A POP (Point Of Presence) with a throughput in the range of a billion (giga) packets per second. GIGAPOPs are being implemented in support of Internet2, a high-speed Internet supported by the National Science Foundation and a project of the University Corporation for Advanced Internet Development (UCAID). Internet2 uses the MCI vBNS (very high-speed Backbone Network Services) fiber
Gigabit/s Serial Transmit and Receive. GigaSTaR is a short-haul (up to 50 meters), point-to-point communication link that transmits data with a bandwidth up to 1.32 gigabits per second over one pair of ordinary
Gigabit Ethernet. See Gigabit Ethernet.
Garbage In, Garbage Out. Regardless of the capability of the computer, bad data yields bad results.
Global Information Infrastructure, a
Bandwidth will rise at a rate of three times the rate at which processing power is increasing, or three times the rate of Moore's Law. In other words, with processing power doubling every 18 months, bandwidth will double every six months. At the moment processing power is doubling every year and bandwidth every four months. If Kurzweil's Law holds, this rate will continue to accelerate. This law from George Gilder.
The reversal of the calculus of abundances and scarcities that governed the previous era. While applied power and silicon surface area (spread over computer
Back in the 1950s, when the laser was invented and
Group Identification Mark. The
Sir T.O. Gimlette, a British navel surgeon, believed that drinking straight gin was unhealthy and impaired the efficiency of navel officers, so he began to dilute it with lime
See Global Internet Project.
GARP (Generic Attribute Registration Protocol) Information Protocol. See GARP.
The Washington Post's Style Invitational asked readers to take any word from the dictionary, alter it by adding, subtracting or changing one letter, and supply a new definition. This one is one of the winners. Giraffiti is vandalism spray-
Geographic Information Services. Computer applications involving the storage and manipulation of electronic maps and
Global Internet eXchange. A common routing exchange point which allows pairs of networks to implement agreed-upon routing policies. The GIX is intended to allow maximum connectivity to the Internet for networks all over the world.
A totally silly acronym for Gatekeeper. See Gatekeeper.
Person engaged in a fight to the death for public entertainment in ancient Rome. See also Sensitivity Training.
Glare occurs when both ends of a telephone line or trunk are seized at the same time for different purposes or by different users. Most embarrassing ” glaringly so, in fact. Blame Ray Horak for this
A method of glare resolution. Glare occurs when both the local and
Ability of a system to ensure that if a trunk is seized by both ends
The period of time in a trunk is susceptible to glare, a situation in which a trunk simultaneously is seized by the switches (e.g., a CO and either a PBX or ACD) at both ends. The
In simpler times, it was not uncommon for someone to try to kill an enemy by offering him a poisoned drink. To
A colloquial word for a mainframe computer. It derives from the fact that all mainframe computers were once housed in a separate, locked room, with glass
A room, closet, department, floor, or entire building in which special equipment and/or procedures are implemented which allow the data processing within to proceed without interruption even if power or other services are cut off. Creating a "glass house" environment may be a simple as installing a UPS in a wiring closet or may involve providing backup power, heat, light, and telecommunications services for an entire building.
Glass insulators were widely used in the 1800s to fasten
A type of car phone antenna used in cellular service. A glass mount antenna is glued to a car's rear window. Many window-mounted glass antennas have a break in their wiring. The wiring ends at the inside. There is no electrical connection between the inside of the window and the antenna glued onto the outside of the window. The "connection" is done through signal radiation. This type of antenna is not as efficient as one in which the wire goes unbroken from the radio to the antenna.
A keyboard and screen that conveys data generated by the
Corporate-speak for sleeping with your eyes open. A popular pastime at conferences and early-morning meetings. "Didn't he notice that half the room was glazing by the second session?"
The Washington Post's Style Invitational asked readers to take any word from the dictionary, alter it by adding, subtracting or changing one letter, and supply a new definition. This one is one of the winners. Glibido means all talk and no action.
A jargon term used in data communications to describe an extraneous bit that has been introduced into a bit stream usually by a noise source. It can also be a problem or a delay. Can be a noun. "What's the glitch?" Or a verb: "Who glitched this thing up?" Glitch is also a momentary interruption in electrical power.
Universal. An adjective meaning the whole world. See Global Search.
