Glossary of Terms
The below product glossary consists of definitions of standard industry terms as well as IMC Networks-specific terms, to help clarify the function and performance of IMC's product line.
INDEX: 10 Gigabit Ethernet | 10/100 | 10/100-SSFX | 1000Base-LX | 1000Base-SX | 100Base-FX | 100Base-TX | 10Base-2 | 10Base-F | 10Base-T | 802.1p | 802.1Q | 802.3 | 802.3af | 802.3ah | Access Point | AIS | ANSI | Attenuation | Autocross | Autonegotiation | BERT | BNC/FX | BNC/SSFX | Bridge | Bridged Network | Bridging | Broadcast Storm | Carrier Ethernet | CAT-5 | CO | CPE | CSU | CWDM | dB | dBm | DCE | DHCP | Digital Diagnostics Monitoring Interface (DDMI) | Digital Loopback | DIP | DS1 Channel | DS3 Channel | DTE | E1 | E3 | Ethernet | Ethernet Private Line (EPL) | EtherType | Fast Ethernet | FiberAlert | Firmware | FO | FTTx | Full Duplex | FX | Gigabit | Gigabit Ethernet | GUI | Half Duplex | IE | IEEE | iMcV | ISA | ITU | J1 | Kbps or KB/s | Last Gasp | Legacy Equipment | LinkLoss | LX | M2MM | Mbps or MB/s | MEF | MIB | MSA Compliant | MTU | Multimode | Network Layer | NIC | NID (Network Interface Device) | OAM | OC | OC-12c | OC-3c | OC-48c | OSI | OSI Model | PCI | Physical Layer | PoE | PoE+/PoE Plus | Protocol | Pulsing FiberAlert | Q-in-Q | QoS | Repeater | RFC | RFC-1643 | RJ-45 | RJ-48 | RMON | RMON 2 | ROHS | RX | S2MM | S2SM | SDH | SFP | SFP/1250 | SFP/1250-ED | SFP/155 | SFP/155-ED | SFP/2.4 | SFP/2.4-ED | SFP/SFP | Singlemode | SNMP | SONET | SSFX | SSLX | STP | SX | T1 | T3 | TDM | Telco | Telnet | TFTP | TP | TP-TX/FX | TP-TX/FX-CWDM | TP-TX/SSFX | TP-TX/SX | TP/BNC | TP/Fiber | TP/FO | TP/SSFiber | Transceiver | TX | TX Rate | TX+FX-CWDM | TX/3 | TX/3+FX | TX/3+SSFX | TX/3+SX | TX/4 | TX/4+SFP | TX/5 | TX/FX | TX/LX | TX/SFP | TX/SSFX | TX/SSLX | TX/SX | TX/TX | UMA | USB | UTP | VDSL | VLAN | VLAN Tagging | VoIP | WAN | WDM |
10GE, 10GbE, 10 GigE. A standard of Ethernet with a nominal data rate of 10 Gbps (billion bits per second), ten times faster than gigabit Ethernet.
IMC term used to describe a dual rate media converter that converts from 10Mbps to 10Mbps (10BASE-T to 10BASE-FL), or 100Mbps to 100Mbps (100BASE-TX to 100BASE-FX). Devices described as 10/100 are not rate converters (see TP-TX/FX). Not to be confused with 10/100 switches, which adjust their rates automatically.
IMC term for single strand versions of 10/100 products (see 10/100)
A Gigabit Ethernet standard for fiber at 1300 nm or 1550 nm wavelength.
A Gigabit Ethernet standard for fiber at 850 nm wavelength.
100 Mbps Ethernet operating on multimode fiber optic cable
100 Mbps Ethernet operating on two-pair Category 5 UTP or STP.
10Base2, an approved standard, is the implementation of the IEEE 802.3 Ethernet standard designed to operate over thin net coaxial cable wire at 10 Mbps. The 10Base2 standard limits segments to 185 meters.
10BaseF is a standard for IEEE 802.3 Ethernet designed to operate over fiber optic cable. Also called 10BaseFL.
10BaseT, is a standard for IEEE 802.3 Ethernet standard designed to operate over unshielded twisted-pair (UTP) wire at 10 Mbps. The 10BaseT standard limits UTP segments to 100 meters. UTP is standard telephone wire.
802.1p is a standard that provides a mechanism for providing Quality of Service (QoS) at the MAC layer. A priority field is added to the Ethernet frame.
