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Bring yourself up to speed with our introductory content.

  • comfort noise generator (CNG)

    A comfort noise generator (CNG) is a program used to generate background noise artificially for voice communications during periods of silence that occur during the course of conversation... (Continued) Continue Reading

  • netstat

    Netstat is a common command line TCP/IP networking utility available in most versions of Windows, Linux, UNIX and other operating systems... (Continued) Continue Reading

  • Ethernet as a service (EaaS)

    Ethernet as a service (EaaS) is the use of high-bandwidth, fiber optic media such as Packet over SONET (PoS) to deliver 10 Mbps, 100 Mbps or even 1000 Mbps Ethernet service to one or more customers across a common bidirectional broadband ... Continue Reading

  • Cisco Information Security Specialist (CISS)

    Cisco Information Security Specialist (CISS) is an entry-level certification attesting that the holder has demonstrated the foundational knowledge and skills required to install and support a Cisco Self-Defending Network... (Continued) Continue Reading

  • network coding

    Network coding is a method of optimizing the flow of digital data in a network by transmitting digital evidence about messages... (Continued) Continue Reading

  • quadruple-play network

    A quadruple-play network is one that offers mobility in addition to the voice, data and video provided by a triple play network.Continue Reading

  • Carrier Ethernet

    Carrier Ethernet is the use of high-bandwidth Ethernet technology for Internet access and for communication among business, academic and government local area networks (LANs)... (Continued)Continue Reading

  • video on demand (VoD)

    Video on demand (VoD) is an interactive TV technology that allows subscribers to view programming in real time or download programs and view them later... (Continued)Continue Reading

  • multichassis multilink PPP (MMP)

    Multichassis multilink PPP (MMP) is an extension of multilink PPP (MP) in which the subscriber can consist of more than one computer... (Continued)Continue Reading

  • triple-play network

    A triple-play network is one in which voice, video and data are all provided in a single access subscription... (Continued)Continue Reading

  • multilink PPP

    Multilink PPP is a communications protocol that enables a personal computer (PC) to use two PPP (Point-to-Point Protocol) communications ports as if they were a single port of greater bandwidth... (Continued)Continue Reading

  • operational support system (OSS)

    An operational support system (OSS) is a set of programs that help a communications service provider monitor, control, analyze and manage a telephone or computer network.Continue Reading

  • DSLAM (Digital Subscriber Line Access Multiplexer)

    A DSLAM (Digital Subscriber Line Access Multiplexer) is a network device, usually at a telephone company central office, that receives signals from multiple customer Digital Subscriber Line (DSL) connections and puts the signals on a high-speed ...Continue Reading

  • point-of-presence (POP)

    On the Internet, a point-of-presence (POP) is an access point from one place to the rest of the Internet.Continue Reading

  • backbone

    A backbone is a larger transmission line that carries data gathered from smaller lines that interconnect with it.Continue Reading

  • cable TV or CATV (community antenna television)

    Cable TV is also known as "CATV" (community antenna television).Continue Reading

  • T-carrier system

    To see the relationship between T-carrier, E-carrier, and DS0 multiples, see digital signal X. The T-carrier system, introduced by the Bell System in the U.S. in the 1960s, was the first successful system that supported digitized voice transmission.Continue Reading

  • peering

    Peering is the arrangement of traffic exchange between Internet service providers (ISPs).Continue Reading

  • carrier signal

    A carrier signal is a transmitted electromagnetic pulse or wave at a steady base frequency of alternation on which information can be imposed by increasing signal strength, varying the base frequency, varying the wave phase, or other means... (...Continue Reading

  • ROADM (reconfigurable optical add-drop multiplexer)

    An ROADM (reconfigurable optical add-drop multiplexer) is a device that can add, block, pass or redirect modulated infrared (IR) and visible light beams of various wavelengths in a fiber optic network. ... (Continued)Continue Reading

  • IP Multimedia Subsystem (IMS)

    The IP Multimedia Subsystem (IMS) is a concept for an integrated network of telecommunications carriers that would facilitate the use of IP (Internet Protocol) for packet communications in all known forms over wireless or landline... (Continued)Continue Reading

  • broadband

    In general, broadband refers to telecommunication in which a wide band of frequencies is available to transmit information.Continue Reading

  • inverse multiplexing over ATM (IMA)

    Inverse multiplexing over ATM (IMA) is a method of optimizing the data transfer rate for individual subscribers in networks that use asynchronous transfer mode (ATM) by dividing the data into multiple concurrent streams that are sent across separate...Continue Reading

  • telecom carrier

    A telecom carrier is a company that is authorized by regulatory agencies to operate a telecommunications system.Continue Reading

  • carrier detect

    Carrier detect (see modem lights) is a control signal between a modem and a computer that indicates that the modem detects a "live" carrier that can be used for sending and receiving information.Continue Reading

