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• Modeling can be key to capacity planning

  Planning for the future of your network sometimes requires rigorous planning and modeling. In this tip, Ed Tittel shows how a free modeling tool just may come to your rescue. Continue Reading

• Introduction to IPv6 -- 'IPv6 Security,' Chapter 1

  Learn what the Internet Protocol version 6 (IPv6) is, know who has adopted it, understand the vulnerabilities causing security concerns, and learn methods used to protect networks against hacker attacks and tools. Continue Reading

• How does a firewall work?

  A firewall is a set of related programs, located at a network gateway server, that protects the resources of a private network from users from other networks. An enterprise with an intranet that allows its workers access to the wider Internet ... Continue Reading

• ping

  Ping is a basic Internet program that allows a user to verify that a particular IP address exists and can accept requests. The verb "ping" means the act of using the ping utility or command. Continue Reading

• Seebeck effect

  The Seebeck effect describes the generation of electricity following the connection of two dissimilar electrical conductors or semiconductors that illustrates the thermoelectric effect.  Continue Reading

• Definitions to Get Started

  • fiber to the home (FTTH)
  • Universal Service Fund (USF)
  • Cisco Performance Routing (PfR)
  • 5G

  • Secure Access Service Edge (SASE)
  • VPN (virtual private network)
  • network switch
  • BGP (Border Gateway Protocol)

  View All Definitions

• WAN technologies summarized

  This excerpt from 'The Shortcut Guide to Optimizing WAN Application Delivery' introduces current and existing WAN environments and technologies. Topics include point-to-point links, circuit and packet switching methodologies, virtual circuits, ...Continue Reading

• port interface card (PIC)

  A port interface card (PIC) is a computer circuit board that provides multiple, diverse interfaces for connections to external networks. In effect, a PIC is an enhanced network interface card (NIC)... (Continued)Continue Reading

• Class of Service (CoS)

  Class of Service (CoS) is a way of managing traffic in a network by grouping similar types of traffic (for example, e-mail, streaming video, voice, large document file transfer) together and treating each type as a class with its own level of ...Continue Reading

• Internet Routing in Space (IRIS)

  Internet Routing in Space in Space, also known as (IRIS), is a project being conducted by the U.S. Department of Defense to place an IP (Internet protocol) router on a geostationary satellite... (Continued)Continue Reading

• Trouble connecting to the VPN: Static and dynamic IP address issues

  For mobile or remote employees, a corporate VPN promises simple, secure access to privileged data and resources. But when that access fails, troubleshooting VPN connectivity issues can be frustrating for the end user and networking staff alike. In ...Continue Reading

• phase-change cooling (vapor cooling)

  Phase-change cooling, also called vapor cooling, is a microprocessor-cooling technology that works according to the same principles as a conventional refrigerator, freezer or air conditioner. The principal components of a phase-change cooling system...Continue Reading

• Best practices for securing your wireless LAN

  Perhaps the biggest network security concern for many enterprises is securing a wireless local area network (WLAN). This three-part expert lesson provides best practices for securing a WLAN in the enterprise. Lesson 1 focuses on methods of ...Continue Reading

• cognitive radio (CR)

  Cognitive radio (CR) is a form of wireless communication in which a transceiver can intelligently detect which communication channels are in use and which are not, and instantly move into vacant channels while avoiding occupied ones... (Continued)Continue Reading

• Peltier effect

  The Peltier effect is a temperature difference created by applying a voltage between two electrodes connected to a sample of semiconductor material. This phenomenon can be useful when it is necessary to transfer heat from one medium to another on a ...Continue Reading

• thermoelectric cooling

  Thermoelectric cooling is a way to remove thermal energy from a medium, device or component by applying a voltage of constant polarity to a junction between dissimilar electrical conductors or semiconductors...(continued)Continue Reading

• MDI/MDIX (medium dependent interface/MDI crossover)

  MDI/MDIX is a type of Ethernet port connection using twisted pair cabling.Continue Reading

• master/minion (formerly master/slave)

  In computer networking, master/slave is a model for a communication protocol in which one device or process (known as the master) controls one or more other devices or processes (known as slaves).Continue Reading

• FECN/BECN (forward explicit congestion notification/backward explicit congestion notification)

  In a frame relay network, FECN (forward explicit congestion notification) is a header bit transmitted by the source (sending) terminal requesting that the destination (receiving) terminal slow down its requests for data.Continue Reading

• Carrier Sense Multiple Access/Collision Detect (CSMA/CD)

  Carrier Sense Multiple Access/Collision Detect (CSMA/CD) is the protocol for carrier transmission access in Ethernet networks.Continue Reading

• CSU/DSU (Channel Service Unit/Data Service Unit)