VLAN tagging
An Ethernet specification defined by the Institute of Electrical and Electronics Engineers (IEEE). The 802.3 specification covers rules for configuring Ethernet LANs, the types of media that can be used and how the elements of the network should interact.
The formal IEEE specification for Power over Ethernet. (see PoE)
IEEE 802.3ah is a collection of protocols specified in IEEE 802.3, defining the Ethernet in the access networks, i.e. first or last mile. Also known as Ethernet in the First Mile (EFM).
A device that allows wireless-equipped computers and other devices to communicate with a wired network.
Alarm Indication Signal. One of the OAM function types used for fault management. Alarm indication signal (AIS) is a signal transmitted by a telecommunications system to let the receiver know that some remote part of the end-to-end link has failed, even if the system it is directly connected to is still working. Other systems attached to a system transmitting AIS then relay the AIS indication onwards to other systems.
American National Standards Institute. The USA’s member body to the International Standards Organization. ANSI is a non profit independent body that is supported by trade organizations, professional societies and industry.
Signal power loss through equipment, lines or other transmission devices. Measured in decibels.
Autocross allows for automatic detection of the correct MDI / MDI-X configuration on the copper ports (RJ-45), eliminating the need to specify different cables (crossover or straight-through) and thus eliminating another step in troubleshooting.
Auto-negotiation allows devices to automatically assign the most efficient line speed (10/100/1000 Mbps) and mode (Full-Duplex or Half-Duplex) for a particular network segment between two devices.
Bit Error Rate Test/Tester. A device used to test the bit error rate of a communications circuit (i.e. the ratio of received erroneous bits to received bits, usually a number referenced to a power of 10).
IMC term used to describe IMC's DS3/E3 (BNC connector) to fiber extenders.
Single strand version of IMC's DS3/E3 converters
A device that connects two different kinds of local networks, such as a wireless network to a wired Ethernet network.
A network in which all devices are in the same broadcast domain.
Interconnecting local area networks at the OSI Data Link Layer, filtering and forwarding frames according to media access control (MAC) addresses.
A Broadcast storm is the accumulation of broadcast and multicast traffic on a computer network. A broadcast storm can consume sufficient network resources so as to render the network unable to transport normal traffic.
A standardized, carrier-class Service and Network defined by five attributes that distinguish Carrier Ethernet from typical LAN based Ethernet.
Category 5 UTP. Unshielded Twisted Pair standard, commonly used with ATM interfaces for higher-speed cell transmission (more than 50 Mbps).
Central Office. Telephone company switching office. This is where you would find the local telco switch that connects to your telephone.
Customer Premise Equipment. Equipment that is located on the customer's premises (physical location) rather than on the provider's premises or in between.
Channel Service Unit. A digital-interface device used to connect a router to a digital circuit such as a T1 or T3 line.
A method of combining different wavelengths of light traveling over a fiber optic cable, in order to increase the carrying capacity of the fiber.
Decibel. The standard unit of measure used to express the relative strength of a signal (the gain or loss of optical power).
A measure of power in communications: the decibel in reference to one milliwatt (0 dBm = 1 milliwatt and -30 dBm = .001 milliwatt).
Data Communications Equipment. Or data circuit-terminating equipment. Devices and connections of a network that make up the network end of the interface between the network and the user. A modem is an example of a DCE.
Dynamic Host Configuration Protocol. A protocol that allows TCP/IP settings of a networked computer, called a DHCP client, to be configured automatically from a central DHCP server.
Digital Diagnostics Monitoring Interface (DDMI)
Industry standard feature that allows the user to monitor real-time parameters of an SFP, such as optical output/input power, temperature, laser bias current, and transceiver supply voltage.
A technique for testing the digital processing of a communications device. The loopback is toward the line side of a modem, but tests most of the circuitry in the modem under test.
Dual In-Line Package. A switch typically found on a printed circuit boards, and used to change the electrical performance of a device. Also known as DIP switch.
Digital Signal Level 1. Framing specification used in transmitting digital signals at 1.544 Mbps on a T1 facility or 2.048 Mbps on an E1 facility.
A 44.736 Mbps line consisting of seven DS2 channels. A DS3 line is also called a T3 line.
Data Terminal Equipment. As defined in the RS-232 specification, equipment to which DCE (Data Communications Equipment) is connected, such as personal computers, data terminals or printers. DTE refers to application equipment, such as a videoconference terminal or LAN bridge or router, while DCE refers to equipment such as network access equipment.