  • Cisco CCIP MPLS certification: Introduction

    Learn skills required for the MPLS portion of the Cisco CCIP certification. These skills are tested in the CCIP 642-611 -- Implementing Cisco MPLS Exam.Continue Reading

  • erlang

    The Erlang programming language is not the same thing as the erlang, a unit of traffic density.Continue Reading

  • Cisco certification

    This Cisco certifications guide covers CCNA, CCNP, CCIE and more. Decide whether getting a Cisco certification is necessary for your career, which one you should get and how to study and pass your exam.Continue Reading

  • fiber jumper

    A fiber jumper, sometimes called a fiber patch cord is a length of fiber cabling fitted with LC, SC, MTRJ or ST connectors at each end... (Continued)Continue Reading

  • patch cord

    A patch cord is a length of cable, with connectors on the ends, that is used to connect an end device to something else, such as a power source.Continue Reading

  • staggered quadrature phase-shift keying

    Staggered quadrature phase-shift keying (SQPSK), also known as offset quadrature phase-shift keying (OQPSK), is a method of phase-shift keying (PSK) in which the signal carrier-wave phase transition is always 90 degrees or 1/4 cycle at a time... (...Continue Reading

  • KVM switch (keyboard, video, mouse switch)

    A KVM (keyboard, video, mouse) switch is a hardware device that allows a user to control multiple computers from a single keyboard, video display monitor and mouse.Continue Reading

  • concentrator

    As generally used, a concentrator is a device that acts as an efficient forwarder of data transmission signals.Continue Reading

  • flooding

    In a network, flooding is the forwarding by a router of a packet from any node to every other node attached to the router except the node from which the packet arrived.Continue Reading

  • Audiobook: Intrusion Prevention Fundamentals

    Intrusion Prevention Fundamentals: An introduction to network attack mitigation with IPSContinue Reading

  • AppleTalk

    AppleTalk is a set of local area network communication protocols originally created for Apple computers.Continue Reading

  • AMTOR (amateur teleprinting over radio)

    AMTOR (amateur teleprinting over radio) is a digital communications method used by radio amateurs, in which the frequency of errors is reduced by handshaking or character repetition.Continue Reading

  • automatic repeat request (ARQ)

    Automatic repeat request (ARQ) is a protocol for error control in data transmission.Continue Reading

  • IS-IS (Intermediate System-to-Intermediate System protocol)

    One of the most commonly used routing protocols, the Intermediate System-to-Intermediate System protocol (IS-IS) is based on a routing method known as DECnet Phase V routing, in which routers known as intermediate systems exchange data about routing...Continue Reading

  • autotrunking

    Autotrunking is a function that can be activated for one or more switch ports in a Cisco system of virtual local area networks (VLANs), making those ports capable of carrying traffic for any or all of the VLANs accessible by a particular switch....Continue Reading

  • virtual systems management (VSM)

    Virtual systems management (VSM), also known as virtual system management, is the process of remotely managing the allocation and use of resources in conventional networks as well as in virtual area networks (VANs), virtual private networks (VPNs), ...Continue Reading

  • GVRP (GARP VLAN Registration Protocol or Generic VLAN Registration Protocol)

    GVRP (GARP VLAN Registration Protocol or Generic VLAN Registration Protocol) is a protocol that facilitates control of virtual local area networks (VLANs) within a larger network . GVRP conforms to the IEEE 802.1Q specification, which defines a ...Continue Reading

  • VxWorks

    VxWorks is a real-time operating system (RTOS) that can be used in embedded systems... (Continued)Continue Reading

  • Network administration guide

    Good network administration is the backbone of today's technology-dependent enterprises. Network administrators are charged with keeping expansive networks and numerous applications running smoothly, and the job can seem overwhelming at times. We're...Continue Reading

  • tunneling or port forwarding

    Tunneling is the transmission of data intended for use only within a private, usually corporate network through a public network in such a way that the routing nodes in the public network are unaware that the transmission is part of a private ...Continue Reading

  • BGAN (Broadband Global Area Network)

    BGAN (Broadband Global Area Network) is a mobile communications system created to transmit broadband wireless voice and data communications almost anywhere on the earth's surface.Continue Reading

  • Metcalfe's Law

    Metcalfe's Law is expressed in two general ways: The number of possible cross-connections in a network grow as the square of the number of computers in the network increases.Continue Reading

  • wildcard mask

    A wildcard mask is a sequence of numbers that streamlines packet routing within the subnets of a proprietary network... (Continued)Continue Reading

  • fixed-length subnet mask (FLSM)

    A fixed-length subnet mask (FLSM) is a sequence of numbers of unchanging length that streamlines packet routing within the subnets of a proprietary network... (Continued)Continue Reading

