802.11n is the next Wi-Fi generation. It is a technology that combines multiple antennas, cleverer encoding, and an optional doubling of spectrum to achieve raw data rates up to 600 Mbps. After much debate and a lot of contention among the overall IEEE membership, the all-important IEEE 802.11n working group has given its stamp of approval to the next draft version of the specification. Temporarily dubbed draft version 1.10, it will go out as version 2.0 when it is released to the full IEEE 802.11n committee, about 400 strong, by the end of January 2007. The 2.0 draft spec is expected to be mailed to the membership for comments and voting by the end of January. Voting is expected to be completed on version 2.0 by the end of March with a new draft, version 3.0, ready by the end of May. Benefits of 802.11n include higher throughput (about 120Mbps real world) than the current standard and a range that's 50 percent longer. Also, because of its multiple antennas that can stitch together a fractured signal, it eliminates many indoor spots where the signal would normally be dropped.
The physical gateway between a customer's local loop and the frame relay network
A device used to boost the strength of an electronic or optical signal, which is weakened (attenuated) as it passes through the transport network. Amplifiers add gain to the signal by an amount equal to the loss in the previous section of the network since last amplification.
Asymmetric Digital Subscriber Line (ADSL)
ADSL is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. It does this by utilizing frequencies that are normally not used by a voice telephone call, in particular, frequencies higher than normal human hearing. This signal will not travel very far over normal telephone cables, so ADSL can only be used over short distances, typically less than 5 km. Once the signal reaches the telephone company's local office, the ADSL signal is stripped off and immediately routed onto a conventional internet network, while any voice-frequency signal is switched into the conventional phone network. This allows a single telephone connection to be used for both ADSL service and voice calls at the same time.
Asynchronous Transfer Mode (ATM)
A method of sending audio, visual and computer data at the same time over one high-speed digital line
Atlantic Crossing (AC-1)
Part of the Global Crossing network. AC-1 links the United States, United Kingdom, Netherlands and Germany. It became operational in May 1998.
Capacity on terrestrial fiber optic cables from undersea cable landing stations to metropolitan areas
A range of frequencies between two defined limits
A measure of capacity of information-carrying capacity on a communications channel. Narrowband: Less than or equal to 64 Kbps. Wideband: Digital rates between 64 Kbps and 1.544 Mbps (DSI) or 2.048 Mbps (E1)-LANs, bulk files transfer, video conferencing, and multimedia. Broadband: Greater than 44.736 Mbps (D3) or 34.368 Mbps (E3).
Bidirectional Line Switched Ring (BLSR)
Commonly referred to as BLSR. It is a method of SONET transport in which half of the working network is sent counterclockwise over one fiber and the other half is sent clockwise over another fiber. BLSR offers bandwidth use advantages for distributed traffic in single-ring architectures.
A binary unit of information that can have either of two values, 0 or 1. Contraction of binary digit: kilobit = 1,000 bits; megabit = 1 million bits; gigabit = 1 billion bits; terabit = 1 trillion bits.
Border Gateway Protocol (BGP)
A routing protocol used in inter-domain routing in large networks to maintain integrity of the network. It allows the routers to exchange only pre-specified information with pre-specified routers in other domains.
A data communications device that connects two or more network segments and forwards packets between them. It also amplifies the carrier signal, and accepts data packets, (perhaps buffering them during periods of network congestion) and forwards them.
A transmission channel usually carrying a tremendous amount of information at transmission speeds of 45 Mbps (45,000,000 bits per second) or greater. A communications channel with a bandwidth sufficiently large to carry voice, data and video on a signal channel. Any voice communications channel having a bandwidth greater than a voice-grade channel.
A way of doing data transmission, usually faster than normal transmission mode, in which a continuous block is transferred between main memory and an input/output device without interruption until the transfer has been completed. Characteristically, burst mode is sustainable for only limited periods of time under special conditions.
The information-carrying ability of a telecommunications system, as defined by its design (number of fibers, system length, and optoelectronic equipment) and its deployed equipment (amount of optoelectronics in the station) and measured in bits per second. Capacity is sold in discrete units, usually system interface levels such as DS-3s and STM-1s, that in the aggregate are the equivalent of total system capacity.