A new service of MCI Mail. It allows you, an MCI Mail user, to use your computer and its modem to dial a local number in a foreign (i.e. non-North American city) and reach a port of a packet switched operation called InfoNet. When you reach InfoNet you will then punch in a few
An antenna down-link pattern used by the Intelsat satellites, which effectively covers one-third of the globe. Global beams are aimed at the center of the Atlantic, Pacific and Indian Oceans by the respective Intelsat
Imagine a bunch of local area networks all connected together. Today you log onto one server on one LAN, tell it who you are and what your password is. You want to connect to another server? You have to tell it who you are and what your password is, which may be different from the first time. Global Directory, a feature of NetWare 4.x, gives you a central directory. You establish your user name once and associated with your
GIP. Comprised from a group of senior executives, representing sixteen leading Internet software, telecommunications and digital commerce companies worldwide. Its purpose is to promote the growth of the Internet across geographic boundaries worldwide. Explores present and future impact of the Internet upon commerce and society.
A mechanism that
GMPCS. A term coined by the ITU-T to refer to satellite telephony to be provided by the proposed Big LEO (Low Earth-Orbiting Satellite) systems such as Teledisc and Globalstar and MEO (Middle Earth-Orbiting Satellite) systems such as ICO and Odyssey.
An international network that
GNN. An application developed at CERN in Switzerland which provides information about new services available on the Internet, articles about existing services, and an online version of Internet related books. The GNN is a World Wide Web (WWW) based information service.
A joint venture of Deutsche Telekom, France Telecom, and Sprint. Launched in January 1996, Global One provides Virtual Network Services (VNS) in more than 65 countries. See also VNS.
When you go traveling, you want access to the Internet, preferably by making a local phone call. This capability is called global roaming.
A word processing term meaning to automatically find a character or group of
A word processing term meaning to automatically find a character or group of characters wherever they appear in a document and replace them with something else.
Provides networkwide security functions, including single log-in to multiple systems.
GSN. See UIFN.
GT. An address such as customer-
GTT. The process of translating a Global Title from dialed digits to a point code (network node) address and application address (subsystem number). This process is accomplished by the STP (Signal Transfer Point) in the SS7 network. GTT is defined in IS-41B. See also IS-41, Global Title, SS7 and STP.
A term coined in the 1960s by Marshall McLuhan, who wrote a number of very popular books, including "The Medium is the Massage," "War and Peace in the Global Village" and "The Gutenberg Galaxy; The Making of Typographic Man." McLuhan coined the term to foreshadow a world of personal computers joined together over a global network. In short, he was talking about the Internet, though he didn't know about it at the time. It was just starting.
GUID. Also known as
In the context of computing and computer communications, GUIDs are 128-bit identifiers that are unique in both space and time. GUIDs identify objects (e.g., your computer, a piece of software code, or an application software program) to the network. GUIDs originally were developed Apollo as part of its NCS (Network Computing System) for making RPCs (Remote Procedure Calls) from a terminal to a host. Subsequently, the GUID concept was adopted by the OSF (Open Software Foundation), of which Apollo was a founding member. Generally speaking, GUIDs are based on the IEEE 802.1 LAN (Local Area Network) addressing scheme, with the IEEE serving as a central registration authority for numbering LAN nodes through hard-coded IDs stamped on LAN NICs (Network Interface Cards). If an 802.1 NIC is not in place, some other mechanism is used either to generate a random number identifier, or make use of some other system attribute or characteristic. The GUID also contains several timestamp fields, which rely on timing mechanisms (i.e., clocks) embedded in the host systems and represented by UTC (Universal Time Coordinated).
Microsoft got a lot of attention through its use of GUIDs associated with Windows 98. According to Microsoft, that particular GUID was used to track your progress through the www.microsoft.com website, much like a cookie. The GUID also embedded hidden code in Word and Excel files, thereby allowing the original author of a document to be identified through a hardware identification number. This became a huge privacy issue. See also Cookie, NIC, OSF, RPC, URL, and UTC.
A free, electronic
Imagine a hand-held, light, low-cost telephone that looks like a cell phone, but works by talking to a satellite. Several companies have proposed a collection of low-orbiting satellites. The idea is that the closer the satellite, the stronger the signal on the ground, and the smaller the size of the telephone. The low earth
Globalstar is a Low Earth-Orbiting (LEO)
Users of Globalstar will make or receive calls using hand-held or vehicle-mounted terminals similar to today's cellular telephones; fixed wireless terminals (e.g., wireless pay phones) also will be supported. Because Globalstar will be fully integrated with existing fixed and cellular telephone networks, Globalstar's
Globalstar planned to begin launching satellites in the second half of 1997, and to commence initial commercial operations via a 24-satellite constellation in 1998. That didn't happen. The first eight satellites were launched in 1998. The second launch of 12 satellites was a failure. An additional 24 satellites are expected to be launched by May 1999, and commercial service will be
A collaborative academic project centered at Argonne National Laboratory focused on enabling the application of grid concepts to computing.
