802.11
802.11 is a family of specifications for wireless local area networks (WLANs) developed by a working group of the Institute of Electrical and Electronics Engineers (IEEE). There are currently four specifications in the family: 802.11, 802.11a, 802.11b, and 802.11g. All four use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing.
ASP
Application Service Provider
ATM (Asynchronous Transfer Mode)
A high speed networking technology that is connection oriented. Information is divided into cells of fixed-length. The cells are switched, multiplexed and delivered to their destination. Data streams are sent independent to each other (i.e. not driven by a common network clock).
Attenuation
The loss of strength (power) that a signal encounters as it propagates through a medium.
Bandwidth
The amount of data that can be transmitted over a given time period.
BIR
Burst Information Rate, a term borrowed from Frame Relay, defines the maximum throughput of the service.
Bit
A contraction of the "binary digit". A bit is the smallest possible unit of storage of computer information and can be one of two values. These values are typically represented by 0 and 1, low and high, or on and off. There are 8 bits in a byte.
bps
bits-per-second. A measure of data transmission, such as that handled by a modem.
Broadband
A term that describes high data transmission rates (typically in excess of 6 Mbps).
Byte
In most computer systems, a byte is a unit of data that is eight bit digits long. A byte is the unit most computers use to represent a character such as a letter, number, or typographic symbol (for example, "g", "5", or "?").
Co-ax (Co-axial Cable)
A cable consisting of two conductors: one conductor is tubular and surrounds the other conductor. The outer conductor is usually made of fine metal strands woven together. The two conductors are separated by a dielectric (non conductive material) that helps determine the signal transmission characteristics.
CIR
Committed Information Rate, a term borrowed from Frame Relay, defines the guaranteed throughput of the service.
Cross-talk
A term that describes the undesirable migration of communication signals between adjacent channels or conductor pairs.
Data Transfer
Data transfer is the amount of digital data that is moved from one place to another in a calendar month as measured by MRTG on the customer's port connection.
Dedicated access
A direct connection between a terminal and a service, network or computer dedicated to the specific use of a particular customer.
Dial access (roaming)
Ability to access the Internet through a dial up connection.
Dial up
The use of a rotary-dial or Touch-ToneTM telephone to initiate a station-to-station telephone call.
DS-1
Digital Signal Level 1, 1.544 Mbps.
DS-3
Digital Signal Level 3, 44.736 Mbps.
DSL (Digital Subscriber Line)
Most commonly used in its asymmetric form, "xDSL". This technology uses high frequency signals on ordinary copper pairs to provide high speed data communication.
Dual Homing
Dual homing ensures that you stay connected to the World Wide Web even if one of our Tier 1 providers' networks goes down or if their national backbone feeds into the network are interrupted, Atria's system will automatically move its entire feed to the other provider through BGP (Border Gateway Protocol).
Duplex
In telecommunication, duplex communication means that both ends of the communication can send and receive signals at the same time. Full-duplex communication is the same thing. Half-duplex is also bidirectional communication but signals can only flow in one direction at a time. Simplex communication means that communication can only flow in one direction and never flow back the other way.
DWDM
Dense Wavelength Division Multiplexing
e-mail address
Electronic identification that enables users to send and receive electronic mail.
EMI (Electromagnetic Interference)
Involves the undesired coupling of stray electromagnetic waves onto a communication cable. These stray waves interfere with the reception of the valid signal at the receiving end.
Firewall
A system designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially Intranets. All messages entering or leaving the Intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria.
A firewall is considered a first line of defense in protecting private information. For greater security, data can be encrypted. There are several types of firewall techniques:
Packet filter: Looks at each packet entering or leaving the network and accepts or rejects it based on user-defined rules. Packet filtering is fairly effective and transparent to users, but it is difficult to configure. In addition, it is susceptible to IP spoofing.
Application gateway: Applies security mechanisms to specific applications,such as FTP and Telnet servers. This is very effective, but can impose performance degradation.
Circuit-level gateway: Applies security mechanisms when a TCPTM or UDP connection is established. Once the connection has been made, packets can flow between the hosts without further checking.
Proxy server: Intercepts all messages entering and leaving the network. The proxy server effectively hides the true network addresses.
Filter
A device that prevents noise interference and is installed between a telephone and its wall jack.
Fractional T1
A fraction or portion of the 24 channels @ 64kbps to produce a 1.544 Mbps circuit.
Gateway
This is a device that converts different protocols; a network interconnectivity device that translates communications protocols. In networking, it is a combination of hardware and software that links two different types of networks. Gateways between e-mail systems, for example, allow users on different e-mail systems to exchange messages.
Gateway Address
A gateway address is the IP address of a network point that acts as an entrance to another network. For example, in a corporate network, a proxy server acts as a gateway between the internal network and the Internet.
Gbps
Giga bit per second or 1,000 Mbps
Hub
A common connection point for all devices connected to a star network. A passive hub simply serves as a conduit for the data, enabling it to go from one device to another. So called intelligent hubs include additional features that enable them to act as a bridge, transferring data between different types of networks. Some hubs are full-fledged computers that also act as network servers.
Inherently Scalable
Inherently scalable refers to the fibre-optic infrastructure that Atria uses to connect to all its customers. The same single mode fibre-optics that Atria uses to connect to an Enterprise Internet Service (2 Mbps) customer is the same used in its Gb (1,000 Mbps) connections.
Internet
A wide-area network that connects tens of millions of computers worldwide. Originally implemented by the U.S. Defence Department, Internet is now administered by an independent organization.
Members include: government agencies, educational institutions and large corporations.
IP
Internet Protocol. A layer three protocol that contains addressing information and some control information that allows packets to be routed.