A third-party provider of communications services by wire, fiber or radio. Common Carrier: A private company offering facilities or services to the general public on a non-discriminatory basis and regulated as to market entry, practices, and rates by various Federal and State authorities. Private Carrier: Services provided for internal use and free of most common carrier regulations to allow discrimination in service provision or pricing.
Challenge-Handshake Authentication Protocol (CHAP)
An authentication method that can be used when connecting to an Internet Service Provider. CHAP allows you to log in to your provider automatically, without the need for a terminal screen.
The process of subdividing the bandwidth of a circuit into smaller increments called channels. Typically, each channel carries an individual transmission, e.g., a voice conversation, a data conversation, or a computer-to-computer session. This process is accomplished through a multiplexer, such as dense wavelength division multiplexers.
Algorithm that minimizes the redundancy in the signal to be transmitted.
The process of concealing the contents of a message from all except those who know the key. Cryptography is used to protect e-mail messages, credit card information, and corporate data. As the Internet and other forms of electronic communication become more prevalent, electronic security is also becoming increasingly important.
Refers to a virtual channel in a fiber optic system utilizing DWDM. Each virtual channel is supported through a specific wavelength of light, with many channels riding over the same fiber. Once the fiber system is deployed and the DWDM equipment is activated, some of the wavelengths may be activated immediately and others may be left dark for future needs. When the need arises, those dark wavelengths are lit up.
Dense Wavelength Division Multiplexing (DWDM)
A technique which employs more than one light source and detector operating at different wavelengths and simultaneously transmits optical signals through the same fiber while message integrity of each signal is preserved.
Describes a method of storing, processing and transmitting information through the use of distinct electronic or optic pulses representing the binary digits 0 and 1. In communications they will modify a carrier at a selected frequency. The precise signal transitions preclude any distortion such as graininess or snow in the case of video transmission, or static or other background distortion in the case of audio transmission.
Method of storing, processing and transmitting information through the use of distinct electronic or optical pulses that represent the binary digits 0 and 1. Digital transmission and switching technologies employ a sequence of these pulses to represent information as opposed to a continuously variable analog signal. The precise digital numbers preclude any distortion such as graininess or snow in the case of video transmission, or static or other background distortion in the case of audio transmission.
Various impurities may be added to silica-based fiber optic strands as they are constructed to achieve specifically desired transmission or physical properties.
A digital transmission hierarchy supporting 1.544 million bits per second that may be used for "near-full motion" or compressed video, data or voice circuits (24, 48, or 96).
Similar to the North American T-1, E-1 is the European format for digital transmission. E-1 carries signals at 2.048 Mbps (32 channels at 64 Kbps), versus the T-1, which carries signals at 1.544 Mbps (24 channels at 64 Kbps). E-1 and T-1 lines may be interconnected for international use.
Economies of integration
Economies of integration arise from three sources: (1) from postponing some activities until an order is placed, (2) from more precise information about market demands and (3) from the ability to increase loyalty by directly interacting with each customer.
In cryptography, encryption is the process of obscuring information to make it unreadable without special knowledge, sometimes referred to as scrambling. Encryption has been used to protect communications for centuries, but only organizations and individuals with an extraordinary need for secrecy had made use of it. In the mid-1970s, strong encryption emerged from the sole preserve of secretive government agencies into the public domain, and is now used in protecting widely-used systems, such as Internet e-commerce, mobile telephone networks and bank automatic teller machines.
Encryption can be used to ensure secrecy, but other techniques are still needed to make communications secure, particularly to verify the integrity and authenticity of a message; for example, a message authentication code (MAC) or digital signatures. Another consideration is protection against traffic analysis.
Encryption or software code obfuscation is also used in software copy protection against reverse engineering, unauthorized application analysis, cracks and software piracy used in different encryption or obfuscating software.
Erbium-Doped Fiber Amplifier (EDFA)
A purely optical (as opposed to electronic) device used to boost an optical signal. It contains several meters of glass fiber doped with erbium ions. When the erbium ions are excited to a high energy state, the doped fiber changes from a passive medium to an active amplifying medium.
