RAD - P

Packet - An ordered group of data and control signals transmitted through a network, as a subset of a larger message.

Packet Switching - A data transmission technique, which divides user information into discrete data envelopes called packets, and sends the information packet by packet.

PCM (Pulse Code Modulation) - A procedure for adapting an analog signal (such as voice) into a 64 kbps digital bit stream for transmission.

PON (Passive Optical Network) - A high bandwidth, point-to-multipoint optical fiber network based on ATM, Ethernet or TDM. In this type of optical network, wavelengths of light are divided into timeslots so that each wavelength can be shared by a number of users. With PONs, a single fiber from the carrier’s exchange can service 16, 32 or more buildings through the use of both passive devices to split the optical signal, and PON protocols to control the sending and transmission of signals across the shared access facility.

Pseudowire - Point-to-point connections set up between pairs of Provider Edge routers. Their primary function is to emulate (typically layer 2) native services like ATM, Frame Relay, Ethernet, low-rate TDM, or SONET/SDH over an underlying common packet switched network (MPLS, IP, or L2TPv3) network core. To achieve this, each of these technologies is encapsulated into a common MPLS format. Pseudowires are defined by the IETF PWE3 (Pseudowire Edge to Edge Emulation) WG.

QoS (Quality of Service) - Refers to the capability of a network to provide better service to selected network traffic over various technologies, including Frame Relay, Asynchronous Transfer Mode (ATM), Ethernet and 802.1 networks.

SDH (Synchronous Data Hierarchy) - The European standard for using optical media as the physical transport for high speed long-haul networks.

SHDSL - A standardized method (ITU-T G.991.2, Single-pair High-speed Digital Subscriber Line) to transport data symmetrically at rates of 192 kbps to 2.3 Mbps over 2-wire, or 384 kbps to 4.6 Mbps over 4-wire. Also known as Symmetric High-Bitrate Digital Subscriber Loop by the DSL Forum.

Silence Suppression - In a telephone conversation, only about 50% of the full duplex connection is used at any given time. This is generally because only one person talks while the other person listens. In addition, voice packets are not sent during interword pauses and natural pauses in the conversation, reducing the required bandwidth by another 10%. Silence suppression frees this 60% of bandwidth on the full duplex link for other voice or data transmissions.

SLA (Service Level Agreement) - A formal negotiated agreement between customers and their service provider, or between service providers. It records the common understanding about services, priorities, responsibilities, guarantees, etc. with the main purpose to agree on the level of service. For example, it may specify the levels of availability, serviceability, performance, operation, or other attributes of the service like billing and even penalties in the case of violation of the SLA.

SONET (Synchronous Optical Network) - A North American standard for using optical media as the physical transport for high-speed long-haul networks. SONET basic speeds start at 51.84 Mbps and go up to 2.5 Gbps.

Statistical Multiplexer (STM or STDM) - A device connecting multiple channels to a single link by dynamically allocating timeslots to the channels based on their transmission activity.

Synchronous Transmission - Transmission in which data bits are sent at a fixed rate, with the transmitter and receiver synchronized.