  • Managing Windows networks using scripts -- The basics

    Learning to use scripts can make the life of a network administrator a lot easier by allowing you to automate daily administration tasks. This tip begins a series on using scripts to manage Windows networks.Continue Reading

  • baseboard management controller (BMC)

    A baseboard management controller (BMC) is a specialized service processor that monitors the physical state of a computer, network server or other hardware device using sensors and communicating with the system administrator through an independent ...Continue Reading

  • packet loss

    Packet loss is the failure of one or more transmitted packets to arrive at their destination... (Continued)Continue Reading

  • Traversal Using Relay NAT (TURN)

    Traversal Using Relay NAT (TURN) is a protocol, currently at the working draft stage, that is intended to govern the reception of data over a Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) connection by a single communications ...Continue Reading

  • delay-tolerant network

    A delay-tolerant network is a network designed to operate effectively over extreme distances such as those encountered in space communications or on an interplanetary scale... (Continued)Continue Reading

  • logical router

    A logical router is a configured partition of a traditional network hardware, or "physical," router.Continue Reading

  • Certified Wireless Networking Professional (CWNP)

    Certified Wireless Networking Professional (CWNP)is the name for the family of wireless certifications from Planet3Wireless.Continue Reading

  • CDPD (Cellular Digital Packet Data)

    CDPD (Cellular Digital Packet Data) is a specification for supporting wireless access to the Internet and other public packet-switched networks.Continue Reading

  • UHF (ultrahigh frequency)

    The UHF (ultrahigh frequency) range of the radio spectrum is the band extending from 300 MHz to 3 GHz.Continue Reading

  • VHF (very high frequency)

    The VHF (very high frequency) range of the radio spectrum is the band extending from 30 MHz to 300 MHz.Continue Reading

  • infrared transmission

    Infrared transmission refers to energy in the region of the electromagnetic radiation spectrum at wavelength s longer than those of visible light, but shorter than those of radioContinue Reading

  • iDEN (Integrated Digital Enhanced Network)

    iDEN (Integrated Digital Enhanced Network) is a wireless technology from Motorola combining the capabilities of a digital cellular telephone, two-way radio, alphanumeric pager and data/fax modem in a single network.Continue Reading

  • GTAG (Global Tag)

    GTAG (Global Tag) is a standardization initiative of the Uniform Code Council (UCC) and the European Article Numbering Association (EAN) for asset tracking and logistics based on radio frequency identification (RFID).Continue Reading

  • CTI (computer-telephony integration)

    CTI (computer-telephony integration), or sometimes simply "computer telephony," is the use of computers to manage telephone calls.Continue Reading

  • SIGTRAN (Signaling Transport)

    SIGTRAN (for Signaling Transport) is the standard telephony protocol used to transport Signaling System 7 (SS7) signals over the Internet.Continue Reading

  • virtual area network (VAN)

    A virtual area network (VAN) is a network on which users are enabled to share a more visual sense of community through high band-width connections.Continue Reading

  • virtual private LAN service (VPLS)

    Virtual private LAN service (VPLS) is a technology that makes it possible to connect geographically dispersed local area networks (LANs) logically over the Internet.Continue Reading

  • GMPLS (Generalized Multiprotocol Label Switching or Multiprotocol Lambda Switching)

    GMPLS (Generalized Multiprotocol Label Switching), also known as Multiprotocol Lambda Switching, is a technology that provides enhancements to Multiprotocol Label Switching (MPLS) to support network switching for time, wavelength, and space ...Continue Reading

  • hardware VPN

    A hardware VPN is a virtual private network ( VPN) based on a single, stand-alone device.Continue Reading

  • extranet

    An extranet is a private network that uses Internet technology and the public telecommunication system to securely share part of a business's information or operations with suppliers, vendors, partners, customers, or other businesses.Continue Reading

  • Layer Two Tunneling Protocol (L2TP)

    Layer Two Tunneling Protocol (L2TP) is an extension of the Point-to-Point Tunneling Protocol (PPTP) used by an Internet service provider (ISP) to enable the operation of a virtual private network (VPN) over the Internet.Continue Reading

  • virtual routing and forwarding (VRF)

    Virtual routing and forwarding (VRF) is a technology included in IP (Internet Protocol) network routers that allows multiple instances of a routing table to exist in a router and work simultaneously.Continue Reading

  • routing table

    A routing table is a set of rules, often viewed in table format, that is used to determine where data packets traveling over an Internet Protocol (IP) network will be directed.Continue Reading

  • hardware load-balancing device (HLD)

    A hardware load-balancing device (HLD), also known as a layer 4-7 router, is a physical unit that directs computers to individual servers in a network, based on factors such as server processor utilization, the number of connections to a server, or ...Continue Reading

  • WAN interface card (WIC)

    A WAN interface card, or WIC, is a specialized network interface card (NIC) that allows devices to connect to a wide area network.Continue Reading