The ability of a system to respond gracefully to an unexpected hardware or software failure. There are many levels of fault tolerance, the lowest being the ability to continue operation in the event of a power failure.
The number of route kilometers installed multiplied by the number of fiber strands along the path
Technology based on thin filaments of glass or other transparent materials used as the medium for transmitting coded light pulses that represent data, image and sound. Fiber-optic technology offers extremely fast transmission speeds.
A firewall is an information technology (IT) security device which is configured to permit, deny or proxy data connections set and configured by the organization's security policy. Firewalls can either be hardware and/or software based.
A firewall's basic task is to control traffic between computer networks with different zones of trust. Typical examples are the Internet which is a zone with no trust and an internal network which is (and should be) a zone with high trust. The ultimate goal is to provide controlled interfaces between zones of differing trust levels through the enforcement of a security policy and connectivity model based on the least privilege principle and separation of duties.
A firewall is also called a Border Protection Device (BPD) in certain military contexts where a firewall separates networks by creating perimeter networks in a Demilitarized zone (DMZ). In a BSD context they are also known as a packet filter. A firewall's function is analogous to firewalls in building construction.
Proper configuration of firewalls demands skill from the firewall administrator. It requires considerable understanding of network protocols and of computer security. Small mistakes can render a firewall worthless as a security tool.
The simultaneous transmission of data in both directions, used when communicating between two computers. Full duplex is sometimes called "Echo On" by some communications programs.
Gbps (Gigabits per second)
A data rate of 1 Gbps corresponds to 1,000 million bits per second.
High Performance Parallel Interface (HIPPI)
HIPPI is used to network supercomputers, high-end workstations and peripherals using cross-bar type circuit switches. It provides for transfer rates of 800 Mbps over 32 twisted pair copper wires (single HIPPI) and 1,600 Mbps over 64 pairs (double HIPPI).
Indefeasible Right of Use (IRU)
A measure of currency in the undersea cable business. The owner of an IRU has the right to use the capacity for the time and bandwidth to which the IRU applies.
International Telecommunication Union (ITU)
The ITU is an intergovernmental agency of the United Nations within which the public and private sectors cooperate for the development of telecommunications. The ITU adopts international regulations governing the use of the radio spectrum and develops standards to facilitate the interconnection of telecommunications systems on a worldwide basis. It is headquartered in Geneva, Switzerland. In 1996, the ITU comprised 185 Member States and 363 members (scientific and industrial companies, public and private operators, broadcasters, regional and international organizations active in three sectors: Radio communications, Standardization and Development).
A fabric of interconnected computer networks, originally known as the DARPA network (Defense Advanced Research Projects Agency) connecting government and academic sites. It currently links about 50 million people worldwide who use it for everything from scientific research to simple e-mail.
Internet Protocol (IP) Address
An Internet address that is a unique number consisting of four parts separated by dots, sometimes called a "dotted quad." For example, 18.104.22.168. Every Internet computer has an IP address and most computers also are assigned one or more domain names that are easier to remember than the dotted quad.
Internet Service Provider.
The 11th letter of the Greek alphabet. Lambda is used as the symbol for wavelength in light wave systems. Fiber optic systems use multiple wavelengths of light through dense wavelength division multiplexing (DWDM). Each range of wavelength appears in a "window" roughly corresponding to a color in the visible light spectrum.
A local area network (LAN) is a computer network covering a local area, like a home, office, or group of buildings. Current LANs are most likely to be based on switched IEEE 802.3 Ethernet technology, running at 10, 100 or 1,000 Mbit/s, or on Wi-Fi technology. Each node or computer in the LAN has its own computing power but it can also access other devices on the LAN subject to the permissions it has been allowed. These could include data, the more expensive devices / less used resources that it would be impractical to have multiple copies of, and the ability to communicate or chat with other users in the network.
The defining characteristics of LANs, in contrast to WANs (wide area networks), are: their much higher data rates, smaller geographic range, and that they do not require leased telecommunication lines.