A 2.048 Mbps line, common in Europe, that supports thirty-two 64 kbps channels, each of which can transmit and receive data or digitized voice. The line uses framing and signaling to achieve synchronous and reliable transmission. The most common configurations for E1 lines are E1 PRI, and unchannelized E1.
The European standard for high speed digital transmission, operating at 34 Mbps.
A widely used standard of computer networking technologies used for local area networks (LANs) with data rates of up to 10 Mbps.
a data service defined by the MEF, providing a point-to-point Ethernet Virtual Connection (EVC) between a pair of dedicated User–network interfaces (UNIs), with a high degree of transparency.
EtherType is a field in the Ethernet networking standard used to indicate which protocol is being transported in an Ethernet frame.
A standard of Ethernet with a nominal data rate of up to 100 Mbps.
FiberAlert is a troubleshooting feature available in select IMC products, designed to minimize the problems associated with the loss of one strand of fiber. If a strand is unavailable, the device at the receiver end notes the loss of link. The device will then stop transmitting on the fiber until a signal or link is received. The result is that the link LED on BOTH sides of the fiber connection will go out indicating a fault somewhere in the fiber loop.
The programming code that runs a networking device.
Fiber Optic - used by IMC to refer to a 10Base-F 10Mbps signal
Fiber to the x. A generic term that refers to any number of configurations of fiber deployment based on the location of the fiber’s termination point (e.g., fiber to the curb, fiber to the desk, etc.).
The ability for communications to flow both ways (transmit and receive) over a communications link simultaneously.
Derived from the IEEE standard 100Base-FX, FX is how IMC refers to a 100Mbps signal running over fiber
One billion bits.
A standard of Ethernet with a nominal data rate of up to 1000 Mbps.
Graphical User Interface, such as IMC's iView element management system
Alternating transmissions in which each station can either transmit or receive, but not both simultaneously.
IE stands for “Industrial Equipment”, IMC Networks’ designation for products that have been designed to operate in a wider temperature range rather than the typical 0°C to +40°C. IMC Networks’ “IE” products contain additional features designed for industrial applications, such as multiple powering options and DIN clips.
Institute of Electrical and Electronics Engineers. An American organization which is active in formulating LAN standards. It has established many technical committees with designations prefixed by IEEE 802. The IEEE is a member of ANSI and ISO.
iMcV is an IMC term which indicates that the product is a module designed for installation in a managed iMediaChassis or and unmanaged MediaChassis.
Industry Standard Architecture - an older standard for attaching a peripheral device to a motherboard. The newer standard is PCI. (see PCI)
International Telecommunication Union. A European-based, international advisory committee recommending worldwide standards for transmission.
A digital transmission link with a capacity of 1.544 Mbps used in Japan. (see T1)
Kilobytes per second (or thousands of bits per second). A measure of bandwidth on a data transmission medium.
Available in select IMC products, the Last Gasp feature is Trap notification triggered (usually via a SNMP application) when the AC line fails, when power supplies are powered down or in the possibility of a power supply failure
Older network equipment that continues to be used, typically because it still functions for the users' needs, even though newer, faster technology is currently available.
LinkLoss is a troubleshooting feature that works on either the twisted pair port (TP/TX) or the fiber port (FO/FX) of devices which have at least one of each port type. When a fault occurs on one segment of a conversion, LinkLoss detects the fault and passes this information to the other segment. For example, if a media converter is not receiving a fiber link, FO/FX LinkLoss disables the transmitter on the media converter’s twisted pair port. This results in a loss of link on the remote twisted pair device.
Derived from the IEEE standard 1000Base-LX, LX refers to a 1000Mbps signal running over fiber. Typically longer range than SX fiber (1000BASE-SX)
IMC term used to signify a protocol independent mode converter converting from multi-mode to multi-mode fiber. Typically 850nm to 1300nm.
Megabytes per second. One million bits per second; a unit of measurement for data transmission.
Metro Ethernet Forum. A non-profit organization chartered with the mission of accelerating the adoption of optical Ethernet as the technology of choice in future metro networks worldwide. Ethernet was chosen for its relative simplicity and popularity with end-users, as well as for lowering costs of Ethernet equipment.
Metro Ethernet Forum. A nonprofit international industry consortium, dedicated to worldwide adoption of Carrier Ethernet networks and services.
Management Information Base. A directory listing the logical names of all information resources residing in a network and pertinent to the network’s management. A key element of SNMP management systems.