  A CSU/DSU (Channel Service Unit/Data Service Unit) is a hardware device about the size of an external modem that converts a digital data frame from the communications technology used on a local area network (LAN) into a frame appropriate to a ...Continue Reading

• CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance)

  CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) is a protocol for carrier transmission in 802.11 networks.Continue Reading

• TCP/IP offload engine (TOE)

  The TCP/IP offload engine (TOE for short) is a technology that is gaining popularity in high-speed Ethernet systems for the purpose of optimizing throughput.Continue Reading

• traffic engineering

  Traffic engineering is a method of optimizing the performance of a telecommunications network by dynamically analyzing, predicting and regulating the behavior of data transmitted over that network... (Continued)Continue Reading

• Wi-Fi Multimedia (WMM)

  Wi-Fi Multimedia (WMM), previously known as Wireless Multimedia Extensions (WME), is a subset of the 802.11e wireless LAN (WLAN) specification that enhances quality of service (QoS) on a network by prioritizing data packets according to four ...Continue Reading

• NBAR (Network Based Application Recognition)

  Network Based Application Recognition (NBAR) is a mechanism that classifies and regulates bandwidth for network applications to ensure that available resources are utilized as efficiently as possible. Cisco Systems developed NBAR as part of its ...Continue Reading

• 802.11 protocols

  Learn about the newest wireless protocol, 802.11n, as well as how to evaluate which protocol is best for your environment. You also get a run-down of the 802.11a, 802.11b and 802.11g specifications in this guide.Continue Reading

• Networking certification guide

  This networking certification guide covers the majority of networking-related certifications available to IT professionals. Only credentials likely to be recognized as having value within the networking industry have been selected, which led us to ...Continue Reading

• MOSPF (Multicast Open Shortest Path First)

  MOSPF (Multicast Open Shortest Path First) is an extension to the OSPF (Open Shortest Path First) protocol that facilitates interoperation between unicast and multicast routers... (Continued)Continue Reading

• route aggregation

  Route aggregation is an alternate term for route summarization, which is a method used to minimize the number of routing tables required in an IP network.Continue Reading

• route summarization (route aggregation)

  Route summarization, also called route aggregation, is a method of minimizing the number of routing tables in an IP (Internet Protocol) network. It works by consolidating selected multiple routes into a single route advertisement, in contrast to ...Continue Reading

• Network management frameworks: FCAPS and ITIL

  Network management is a complex topic, especially as the network has to handle more instances of unified communications, video, and virtualization. Thus far, two frameworks exist that can be of some use for understanding and taming network ...Continue Reading

• Internet metering

  Internet metering is a service model in which an Internet service provider (ISP) tracks the customer's use of bandwidth and charges accordingly. Typically, the customer selects a service package with a flat rate up to a specified limit and pays,...Continue Reading

• tru2way

  Tru2way is the trade name for a technology that facilitates interactive TV and the convergence of digital television (DTV) with other communications devices... (Continued)Continue Reading

• OA&M (operations, administration, and management)

  OA&M (operations, administration, and management) is a general term used to describe the costs, tasks involved, or other aspects of operating, administering, and managing something such as a computer network.Continue Reading

• LAN server

  A local area network (LAN) server is a program (and by implication usually the computer it runs in) that "serves" the resources (files, storage, application programs, printers, and other devices) for a number of attached workstations.Continue Reading

• Learning Path: Network and Web Site Administration

  NETWORK AND WEB SITE ADMINISTRATION....network operations center (NOC) - internetworking - firewall - proxy server - DMZ - NAT - EGP - BGP - peering - colocation - IGP - DHCP - network operating system - Novell Directory Services (NDS) - nslookup - ...Continue Reading

• Learning Path: Telephony and Wide Area Networks

  TELEPHONY AND WIDE AREA NETWORKS...circuit - PSTN - Plain Old Telephone Service (POTS) - telephone jacks - dial-up - acoustic coupler - modem - 56flex - 56 Kbps (x2) - handshaking - V.xx standards - local loop - central office - LIDB - dedicated ...Continue Reading

• Ethernet Glossary

  After you've finished, you can test your knowledge with Quiz #28: Ethernet.Continue Reading

• IDSL

  IDSL is a system in which digital data is transmitted at 128 Kbps on a regular copper telephone line (twisted pair) from a user to a destination using digital (rather than analog or voice) transmission, bypassing the telephone company's central ...Continue Reading

• Learning Path: Network Infrastructure

  NETWORK INFRASTRUCTURE...infrastructure - backbone - network access point (NAP)- vBNS - Internet 2 - MAE - peering - router - switch - bridge - hub - stackable hub - repeater - brouter - aggregator - gateway - point-of-presence (POP) - colocation - ...Continue Reading

• NIS (Network Information System)

  NIS (Network Information System) is a network naming and administration system for smaller networks that was developed by Sun Microsystems.Continue Reading