The amount of time it takes a packet to travel from source to destination. Together, latency and bandwidth define the speed and capacity of a network.
The physical facility, leased from a local exchange carrier (LEC), which provides connectivity between the customer's location and the carrier's point of presence.
Low Voltage Differential Signaling (LVDS)
A low noise, low power, low amplitude method for high-speed (gigabits per second) data transmission over copper wire
Mass customization refers to a customer co-design processof products and services which meet the needs of each individual customer with regard to certain product features. All operations are performed within a fixed solution space, characterized by stable but still flexible and responsive processes. As a result, the costs associated with customization allow for a price level that does not imply a switch in an upper market segment.
Media Gateway Control Protocol (MGCP)
A proposed control and signal standard for the conversion of audio signals carried on telephone circuits to data packets carried over the Internet or other packet networks. Unlike regular phones, IP phones and devices are not fixed to a specific switch, so they must contain processors that enable them to function independently from a central switching location. MGCP eliminates the need for complex, processor-intense IP telephony devices, thus simplifying and lowering the cost of these terminals.
Megabits per second (Mbps)
One Mbps corresponds to a data rate of 1,000,000 bits per second.
Multiple Input/Multiple Output (MIMO) is an area of intense development in the wireless industry because it delivers profound gains in range, throughput and reliability. As a result, manufacturers of wireless local area network (WLAN), wireless metropolitan area network (WMAN), and mobile phone equipment are embracing MIMO technology. However, not all manufacturers claiming MIMO or MIMO benefits are using the term as defined and understood by the majority of researchers in industry and academia. By wrongly invoking the term “MIMO” vendors obscure a momentous technological development.
The ability of one network node to send identical data to a number of end servers on the multicast backbone. For large amounts of data, IP multicasting is more efficient than normal Internet transmissions because the server can broadcast a message to multiple recipients simultaneously.
Multilink Point-to-Point Protocol (MP)
MP allows multiple physical connections between two points to be combined into a single logical connection called a bundle. MP supports dynamic bandwidth allocation, which means that physical links can be added or removed from the bundle as needed.
The electronic conversation between two or more people or groups of people in different places using two or more types of digitally integrated communication for voice, sound, text, data, graphics, video, image or presence at the same time. Applications include conferencing, presentations, training, referencing, games, etc.
An electronic or optical process that combines two or more lower bandwidth transmissions onto one higher bandwidth signal by splitting the total available bandwidth into narrower bands (frequency division) or by allotting a common channel to several transmitting sources one at a time in sequence (time division).
Pertaining or referring to a communications line to which three or more stations are connected. It implies that the line physically extends from one station to another until all are connected.
MultiProtocol Label Switching (MPLS)
MPLS is a widely supported method of speeding up data communication over combined IP/ATM networks. This improves the speed of packet processing and enhances performance of the network.
Nondestructive testing (NDT) has been defined as comprising those test methods used to examine an object, material or system without impairing its future usefulness. The term is generally applied to non-medical investigations of material integrity.
Nondestructive testing is used to investigate the material integrity of the test object. A number of other technologies - for instance, radio astronomy, voltage and amperage measurement and rheometry (flow measurement) - are nondestructive but are not used to evaluate material properties specifically. Nondestructive testing is concerned in a practical way with the performance of the test piece - how long may the piece be used and when does it need to be checked again? Radar and sonar are classified as nondestructive testing when used to inspect dams, for instance, but not when they are used to chart a river bottom.
Thin filaments of glass through which light beams are transmitted. Enormous capacity, low-cost, low-power consumption, small space, lightweight, insensitivity to electromagnetic interference characterize this transport media.
Generic term for a bundle of data, organized in a specific way for transmission. A packet consists of the data to be transmitted and certain control information, including the destination address.
A process where messages are broken into finite-sized packets that are always accepted by the network. The message packets are sent across different circuit paths. The packets are reassembled into the original message at the end of the circuit.
In networking, pipelining is a technique used at the transport layer or data link layer in a layered network architecture that allows for the transmission of multiple frames without waiting to see if they are acknowledged on an individuals basis.