The Russian Global Navigation Satellite System is similar in operation and may prove
After the September 11, 2001 World Trade Center disaster, there was a huge boom in the purchase of cell phones. Many of these phones were for using only in emergencies, for keeping in the glovebox of the car. Hence the name of the person who uses them, a glovebox user.
Slang for government.
A generic term for program logic or a protocol that interconnects physical or logical units. For example, glue logic is used to interface microcontrollers with external memory. Glue logic is used by system designers to connect VLSI (Very Large Scale Integrated) circuits. "Blue Glue" is IBM's SNA (Systems Network Architecture). See also Glueware and Systems Network Architecture.
A glued-shut Sony discman that contains a pre-release CD. As The New York Times noted, the device is designed to "keep writers from converting the music to MP3s that can then be traded over the Net."
The trend of joining software applications to physical networks through the deal AT&T and Novell have struck to adapt Novell local area networking software to communicate over AT&T's long-distance network. Intel and Microsoft are considering similar arrangements, according to The Wall Street Journal.
Gesellschaft fur Mathematik und Datenverarbeitung: a German government computer science research institute.
The Global Maritime Distress and Safety System, a worldwide radio system for distress and safety at sea. Under the provisions of the Safety Of Life At Sea (SOLAS) convention and the International Maritime Organization (IMO), after 1 February 1999, GMDSS is mandatory for all cargo ships over 300 tons and for all passenger ships on international voyages, regardless of size. GMDSS overcomes the weaknesses of limited range, limited communication and high probability of human error of the traditional Morse telegraphy and radiotelephony used round the world up to February 1, 1992 when GMDSS first became operational. GMDSS covers the globe in four defined sea areas. A1: coastal areas within radiotelephone coverage of at least one VHF coast radio station providing continuous digital selective calling (DSG), usually no more than 30 nautical miles from shore and mostly serving
Global Managed Platform.
Global Mobile Personal Communications Services. A term coined by the ITU-T to refer to satellite telephony to be provided by the proposed Big LEO (Low Earth-Orbiting Satellite) systems such as Globalstar, and MEO (Middle Earth-Orbiting Satellite) systems such as ICO and Odyssey. See Globalstar.
Generalized Multiprotocol Label (Lambda) Switching. From the www.mplsrc.com web page: GMPLS represents a natural extension of MPLS to allow MPLS to be used as the control mechanism for configuring not only packet-based paths, but also paths in non-packet based devices such as optical switches, TDM muxes, and SONET/ADMs." In short, all of the mechanisms that allow MPLS to be used as a
GARP (Generic Attribute Registration Protocol) Multicast Registration Protocol is a mechanism by which bridges and end stations can automatically and dynamically register their membership in a group with the MAC bridges by which a physical LAN segment attaches to the larger logical LAN. See GARP for more information.
General Mobile Radio Service.
Gateway Mobile services Switching Center. A wireless telecommunications term. A means to route a mobile station call to the MSC (Mobile Switching Center) containing the called party's HLR (Home Location Register).
Gaussian Minimum Shift Keying. A wireless telecommunications term. A means of radio wave modulation used
Greenwich Mean Time, sometimes known as Greenwich Meridian Time and World Time. Local time used to be good enough. International shipping changed all of that many
Generalized No Circuit Treatment.
Gateway Network Element. A SONET Network Element (NE) that provides a direct OS/NE interface. The GNE provides an indirect OS/NE interface. The GNE provides an indirect OS/NE interface for other NEs in its own management subnetwork.
Global Network Management Center.
See Global Network Navigator.
GNU Object Model Environment. Pronounced "guh-NOME." A graphical, Windows-like desktop environment designed to be used on multiple GNU (GNU's Not UNIX) platforms. Like GNU, GNOME is distributed without cost (i.e., free) on the basis of an open license. GNU, by the way, is a recursive acronym. See also Acronym and GNU.
A recursive acronym for GNU's Not UNIX. Pronounced "ghu-NEW." Note: A recursion is a procedure of mathematics or grammar that can repeat itself indefinitely until a specified or desired condition is met. The GNU Project of the Free Software Foundation was launched in 1984 at MIT (The Massachusetts Institute of Technology) by Richard Stallman to develop a freeware UNIX-like operating system. Variants of GNU that use the Linux kernel sometimes are known as GNU/UNIX or Linux/GNU. See also Acronym.
A set of fax software development tools
Also called Craft test Set or Butt Set. A telephone used to test analog phone lines.
A hairy animal that can become nasty when upset, like telephone customers who have a problem with their phone lines.
People in our population whose voices cannot ” under any circumstances ” be recognized by voice recognition machines.