Multi-source Agreement. Universal compatibility specification provided to systems manufacturers, system integrators, and suppliers, so that they can build both SFP transceivers and network hardware so that they will interoperate with each other.
Maximum transmission unit. A networking term that refers to the size (in bytes ) of the largest packet or frame that a given layer of a communications protocol can pass onwards.
Fiber optic cabling used when propagating several modes at the same time is necessary (singlemode allows only one mode to propagate at a time). Multimode fiber has a large core diameter: 50-200 microns compared with the wavelength of light. It therefore propagates more than one mode. With multimode fiber, light traverses multiple paths, some longer than others. This leads to dispersion, which reduces optical range at high bit rates.
The third layer in the OSI model, it is the logical network entity that services the transport layer. The network layer is responsible for ensuring that data passed to it from the transport layer is routed and delivered through the network.
Network Interface Card. An adapter card inserted into a computer to provide network communication capabilities. It connects the server to the network. It is also referred to as an Ethernet adapter.
NID (Network Interface Device)
A device that functions as the interface or demarcation point between the Telco’s equipment and the customer’s equipment. Sometimes referred to as a Network Interface Unit (NIU).
Operation Administration and Maintenance. A set of network management functions that provide for network fault and performance management, analysis and fault isolation. OAM functions exist in carrierclass TDM and ATM networks, but are now also being implemented in MPLS and Ethernet networks. These capabilities will provide the basic tools for carriers to monitor, diagnose, and troubleshoot first-mile Ethernet access links.
Optical Carrier. A hierarchy of optical signals used to classify speeds or capacities of fiber lines, especially as related to the SONET standard. The basic speed is OC-1 (52 Mbps). An OC-3 fiber line has a capacity of 155 Mbps.
A transmission rate of 622 Mbps.
A transmission rate of 155 Mbps.
A transmission rate of 2.5 Gbps.
Open Systems Interface. The ISO/OSI model is designed to allow for inter-connectivity between vendors. The OSI model is a seven-layer network architecture being used for the definition of network protocol standards to enable any OSI-compliant device to communicate with any other OSI-compliant device for a meaningful exchange of information. The OSI layers refer to each specific function: Physical, Data Link, Network, Transport, Session, Presentation and Application.
A standard reference model for communication between two end users in a network. The OSI Reference Model describes seven layers of related functions that are needed at each end when a message is sent from one party to another party in a network.
Peripheral Component Interconnect - the standard which specifies a computer bus for attaching a peripheral to a computer motherboard.
Layer 1 of the OSI model. The layer concerned with electrical, mechanical, and handshaking procedures over the interface connecting a device to the transmission medium.
Power over Ethernet. A technology (IEEE 802.3af) enabling a standard Category 5 cable to deliver both data and up to 15.4 Watts of power. The standard supports two types of devices: Power Sourcing Equipment (PSE) and Powered Devices (PD). Power Sourcing Equipment provides power to the Powered Devices.
Power over Ethernet Plus. A PoE standard (IEEE 802.3at) that provides up to 25.5 Watts of power to devices.
is a set of procedures to be followed when communicating. In computer science the word algorithm is a synonym for the word procedure so a protocol is to communications what an algorithm is to mathematics.
A troubleshooting feature available on select IMC products. If a strand is unavailable, the device at the receiver end notes the loss of link. The device will stop transmitting data and start sending link pulses. Until a valid link is received, the fiber link LED will be OFF on the device on the receiver side of the fiber strand with the fault while the fiber Link LED on the other unit will blink.
Q-in-Q, also known as stackable VLANs or extra tagging, is a modification to VLAN tagging that allows service providers to support customers with multiple VLAN tags using a single VLAN tag.
Quality of Service. 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.
A device that amplifies, restores or reshapes signals to compensate for distortion and/or attenuation prior to retransmission.
Request for Comments. An RFC is a series of notes on topics concerning the Internet. RFCs can be purely informational, or they can specify a proposed, draft, or approved Internet standard.
A portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. It defines objects for managing Ethernet-like objects.
Specification for the type of connector, holding up to eight wires, used in terminating 10BaseT UTP or STP cabling. RJ-45 plugs and sockets are used in Ethernet and Token Ring devices
A telephone connector that holds up to eight wires. It uses the same plug and socket as RJ-45 but has different pinouts. RJ-48C is commonly used for T1 lines and uses pins 1, 2, 4 and 5.