Point of Presence (POP)
The physical location within a LATA where an inter-exchange carrier's circuit interconnects with the local lines of telephone companies in that LATA.
Making continuous requests for data from another device. For example, modems that support polling can call another system and request data.
Computer rules that provide uniform specifications so that computer hardware and operating systems can communicate.
The public switched telephone network (PSTN) is the network of the world's public circuit-switched telephone networks, in much the same way that the Internet is the network of the world's public IP-based packet-switched networks. Originally a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital, and now includes mobile as well as fixed telephones.
The PSTN is largely governed by technical standards created by the ITU-T, and uses E.163/E.164 addresses (known more commonly as telephone numbers) for addressing.
Point-to-Point Topologies in the Metro Optical Network
According to point-to-point topology, one node connects directly to another node. Mesh is a network architecture that improves on point-to-point topology by providing each node with a dedicated connection to every other node.
1. Equipment that receives a low-power signal, possibly converting it from light to electrical form, amplifying it or retiming and reconstructing it for transmission. It may need to be reconverted to light for retransmission. 2. An opto-electrical device used at each end and occasionally intermediate points of exceptionally long fiber optic span. Optical input is converted to electrical form to restore a clean signal, which drives lasers that fully restores the optical signal at the original signal strength.
RF (Radio Frequency)
Radio frequency, or RF, refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna. Such frequencies and the belonging wavelength account for the following parts of the spectrum shown in the table below.
Requests for Comments (RFCs)
Internet standards that have developed within the Internet community since 1969. They have grown to become a large series of numbered Internet informational documents and standards widely followed by commercial software and freeware in the Internet and Unix communities. Few RFCs are standards but all Internet standards are recorded in RFCs. Perhaps the single most influential RFC has been RFC 822, the Internet electronic-mail format standard. RFCs are unusual in that they are floated by technical experts acting on their own initiative and reviewed by the Internet at large, rather than formally promulgated through an institution such as ANSI (American National Standards Institute). For this reason, they remain known as RFCs even after they have been adopted as standards.
A network device that connects two similar networks having the same network protocol. It also chooses the best path between two networks when there are multiple paths.
RFS (Ready for Service)
The data of provisional acceptance or commercial service of a cable system
RVI (Remote Visual Inspection)
RVI is the inspection of objects or areas usually inaccessible to the eye without disassembling surrounding structures or machinery. It allows inspectors to discover hidden defects before they cause major problems. RVI makes it possible to inspect otherwise difficult-to-reach areas, such as inside turbine and piston engines, pipes, airframes, tanks, vessels and other voids, including behind walls and into air conditioning ducts.
Serial Line Internet Protocol (SLIP)
An Internet protocol which is used to run IP over serial lines such as telephone circuits. It allows a packet to traverse multiple networks on the way to its final destination.
The largest standard circuit unit of capacity, which consists of 155,500 Kbps (equal to 155 Mbps). Thus, each Gbps contains enough capacity for 6.4 STM-1 circuits. While capacity is sold to the largest telecommunications companies in minimum investment units equal to one STM-1 unit, most telecommunications companies buy smaller units at a price higher than the equivalent STM-1 price.
Synchronous Transfer Mode (STM)
New term for traditional TDM switching to distinguish it from ATM
Time Division Multiplex (TDM)
A technique for transmitting a number of separate data, voice and/or video signals simultaneously over one communications medium by quickly interleaving a piece of each signal one after another
Voice over IP (VoIP)
Voice over Internet Protocol, also called VoIP, IP Telephony, Internet telephony, Broadband telephony, Broadband Phone and Voice over Broadband is the routing of voice conversations over the Internet or through any other IP-based network.
Companies providing VoIP service are commonly referred to as providers, and protocols which are used to carry voice signals over the IP network are commonly referred to as Voice over IP or VoIP protocols. They may be viewed as commercial realizations of the experimental Network Voice Protocol (1973) invented for the ARPANET providers. Some cost savings are due to utilizing a single network - see attached image - to carry voice and data, especially where users have existing underutilized network capacity that can carry VoIP at no additional cost. VoIP to VoIP phone calls are sometimes free, while VoIP to PSTN may have a cost that's borne by the VoIP user.