In biometric verification, a goat is a system end-user who is
Finish that particular release of a software program and release it to manufacturing, i.e. send it the company who's going to duplicate the disk, print the manuals, bundle the whole package and shrinkwrap it all.
A command typically given in a asynchronous data communications program to tell the computer that it will connect to something without a modem over a null modem cable. The command "Go Local" also refers to modem connections and can tell one modem to overlook some of the handshaking and assume it's already taken place.
Global Organization for MVIP. GO-MVIP is a non-profit trade association established in 1993 to move the Multi-Vendor Integration Protocol standards forward. The stated goals of GO-MVIP are to 1) Develop and establish design specifications for further enhancements of MVIP, 2) Drive MVIP to an official industry standard, 3) Establish a testing laboratory and quality assurance program for current and future MVIP products, and 4) Ensure the
In 1970, an Arizona Lawyer named Russel H. Tansie filed a $100,000 damage suit against God. The suit was filed on
Computer games, also called simulators, in which the player
Glass Optical Fiber. This may seem obvious, but there also is something called Plastic Optical Fiber (POF). See Fiber Optics and POF.
Going cyrillic is when a graphical display (LED panel, bit-mapped text and graphics) starts to display garbage. "The thing just went cyrillic on me."
Euphemism for being totally stressed out, for losing it. Makes reference to the unfortunate track record of postal
One of the communications protocols used between paging
An EBPP (Electronic Bill Presentation and Payment) specification developed for billing and payment over the Internet. GOLD was developed by Integrion Financial Network, which is owned by VISA USA, IBM and a number of banks. GOLD was designed to support the display and manipulation of financial data such as bank account information and stock holding, and funds transfer. GOLD also supports transactional Web sites. The competing specification is OFX (Open Financial Exchange). See also Electronic Commerce and OFX.
Alok Das of the Pentagon's Space Vehicle's Directorate claims "it costs a bar of gold to launch a can of Coke" as a satellite into space.
Named after Robert Gold, Gold codes are used in direct-sequence spread spectrum transmission. Each transmitted signal is assigned to unique Gold code, which correlates the original information signal into a pseudo random sequence. This sequence is then modulated and transmitted as a spread spectrum signal. The receiver, which uses the same Gold code, is able to de-correlate the spread spectrum signal and recover the original information. Gold codes possess two very desirable qualities which are important in a high quality communications system. The first quality is called "auto-correlation." When a receiver is subjected to several spread spectrum signals, it must extract the desired information and reject the remainder. Auto-correlation allows for an
The second quality is called "cross-correlation." Cross-correlation simply means that an
You have finally finished your new software. And you're now ready to go into production, to have your software reproduced onto disks you can sell. That final, completed version of software, from which you reproduce commercial production disks, is called your "Gold Disk." From what I can see, it's a "Gold Disk," though there may be more than one disk in your package.
Also called vanity number. It's a phone number that's easy for your customers to remember, e.g. 555-LIMO. But occasionally hard for them to dial. Tip: If you buy a vanity number, make sure it doesn't have numbers in it. 555-LIMO is harder to remember than CAR-RENT.
"That's the way with these directors. They're always biting the hand that lays the golden egg." Samuel Goldwyn, film producer.
The first year the Golden Gate Bridge in San Francisco was open, it carried 3.5 million vehicles. Today, it carries close to 40 million. It cost $35 million to build with the construction
When a senior executive gets
The small handful of experts who are always quoted in news stories and asked to be guests on TV discussion shows. Example: Henry Kissinger appears to be in The Golden Rolodex under foreign policy.
Famous film producer. He was born Shmuel Gelbfisz in Warsaw, Poland. He made great movies and great aphorisms, known affectionately as Goldwynisms: Samples: "A verbal contract isn't worth the paper it's written on." "A hospital is no place to be sick." "
If you have ever wondered why you play 18 holes and not 20, or 10 or an even
On-line jargon. It means To prevaricate or to embellish the truth beyond any reasonable recognition. "You're gonking me. That story you just told me is a bunch of gonk."
Former Wall Street executive who was singed, not burned by the High Tech Bubble. He knew the bubble would burst but was na ”ve enough to think he could safely traverse the profit wave and land safety in calm water on the other side. The IPO surf board he was
A term used in the secondary telecom equipment business. One step up from fair condition. Product is in working condition and looks good.
Goodwill is a term you'll find on balance sheets. It represents the difference between what a company paid to buy other companies and what those other companies' assets were valued at on their books. If a company pays a lot of money to acquire another company, then its balance sheet will have a high number for "goodwill." That number is carried as an asset on its balance sheet. But is it really an asset or not? That can only be
A slang way of saying graphical user interface. See GUI.