Remote Monitoring. A network management term. A specification for collecting and reporting advanced network activity data. Data collected using RMON can be used to analyze remote network performance, topology, faults, departmental usage (for accounting) and protocols. Remote Network MONitoring MIB was developed by the Internet Engineering Task Force (IETF) to support monitoring and protocol analysis of Ethernet and Token- Ring LANs. It is an industry standard specification that provides much of the functionality offered by today's proprietary network analyzers and protocol analyzers.
Remote Monitoring 2. The RMON Working Group of the IETF is working on the next generation of RMON known as RMON2. RMON2 moves beyond the segment up to the enterprise network and supplies the information needed for the health and performance monitoring of networked client/server applications and end-to-end communications.
The Restriction of Hazardous Substances in Electrical and Electronic Equipment Directive, passed into law by the European Union. The directive restricts the use of harmful and toxic chemicals. All IMC part numbers starting with “8” are RoHS compliant.
An abbreviation for receive. TX/RX is transmit/receive.
IMC term used to signify a protocol independent mode converter converting from single mode to multi-mode fiber. Typically 850 or 1300nm multi-mode to 1310 or 1550nm single mode.
IMC term used to signify a protocol independent mode converter converting from single mode to single mode fiber. Typically 1310nmn to 1550nm.
Synchronous Data Hierarchy. The European standard for using optical media as the physical transport for high speed long-haul networks.
Small Form-factor Pluggable. A compact optical transceiver used in telecom and datacom applications. It is a popular industry format supported by most fiber optic component vendors. The primary advantages of this approach are hot pluggability, field replacabilty, and mix and match optical reach and type. Also called Mini-GBIC
Small form factor pluggable optical transceiver running at 1.25Gbps
Small form factor pluggable optical transceiver running at 1.25Gbps, featuring extended diagnostics
Small form factor pluggable optical transceiver running at 155Mbps
Small form factor pluggable optical transceiver running at 155Mbps, featuring extended diagnostics
Small form factor pluggable optical transceiver running at 2.4Gbps
Small form factor pluggable optical transceiver running at 2.4Gbps, featuring extended diagnostics
Indicates the presence of two SFP transceiver ports
Single mode fiber is fiber designed to propagate light of only a single wavelength (typically 5-10 microns in diameter).
Simple Network Management Protocol. An application layer protocol that facilitates the exchange of management information between network devices. It is part of the Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite. SNMP allows network administrators to manage network performance, find and solve network problems, and plan for network growth.
Synchronous Optical Network. A North American standard for using optical media as the physical transport for high-speed long-haul networks.
IMC term for single strand fiber carrying a Fast Ethernet signal. Known in the industry as 100Base-BX.
IMC term for single strand fiber carrying a Gigabit Ethernet signal. Known in the industry as 1000Base-BX.
Shielded twisted pair cable
Indicates a fiber connection designed for 100Mbps or 1000Mbps. Derived from the IEEE standards 100BASE-SX and 1000Base-SX. Typically shorter range than FX (100BASE-FX) or LX (1000BASE-LX) fiber.
A digital transmission link with a capacity of 1.544 Mbps used in North America. Typically channelized into 24 DS0s, each capable of carrying a single voice conversation or data stream. Uses two pairs of twisted pair wires. Also called a DS1 line.
A digital transmission service provided at 44.736 Mbps, with a capacity of 45 Mbps, or 28 T1 lines. Also called a DS3 line.
Time Division Multiplexer. A device which divides the time available on its composite link among its channels, usually interleaving bits (Bit TDM) or characters (Character TDM) of data from each terminal.
Abbreviation for telephone company, whether local, independent or national, which can also act or operate as an internet service provider (ISP) or any other entity that provides telephony and/or data communications services. Can also refer to a Local Exchange Carrier (LEC) or communications service provider (CSP).
The virtual terminal protocol in the Internet suite of protocols. It lets users on one host access another host and work as terminal users of that remote host. Instead of dialing into the computer, the user connects to it over the Internet using Telnet. When issuing a Telnet session, it connects to the Telnet host and logs in. The connection enables the user to work with the remote machine as though it were a terminal connected to it.
Trivial File Transfer Protocol. TFTP is a simple form of File Transfer Protocol (FTP) that uses the User Datagram Protocol (UDP) and provides no security features.
