, a Personal Unblocking Key (PUK) is a numeric password used to unblock a SIM card. A SIM card can become blocked if it has password protection activated (via the SIM PIN feature) and an incorrect PIN has been entered three times. The PUK is available from the cellular service provider who supplied the SIM card. If an incorrect PUK is entered ten times in a row, the SIM card can become permanently unusable. PUK is also known as PUC (PIN Unblocking Code).


Pulse Dialing

Pulse dialing call setup signaling sends a series of clicks to the local phone office in order to dial numbers.



A PVC is a logical point-to-point circuit between customer sites. PVCs are low-delay circuits because routing decisions do not need to be made along the way. Permanent means that the circuit is preprogrammed by the carrier as a path through the network. It does not need to be set up or torn down for each session.



This is the Port VLAN ID (PVID) a device assigns to untagged frames received on a port.



Protocol VLAN (PVLAN) adds a VLAN ID and IEEE 802.1p priority to a specific protocols untagged traffic. This group traffic of the same protocol into one VLAN.