ISDN
Digital Subscriber Line. 128 kbps telephone line service that works up to 18,000 feet.
kbps
Kilobits-per-second (thousands of bits-per-second). A measure of data transmission, such as that handled by a modem.
Layer
The reference model for communication programs, Open System Interconnection (OSI) is a layered set of protocols in which two multilayered programs, one at either end of a communications exchange, use an identical set of layers. In the OSI model, each multilayer program contains seven layers, each reflecting a different function that has to be performed in order for program-to-program communication to take place between computers. TCP/IP is an example of a two-layer (TCP and IP) set of programs that provide transport and network address functions for Internet communication. A set of TCP/IP and other layered programs is sometimes referred to as a protocol stack.
Layer 2
Layer 2 refers to the Data Link layer of the commonly referenced multilayered communication model, Open Systems Interconnection (OSI). The Data Link layer is concerned with moving data across the physical links in the network. In a network, the switch is a device that redirects data messages at the layer 2 level, using the destination Media Access Control (MAC) address to determine where to direct the message.
Layer 3
Layer 3 refers to the Network layer of the commonly referenced multilayered communication model, Open Systems Interconnection (OSI). The Network layer is concerned with knowing the address of the neighbouring nodes in the network, selecting routes and quality of service, and recognizing and forwarding to the Transport layer incoming messages for local host domains. A router is a layer 3 device, although some newer switches also perform layer 3 functions. The Internet Protocol (IP) address is a layer 3 address.
Line
A communications channel. Also called a circuit, trunk or facility. It often refers to customer access to the public switched telephone network (e.g. residence line, individual business line).
LMDS
Local Multipoint Distribution System
Mbps
Megabits-per-second (millions of bits-per-second). A measure of data transmission, such as that handled by a modem.
Media Converter
A media converter is a device that converts the optical signal to an electrical Ethernet signal to be connected to a company's LAN.
Modem
Device that modulates and demodulates data usually transmitted over a regular telephone line.
Network
A series of points interconnected by telecommunications channels.
OC-3
155 Mbps connection associated with ATM or Packet over SONET link.
Port
The entrance or access point to a computer or multiplexer.
Proxy Server
A server that sits between a client application, such as a Web browser, and a real server. It intercepts all requests to the real server to see if it can fulfill the requests itself. If not, it forwards the request to the real server. Proxy servers can also be used to filter requests. For example, a company might use a proxy server to prevent its employees from accessing a specific set of Web sites.
PVC (Permanent Virtual Circuit)
A link established through an ATM network that provides a transmission path between two points. Software rather than hardware configuration is required to set up the link. This link is configured prior to the delivery request and remains intact between transmission sessions.
QAM
Quadrature Amplitude Modulation
QoS
QoS (Quality of Service) is the idea that transmission rates, error rates, and other characteristics can be measured, improved, and, to some extent, guaranteed in advance. QoS is of particular concern for the continuous transmission of IP telephony, high-bandwidth video and multimedia information and requires adherence to Ethernet protocols such as 802.1p. Transmitting this kind of content dependably is difficult in other networks using ordinary "best effort" protocols.
Router
A device that connects two LANs. Routers are similar to bridges, but provide additional functionality, such as the ability to filter messages and forward them to different places based on various criteria. The Internet uses routers extensively to forward packets from one host to another.
Session
In telecommunications, a session is a series of interactions between two communication end points that occur during the span of a single connection. Typically, one end point requests a connection with another specified end point and if that end point replies agreeing to the connection, the endpoints take turns exchanging commands and data ("talking to each other"). The session begins when the connection is established at both ends and terminates when the connection is ended.
Streaming
A method of delivering information (usually sound and/or video) over the Internet such that it can be played on a receiving computer at the same time it is being delivered.
Subnet
A portion of a network that shares a common address component. On TCP/IP networks, subnets are defined as all devices whose IP addresses have the same prefix. For example, all devices with IP
addresses that start with 100.100.100 would be part of the same subnet. Dividing a network into subnets is useful for both security and performance reasons. IP networks are divided using a subnet
mask.
Symmetric
In telecommunications, the term symmetric (also symmetrical) refers to any system in which data speed or quantity is the same in both directions, averaged over time.
T-1
24 voice channels @ 64kbps to produce a 1.544 Mbps circuit.
T-3
720 voice channels @ 64kbps to produce a 44.736 Mbps circuit.
Tbps
Tera bit per second or 1,000,000 Mbps
Telnet
A terminal emulation program for TCP/IP networks such as the Internet. The Telnet program runs on your computer and connects your PC to a server on the network. You can then enter commands through the Telnet program and they will be executed as if you were entering them directly on the server console. This enables you to control the server and communicate with other servers on the network. To start a Telnet session, you must log into a server by entering a valid username and
password. Telnet is the most common way to remotely control Web servers.
TLS
Transparent LAN Service are a sub-set of LAN extensions that use Ethernet-type protocols at the customer end.
VLAN or virtual LAN
Group of devices on one or more LANs that are configured (using management software) so that they can communicate as if they were attached to the same wire, when in fact they are located on a number of different LAN segments. Because VLANs are based on logical instead of physical connections, they are extremely flexible.
VoIP
Voice over Internet Protocol.
VPN
Virtual Private Network. An encrypted connection between private networks over a public network such as the internet.
WAN
Wide Area Network
Web Server
This is a computer that delivers (serves up) Web pages. Every Web server has an IP address and possibly a domain name. For example, if you enter the URL http://www.atrianetworks.com/ into your browser, a request is sent to the server with the domain name: atrianetworks.com. The server then fetches the page named Tools and sends it to your browser. Any computer can be turned into a Web server by installing server software and connecting it to the Internet. There are many Web server software
applications, including public domain software from NCSA and commercial packages from Microsoft, Netscape, and others. Atria Member Services does not provide support for Web servers.
