Ethernet: a system for connecting computer systems, with protocols to control the passing of information and to avoid simultaneous transmission by two or more systems.

Active Ethernet (AE): An Active Ethernet network provides each subscriber with their own fiber link to the network node switch, which links the local network to the Internet. In comparison, a GPON network uses passive optical splitters to connect up to 32 subscribers to a single fiber link to the network node. AE makes higher bandwidth possible by the direct link from the switch to the subscriber.

Fiber-Optic: Optical fiber is a strand of glass about as thin as a human hair that transmits light pulses carrying digital information. The light pulses are generated, received, and converted from / to electrical signals by electronic equipment at each end of the fiber, to form a communications network. Fibers are grouped in bundles in cables throughout the network. Optical fiber is less expensive and lighter weight than copper wires and can transmit more data with less power and signal degradation over longer distances. Optical fiber is electrically non-conductive and not subject to electromagnetic interference.

FTTx (Fiber-to-the-x): Fiber to the x (FTTX) is a generic term for any broadband network architecture using optical fiber to provide all or part of a last mile telecommunications system. Fiber-to-the-home (FTTH) refers to fiber optic cable connections to individual residences; also known as Fiber-to-the-premise (FTTP). Fiber-to-the-curb (FTTC) refers to fiber optic cable extended along a street or road, passing individual premises.

Gigabit (Gb): A Gigabit of Internet bandwidth is 1,000 Megabits (Mb). A Gigabit network can provide data transfer rates of one gigabit per second (Gbps) over fiber. Most end-user devices process data at slower speeds than fiber.

Gigabit as a measure of bandwidth is not to be confused with Gigabit as a measure of data. Bandwidth (what engineers call bitrate) refers to data transfer rates: how fast information can move between devices. A Gigabit of data, in contrast, is a measurement of quantity: one billion bits of data.  It takes eight bits (referred to as a byte) to store a single character of text.

ISP (Internet Services Provider): an entity that provides Internet service over the network.

“Middle Mile”: the network that is owned by the Massachusetts Broadband Institute which provides connectivity from local “last mile” networks to the Internet.

NO (Network Operator): an entity that monitors the performance of the network and takes corrective action in the event the network is not functioning properly.

ONT (Optical Network Terminal): a network interface device used with fiber-optic systems. The ONT is the demarcation point between the fiber-optic network and the subscriber premises Ethernet wiring to the subscriber router, which serves the subscriber’s devices.  The ONT converts optical signals into electrical signals, and vice-versa. The ONT terminates the fiber optic line in an inner compartment and the premises Ethernet and telephone wiring in an outer compartment. The ONT is powered from the subscriber premises electrical system, through an uninterruptible power supply (UPS) unit.

Point of Presence: A Point of Presence is a demarcation and access point to the Internet. It is a physical location that houses electronic equipment necessary to connect the “last mile” network to the “middle mile,” which connects through the ISP to the Internet.

Symmetrical Bandwidth: equal upload and download capacity. Download (or downstream) bandwidth is the path that brings information from the network to a subscriber’s device. Upload (or upstream) is the path that carries information from the subscriber’s device into the network. All Internet activity involves both paths. Video streaming is an example of an activity that uses more downstream than up. Cloud services, telehealth, and video conferencing are examples of activity that use up and down streams more evenly and may use upstream more than down.

UPS (Uninterruptible Power Supply): an electrical apparatus that converts AC (alternating current) from the electrical grid into DC (direct current) to the ONT. The apparatus provides surge protection and filtering to correct some common utility grid problems—voltage and frequency instabilities—and contains a battery backup to provide short-term power to the ONT in the event of a grid power outage. The UPS is connected to the ONT with two power wires and five signal wires. The battery in the UPS unit is a sealed, maintenance-free lead-acid type. 

Net Neutrality: the principle that Internet service providers should enable access to all content and applications regardless of the source, and without favoring or blocking particular products or websites.