Twisted pair - used to refer to 10Mbps (10Base-T) Ethernet connections (see TP/FO, TP-TX/FX)
IMC Term used to describe a 10/100 media and rate converter. Converts from 10 or 100 Mbps copper (10/100BASE-TX) to 100Mbps Fiber (100BASE-FX)
IMC Term used to describe the CWDM version of the TP-TX/FX. (see TP-TX/FX)
IMC Term used to describe the single strand version of the TP-TX/FX. (see TP-TX/FX)
IMC Term used to describe a 10/100 media and rate converter. Converts from 10 or 100 Mbps copper (10/100BASE-TX) to 100Mbps Fiber (100BASE-SX)
IMC Term used to describe a conversion between 10 Mbps twisted pair copper (10BASE-T) and a 50 Ohm BNC 10BASE-2 connection.
IMC Term used to describe a conversion between a twisted pair RJ-48 port (T1/E1) and a fiber optic port. Used for IMC's iMcV-T1/E1 cards.
IMC Term used to describe a 10Mbps (10Base-T) conversion between a twisted pair port and a fiber optic port.
IMC Term used to describe a 10Mbps (10Base-T) conversion between a twisted pair port and a fiber optic port running single strand fiber.
A device consisting of a receiver and a transmitter. Used to convert electrical signals to optical signals and optical signals to electrical signals.
Term used to refer to a twisted pair copper port, or transmit (as in TX/RX)
Transmission Rate.
IMC term used to indicate a copper to CWDM fiber connection (Giga-FiberLinX-II modules only)
IMC term used to indicate the presence of three twisted pair copper ports
IMC term used to indicate the presence of three twisted pair copper ports and a single fiber port
IMC term used to indicate the presence of three twisted pair copper ports and a single strand fiber port
IMC term used to indicate the presence of three twisted pair copper ports and a single fiber port
IMC term used to indicate the presence of four twisted pair copper ports
IMC term used to indicate the presence of four twisted pair copper ports and a single SFP port
IMC term used to indicate the presence of five twisted pair copper ports
IMC term usually used to indicate a fixed rate 100Mbps copper (100Base-TX) to fiber (100Base-FX) conversion. Can also refer to autosensing 10/100 for FiberLinX-II and MediaLinX modules.
IMC term usually used to indicate a fixed rate 1000Mbps copper to fiber conversion. Can also refer to autosensing 10/100/1000 for Giga-FiberLinX-II and Giga-MediaLinX modules.
IMC term used to indicate a product with a twisted pair copper port and an SFP port
IMC term used to indicate the single strand fiber version of the TX/FX products (see TX/FX).
IMC term used to indicate the single strand fiber version of the TX/LX products (see TX/LX).
IMC term used to indicate a copper to fiber conversion. SX can indicate 100BASE-SX or 1000BASE-SX, and the device can be fixed rate or autosensing, depending on the product.
IMC term used to indicate a product with two twisted pair copper ports.
The Unified Management Agent (UMA) allows operators to manage all devices installed in an IMC Networks managed iMediaChassis, with a single IP address, from a central location.
Universal Serial Bus.
Unshielded Twisted Pair Cable. Two wires twisted two or more times per inch in order to help cancel out noise. The entire cable has no covering. UTP cable is typically used in telephone lines for voice service, 10BaseT Ethernet networks and particular sections of Token Ring networks.
Very-high-bit-rate Digital Subscriber Line. Technology that provides faster transmission of both voice and data communication on the same line. VDSL is typically deployed over existing CAT3 or telephone wiring and supports services such as VoIP and general internet access. The performance/speed of VDSL is subject to the physical distance data travels over the cabling.
Virtual LAN. A network architecture which allows geographically distributed users to communicate as if they were on a single physical LAN by sharing a single broadcast and multicast domain.
VLAN tagging provides a mechanism for bridged LANS sharing the same physical infrastructure to create "virtual" LANs. IEEE designed some special Ethernet packets which can be used to inter-connect switches. These packets not only carry the data, but also information as to the VLAN. These special packets are called .Q tagged packets. Also known as 802.1Q.
Voice over IP. Set of facilities for managing the delivery of voice information using the Internet Protocol (IP). Voice information is sent in digital form in discrete packets over the Internet instead of in analog form over the public switched telephone network (PSTN). A major advantage of VoIP is that it avoids the tolls charged by ordinary telephone service.
Wide Area Network. A group of networked computers in a large geographical area of more than 50 Km. The best example of a WAN is the Internet.
Wave Division Multiplexing. An optical transmission technique in which two or more wavelengths (each carrying its own information) are combined for transmission over a single optical fiber. At the receiving end, the wavelengths are separated and directed to separate receivers. Increases the capacity of data transmission over fiber optics. Also used to connect two fiber optic devices over a single strand of fiber.