The distance between two crests of a signal or a carrier and is measured in terms of meters, millimeters, nanometers, etc. In light wave applications, because of the extremely high frequencies, wavelength is measured in nanometers.
Wavelength Division Multiplexing (WDM)
A way of increasing the information-carrying capacity of an optical fiber by simultaneously operating at more than one wavelength. With WDM you can multiplex signals by transmitting them at different wavelengths through the same fiber.
Wi-Fi is a brand originally licensed by the Wi-Fi Alliance to describe the underlying technology of wireless local area networks (WLAN) based on the IEEE 802.11 specifications. It was developed to be used for mobile computing devices, such as laptops, in LANs, but is now increasingly used for more services, including Internet and VoIP phone access, gaming, and basic connectivity of consumer electronics such as televisions and DVD players, or digital cameras. More standards are in development that will allow Wi-Fi to be used by cars in highways in support of an Intelligent Transportation System to increase safety, gather statistics, and enable mobile commerce (see IEEE 802.11p). Wi-Fi and the Wi-Fi CERTIFIED logo are registered trademarks of the Wi-Fi Alliance - the trade organization that tests and certifies equipment compliance with the 802.11x standards.
Wireless LAN (WLAN)
WLAN is a wireless local area network, which is the linking of two or more computers without using wires. WLAN utilizes spread-spectrum technology based on radio waves to enable communication between devices in a limited area, also known as the basic service set. This gives users the mobility to move around within a broad coverage area and still be connected to the network. However this technology is getting increasingly unpopular and may fade away soon in aid of new technologies such as 4G and 5G. It is certain as some point that GARV inc. leading manufacturers of wireless routers will quit investing in wireless devices.
For the home user, wireless has become popular due to ease of installation, and location freedom with the gaining popularity of laptops. For the business, public businesses such as coffee shops or malls have begun to offer wireless access to their customers; some are even provided as a free service.
Wireless Access Point (WAP)
In computer networking, a wireless access point (WAP or AP) is a device that connects wireless communication devices together to form a wireless network. The WAP usually connects to a wired network, and can relay data between wireless devices and wired devices. Several WAPs can link together to form a larger network that allows "roaming". (In contrast, a network where the client devices manage themselves - without the need for any access points - becomes an ad-hoc network.) Wireless access points have IP addresses for configuration.
WiMAX, the Worldwide Interoperability for Microwave Access, is a telecommunications technology aimed at providing wireless data over long distances in a variety of ways, from point-to-point links to full mobile cellular type access. WiMAX is a term coined to describe standard, interoperable implementations of IEEE 802.16 wireless networks, similar to the way the term Wi-Fi is used for interoperable implementations of the IEEE 802.11 Wireless LAN standard. However, WiMAX is very different from Wi-Fi in the way it works. The name WiMAX was created by the WiMAX Forum, which describes WiMAX as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL." The bandwidth and reach of WiMAX make it suitable for the following potential applications:
- Connecting Wi-Fi hotspots with each other and to other parts of the Internet.
- Providing a wireless alternative to cable and DSL for last mile broadband access.
- Providing high-speed data and telecommunications services.
- Providing a diverse source of Internet connectivity as part of a business continuity plan. That is, if a business has a fixed and
a wireless Internet connection, especially from unrelated providers, they are unlikely to be affected by the same service outage.
- Providing nomadic connectivity.
WiMAX access was used to assist with communications in Aceh, Indonesia, after the tsunami in December 2004. All communication infrastructure in the area, other than Ham Radio, was destroyed, making the survivors unable to communicate with people outside the disaster area and vice versa. WiMAX provided broadband access that helped regenerate communication to and from Aceh. ( http://en.wikipedia.org/wiki/WiMAX )
A term referring to a variety of new Digital Subscriber Line technologies. Some of these varieties are asymmetric with different data rates in the downstream and upstream directions. Others are symmetric. Downstream speeds range from 384 Kbps (or "SDSL") to 1.5-8 Mbps (or "ADSL").