  • split horizon

    Split horizon is a method of preventing a routing loop in a network.Continue Reading

  • route poisoning

    Route poisoning is a method of preventing a network from sending packets through a route that has become invalid.Continue Reading

  • reverse DNS (rDNS)

    Reverse DNS (rDNS) is a method of resolving an IP address into a domain name, just as the domain name system (DNS) resolves domain names into associated IP addresses.Continue Reading

  • start of authority record

    A start of authority (SOA) record is information stored in a domain name system (DNS) zone about that zone and about other DNS records.Continue Reading

  • core router

    A core router is a router that forwards packets to computer hosts within a network (but not between networks).Continue Reading

  • CRC-4 (Cyclic Redundancy Check 4)

    CRC-4 (Cyclic Redundancy Check 4) is a form of cyclic redundancy checking (a method of checking for errors in transmitted data) that is used on E-1 trunk lines.Continue Reading

  • segmentation and reassembly (SAR)

    In a packet-switched telecommunication network, segmentation and reassembly (SAR, sometimes just referred to as segmentation) is the process of breaking a packet into smaller units before transmission and reassembling them into the proper order at ...Continue Reading

  • home agent

    In Mobile Internet Protocol (Mobile IP), a home agent is a router on a mobile node's home network that maintains information about the device's current location, as identified in its care-of address.Continue Reading

  • red route

    A red route is one of three categories of Internet route states defined by the Policy Analysis of Internet Routing (PAIR) project, an initiative dedicated to the development of tools that ISPs (Internet service providers), network operators, and end...Continue Reading

  • PAIR (Policy Analysis of Internet Routing)

    The Policy Analysis of Internet Routing (PAIR) project is a Merit Network initiative dedicated to developing tools that Internet service providers (ISPs), network operators, and end users can use to troubleshoot Internet routing and policy problems.Continue Reading

  • green route

    A green route is one of three categories of Internet route states defined by the Policy Analysis of Internet Routing (PAIR) project, an initiative dedicated to the development of tools that ISPs (Internet service providers), network operators, and ...Continue Reading

  • grey route

    A grey route is one of three categories of Internet routes defined by the Policy Analysis of Internet Routing (PAIR) project, an initiative dedicated to the development of tools that ISPs (Internet service providers), network operators, and end ...Continue Reading

  • cross-bar switch

    In a network, a cross-bar switch is a device that is capable of channeling data between any two devices that are attached to it up to its maximum number of ports.Continue Reading

  • mrouter (multicast router)

    An mrouter, or multicast router, is a router program that distinguishes between multicast and unicast packets and determines how they should be distributed along the Multicast Internet (sometimes known as the Multicast Backbone or MBone).Continue Reading

  • one-armed router

    A one-armed router is a router that routes traffic between virtual local area networks (VLANs).Continue Reading

  • dynamic port numbers (private port numbers)

    The dynamic port numbers (also known as the private port numbers) are the port numbers that are available for use by any application to use in communicating with any other application, using the Internet's Transmission Control Protocol (TCP) or the ...Continue Reading

  • NWay

    NWay is a telecommunications protocol used with Ethernet networking devices (such as router and switch) to automatically negotiate the highest possible common transmission speed between two devices.Continue Reading

  • Molex

    In business since 1938, Molex manufactures electronic, electrical, and optical fiber connectors.Continue Reading

  • routing switch

    In a network, a 'routing switch' is a device that combines the functions of a switch, which forwards data by looking at a physical device address, and a router, which forwards packets by locating a next hop address.Continue Reading

  • near-end crosstalk (NeXT)

    Also see NeXT, a computer company that developed a personal computer with an advanced user interface and operating system.Continue Reading

  • ATM (asynchronous transfer mode)

    ATM (asynchronous transfer mode) is a dedicated-connection switching technology that organizes digital data into 53-byte cell units and transmits them over a physical medium using digital signal technology.Continue Reading

  • High-Speed Serial Interface (HSSI)

    High-Speed Serial Interface (HSSI) is a short-distance communications interface that is commonly used to interconnect routing and switching devices on local area networks (LANs) with the higher-speed lines of a wide area network (WAN).Continue Reading

  • autonomous system (AS)

    On the Internet, an autonomous system (AS) is the unit of router policy, either a single network or a group of networks that is controlled by a common network administrator (or group of administrators) on behalf of a single administrative entity (...Continue Reading

  • stackable hub

    A stackable hub is a hub designed to be connected and stacked or positioned on top of another hub, forming an expanding stack.Continue Reading

  • unicast

    Unicast is communication between a single sender and a single receiver over a network.Continue Reading

  • split

    Among Internet Relay Chat (IRC) users, a split is a condition where two or more IRC servers are temporarily unable to communicate.Continue Reading

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