• IT Survival Kit: Networking refreshers

  Quick Network Security & Hardware Refreshers School is out for college students across the US, but the learning never stops for IT professionals.Continue Reading

• Optical Carrier levels (OCx)

  The Synchronous Optical Network (SONET) includes a set of signal rate multiples for transmitting digital signals on optical fiber.Continue Reading

• two-way server

  A two-way server is a server that incorporates a multi-core processor for increased performance... (Continued)Continue Reading

• flow routing

  Flow routing is a network routing technology that takes variations in the flow of data into account to increase routing efficiency... (Continued)Continue Reading

• pseudowire

  Pseudowire ( sometimes spelled as pseudo wire or abbreviated as PW) is a mechanism for emulating various networking or telecommunications services across packet-switched networks using Ethernet, IP, or MPLS... (Continued)Continue Reading

• caller ID spoofing

  Caller ID spoofing is a service that allows a caller to masquerade as someone else by falsifying the number that appears on the recipient's caller ID display... (Continued)Continue Reading

• wavelength-division multiplexing (WDM)

  Wavelength-division multiplexing (WDM) is a method of combining multiple signals on laser beams at various infared (IR) wavelengths for transmission along fiber optic media. Each laser is modulated by an independent set of signals. ...Continue Reading

• Firewall implementation: Perimeter security placement and management

  For your enterprise firewall implementation, understand where your perimeter security goes, how many you need, what precautions to be aware of and know how to manage and maintain your firewall.Continue Reading

• How to choose the best firewall for your enterprise

  Learn how to choose the best firewall for your enterprise. This guide gives you purchasing advice, tells you which IT team is responsible for the perimeter security solution and offers a checklist of risks you must assess before making deciding ...Continue Reading

• ELF (extremely low frequency)

  ELF (extremely low frequency) refers to an electromagnetic field having a frequency much lower than the frequencies of signals typically used in communications.Continue Reading

• access point base station

  Access point base station is the original term for what is now known as a femtocell.Continue Reading

• bit stuffing

  Bit stuffing is the insertion of one or more bits into a transmission unit as a way to provide signaling information to a receiver... (Continued)Continue Reading

• Hayes command set

  Hayes command set is a specific programming language originally developed for the Hayes Smartmodem 300 baud modem during the late 1970s... (Continued)Continue Reading

• direct sequence spread spectrum (DSSS) or direct sequence code division multiple access (DS-CDMA)

  Direct sequence spread spectrum, also known as direct sequence code division multiple access (DS-CDMA), is one of two approaches to spread spectrum modulation for digital signal transmission over the airwaves.Continue Reading

• average revenue per user or average revenue per unit (ARPU)

  Average revenue per user or average revenue per unit (ARPU) is an expression of the income generated by a typical subscriber or device per unit time in a telecommunications network... (Continued)Continue Reading

• Wireless protocols learning guide

  Wireless protocols; technologies including 802.11, WLAN, WPA, WEP, Wi-Fi and wireless broadband; and deployment issues such as access points, security and troubleshooting are discussed in this guide designed to provide a basic introduction to ...Continue Reading

• Wireless network deployment and management

  Wireless network deployment and management are discussed in this guide.Continue Reading

• Wireless troubleshooting

  Wireless network troubleshooting basics are discussed in this guide.Continue Reading

• Wireless access points

  The basics of wireless access point (AP) as well as configuration and placement are covered in this guide.Continue Reading

• Developing good troubleshooting technique -- from 'Network troubleshooting and diagnostics'

  The most important part of troubleshooting is developing a good technique. This excerpt from "Network troubleshooting and diagnostics" lays the foundation for developing a good technique by examining approaches such as using the OSI model as a ...Continue Reading

• Network engineering applications -- from 'Network troubleshooting and diagnostics'

  Learn about network engineering and analysis applications that can be used when a high-level approach is needed to understand how the network system as a whole operates, both within each individual device and between the internal network and any ...Continue Reading

• IP address management -- from 'Network troubleshooting and diagnostics'

  Learn how IP address management and maintenance tools can help manage the scope of IP addresses on your network. With typical Class C subnets consuming upwards of 254 addresses per subnet and most companies needing multiple subnets, the sheer ...Continue Reading

• Tool suites for identifying the problem -- from 'Network troubleshooting and diagnostics'

  A baker can't bake a cake without a good cake pan, and a mechanic won't get very far in fixing your car without a solid wrench set. Though the tools for network administrators are different and more difficult to wrap your hands around than these ...Continue Reading

• Network troubleshooting and diagnostics: Introduction

  Network troubleshooting and diagnostics begins with realizing that there is a problem and then finding out what that problem really is. Once you know the root cause of the problem, the resolution is usually a Google search away. But finding that ...Continue Reading

• 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

• 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

• 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

• 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