Glossaries

• Port Forwarding NAT (Destination NAT)
• Port Forwarding NAT is a technique that allows external devices to access specific services hosted on devices within a private network. It involves configuring a router or firewall to forward incoming traffic on a specific external port to the internal IP address of the device hosting the service, enabling external access without exposing the entire internal network.
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• Pulse Amplitude Modulation (PAM)
• A form of signal modulation where the pulse stream samples an incoming data stream at fixed points, sending only the amplitude. The amplitude can be analog (one of many numbers) or digital (one number out of a fixed collection).
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• Packet-Switching Network
• The New Generation “Packet Transport Network” combines the advantage of the SDH with the high capacity transport of the packet technology. This technology takes the packet switching network as the core of transport. PTN uses either Carrier Ethernet or MPLS as the transport encapsulation running over GE/10GE. Together with Ethernet Synchronous (SyncE) fibers and PTP 1588v2 timing technologies, PTN provides a high capability of statistical multiplexing for carrying the TDM (SDH/PDH), ATM, and Ethernet services in PWE3. PTN insures the Operation Administration Maintenance (OAM) with synchronization and the full end-to-end circuit protection.
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• Private Branch Exchange (PBX)
• Private telephone network that serves a certain company or office. Can be connected to the wider publicly switched telephone network (PSTN).
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• Pseudowire Emulation Edge to Edge (PWE3) or Pseudowire (PW)
• The PseudoWire Emulation End-to-End is used to transport a service such as TDM (E1/T1/E3/DS3), SDH, ATM, Ethernet with VLAN, Q-in-Q, SAN…over Packet Switched Network (PSN): IP, Ethernet or MPLS. Different emulations are used like SAToP for unframed E1/T1/E3/T3, CESoPSN for framed TDM DS0 and CEP for channelized SDH/SONET at the VCx/VTx level.
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• Plesiochronous Digital Hierarchy (PDH)
• The Plesiochronous Digital Hierarchy is the old technology of communication between TDM nodes with similar clock. Now the TDM nodes are synchronized with the same clock and do not need the hierarchy. But the PDH name is often used to talk about TDM DS0 circuits and equipment.
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• Private Line, Automatic Ringdown Plug-in Card (PLAR card)
• An Electronic Order Wire (EOW) device. It allows two dual private line automatic ringdown interfaces to be multiplexed to 64 kbps DSO signals. PLAR refers to a private telephone line that is not serviced by a carrier. When one handset is taken off the hook, it applies a voltage across the line that causes the other end to ring.
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• Payload Loopback (PLB)
• Loopback of the "payload" portion of the signal, used for testing.
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• Power over Ethernet (PoE)
• Power over Ethernet (PoE), as described in the IEEE 802.3af protocol, is a technology that allows power to be carried over existing Ethernet cables, especially Cat-5e cables. The power to run the device and the user data can be carried over the same physical wire. Thus with PoE, the number of wires can be kept to a minimum. In addition, when operating with a UPS (Uninterruptable Power Supply), PoE ensures devices still function during a power failure.
  
  Two major components of the PoE system are the Power Sourcing Equipment (PSE) and the Powered Device (PD). A PSE is a device that supplies power on the Ethernet cable while a PD accepts power from a PSE. When a PSE device is a switch or similar device, it is called an endspan. When a PSE device is intermediate between non-PoE and PoE devices, then it is called a midspan.
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• Parts Per Million (PPM)
• Equivalent to 1 part out of 1,000,000 units. A engineering measure used to identify small quantities. Dimension-less.
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• Point to Point Protocol (PPP)
• A data link protocol that is used to establish a direct connection between two networking nodes. Works over synchronous and asynchronous circuits. It has superseded SLIP (serial line internet protocol), an earlier protocol. It works with many other higher level protocols such as IP and AppleTalk.
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• Precision Time Protocol (PTP)
• The Precision Time Protocol (PTP), as defined in the IEEE1588-2008 standard, is a protocol used to synchronize clocks throughout a computer network. In a local area network, it achieves clock accuracy to the sub-microseconds, making it suitable for fine measurement and control systems.
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• Pseudo Random Binary Sequence (PRBS)
• A sequence of N bits that appears to be random but is the result of a fixed deterministic process. N can be chosen to be a sufficiently large number.
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• Parallel Redundancy Protocol (PRP)
• PRP is a network protocol standard for Ethernet that provides seamless failover against failure of any network component.
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• Public Switched Telephone Network (PSTN)
• Also called POTS or plain old telephone system, it refers to the variety of telephone services and systems throughout the world. It is a circuit switched, not a packet switched, network. Traditionally mechanical/analog, the system is now entirely digital except for devices at the customer's premises.
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