Glossary of Internet Terms - FAQs -Internet Reference

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SDSL - Symmetrical Digital Subscriber Line - A version of DSL where the upload speeds and download speeds are the same. HDSL plus POTS over a single telephone line. This name has not been adopted by a standards group but is being discussed by ETSI. It is important to distinguish, however, as SDSL operates over POTS and would be suitable for symmetric services to premises of individual customers.

Server - A computer that provides a specific kind of service to requests for information.  For example, servers host email which is downloaded by a user using a web browser or mail client like Eudora or Outlook.  Servers also host websites and other applications, such as e-commerce sites that can be used by the general public or privately on an internal network.

A single server can have several different applications running on it, thus providing many different services to a wide variety of users in various locations, or it can be used for one single application.

SMTP -- (Simple Mail Transfer Protocol) The main protocol used to send electronic mail from server to server on the Internet.

SOHO - Small Office Home Office - A smaller business, but one that may need a more robust or “always on” connection to the Internet.  In the case of a telecommuter working from home (as opposed to the “home office” in Indianapolis), the connection might need to be capable of connecting securely to the company’s network at the home office.

T1 - A T1 (also referred to as a leased line) transfers data between two points at up to 1.544 Mbps, with the same speed in each direction.  This “symmetrical” connection, unlike cable access, dial-up or DSL, is ideal for customers who need a high-speed Internet connection or who have many workstations or servers that need to be connected. T1s, or leased lines, can also be used as point-to-point circuits (PtP), connecting two locations (such as a branch office or a sales office with a factory)  A T1 is capable of downloading at speeds nearly 30 times faster than dial-up and provides upload speeds that are 50-60 times faster.  These circuits are extremely reliable and have the ability to be configured in a variety of ways.  Some T1s are used for VoIP or other voice applications and can also be set up for other technologies.  Some T1 connections are limited to transferring data at a fraction of their maximum speed.  These are referred to as “fracs.”

T3 - (also known as a DS-3) is a leased line connection that is capable of carrying data at 44,736,000 bits-per-second (44.7 Mbps). This is more than enough to do full-screen, full-motionvideo.  A T-3 line actually consists of 672 individual channels, each of which supports 64 kbps.  Also equivalent to 28 T1 lines.

TCP/IP - (Transmission Control Protocol/Internet Protocol) The primary protocols that allow the Internet to transfer data among the various networks that make up the Internet. IP protocol deals only with packets of data.  TCP enables two hosts to establish a connection and exchange streams of data.  TCP guarantees delivery of data and also guarantees that packets will be delivered in the same order in which they were sent. Originally designed for the UNIX operating system, TCP/IP capability is built into virtually every computer and device capable of connecting to the Internet.

TELCO – (Telephone Company)  A generic name for telephone companies throughout the world, including SBC in Chicago and other Regional Bell Operating Companies, Worldcom or Local Encumbent Carriers.

VDSL – (Very high bit-rate Digital Subscriber Line) – A twisted pair access connection, operating at data rates from 12.9 to 52.8 Mbps with corresponding maximum reach ranging from 4500 to 1000 feet of 24-gauge twisted pair.

VoIP - (Voice over Internet Protocol) - A category of hardware and software that enables people to use the Internet as the transmission medium for telephone calls.  Voice data is sent in packets using rather than by traditional POTS circuits. One advantage of VoIP is that the telephone calls over the Internet do not incur a surcharge beyond what the user is paying for Internet access, much in the same way that the user doesn't pay for sending individual e-mails over the Internet.

VoIP can also be used to carry voice traffic from a user to the PSTN. (This is one of Novacon's VoIP solutions) Traffic can be carried on each channel of a T-1 or DS-3 (1 call per channel) or all calls can be aggregated dynamically as packets on the circuit.  Calls are then transferred in a data center to the PSTN and their final destination.

There are a number of new Internet telephony applications available. Some are used with web browsers, while others are stand-alone products. VoIP also is referred to as Internet telephony or IP telephony.

VPN - (Virtual Private Network) These systems use encryption and other security systems to ensure that only authorized users have access to the network, especially if the Internet is used, and that the data cannot be intercepted.

WAN -- (Wide Area Network)  A network that covers an area larger than a single building or campus.  Sometimes a WAN is used to connect 2 or more locations across town, allowing both locations to share resources, such as Internet access or files on an internal server.  The connections between these locations are often leased lines, such as T1 or T3 lines.  In cases where locations in other states or countries are tied together, frame-relay circuits are often used.

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