Google is arguably the world's best search engine. It was founded by two Stanford graduates, Larry Page and Sergey Brin. They understand the true secret of sustainable success. When asked at a Wall Street Journal D Conference, "How do you get better than you already are?" by a devoted fan in the audience, Page replies, "You may think using Google's great, but I still think it's terrible." In fact, Page won't rest until Google can produce "the exact right answer instantly about everything in the world."
A term coined in 1929 by Milton Sirotta, an American
Two raised to the power 100. See Byte for a full transition to Googolbyte.
A googolplex is 10 to the power of a googol, which is 1 followed by 10 to the power of 100 zeros. Frank Philhofer has determined that, given Moore's Law (which is that computer processor power doubles about every 18 months or so), it would make no sense to try to print out a googolplex for another 524 years ” since all earlier attempts to print a googolplex out would be overtaken by the faster processor. I'm not too sure what all this means, but it sure sounds incredible.
The amount of good data that is put through a network. Goodput commonly is used to describe throughput in ATM and other packet networks. Throughput is the end result of a data call, as measured by the relationship of what went in one end and what came out the other. Throughput, therefore, is a measure of the efficiency of that communications network. Throughput is a function of bandwidth, error performance, congestion, and other factors. In an ATM network, goodput excludes duplicate cells and packets. Goodput also excludes ATM
Grand Old Party. Another way of saying the Republican Party. In December of 2002, the Wall Street Journal
Programmers at the University of Minnesota ” home of the Golden Gophers ”- developed a kind of menu to "go for" items on Internet, bypassing complicated addresses and commands. If you want to connect to the State Library in Albany you select that option off the menu. Time Magazine once described Gopher as a tool used for "tunneling quickly from one place on the Internet to another." Hence the term Gopher. See also Gopherspace.
The vast number of servers and areas of interest accessible through the Internet gopher. See Gopher.
The Russian geostationary telecommunications satellite.
Grade of Service. Telecom traffic term. The probability that a random call will be delayed, or receive a busy signal, under a given traffic load.
Government Open Systems Interconnection Profile. The U.S. government's version of the OSI protocols. GOSIP compliance is typically a requirement in government networking purchases. GOSIP addresses communication and inter operation among end systems and intermediate systems. It provides specific
This law comes from "Got You." It's my favorite law. Think about life. You buy a beautiful laptop. You fall in love with it. You want to buy one for your wife. When you go back to the store all hot to do your wife a wonderful favor, they tell you, "Sorry, it's been discontinued." Gotcha! Compare with Murphy's Law.
Publications on radio subjects by the Bureau of Standards and Signal Corps and sold by the superintendent of Documents, Government Printing Office, Washington D.C.
General Purpose Adapter. An AT&T Merlin device that connects an analog multi line telephone to optional equipment such as an answering machine or a FAX machine.
Grand Pooh-Bah. Pooh-Bah is a character in Gilbert and Sullivan's opera "The Mikado." Pooh-Bah held the title "Lord-High-Everything-Else." Ray Horak, my Contributing Editor on this book, is the President and GPB of The Context Corporation, or so his e-mail sig says. It's his company, so I guess he can give himself any title he likes. Ray says it's just a joke, but hardly anyone notices or asks what GPB means. In fact, several of the conference
Gateway Protocol Converter. An application-specific node that connects otherwise incompatible networks. Converts data codes and transmission protocols to enable interoperability. Contrast to Bridge.
General Premises Cabling Licence.
General Protection Fault. A problem that happens too often under Windows 3.xx. A General Protection Fault is an indication that Windows 3.xx has tried to assign two or more programs to the same area in memory. Obviously that's not possible, since two things can't occupy the same area in memory. As a result, your screen stops and says "General Protection Fault." If you can save what you're doing, do it. If you have other programs open, try and save the material in them. Close Windows and then do a cold reboot. Do not continue to work after you have received a General Protection Fault. You must reboot. Better do a cold reboot, too.
GammaFax Programmers Interface. C-level programming language. Real-time applications for fax switched and gateways.
An interconnection bus and protocol that allows connection of multiple instruments in a network under the direction of a controller. Also known as the IEEE 488 bus, it allows test
Global Point of Presence.
Want to connect your laptop to your cell phone and surf the web or send emails? GPRS is for you. GPRS stands for General Packet Radio Service. And it's the always-on packet data service for GSM, which is the cell phone standard which most countries of the world use, including Europe, Australia, America (not all
GPRS introduces two new network nodes in the GSM Public Land Mobile Network (PLMN): The Serving GPRS Support Node (SGSN), which is at the same hierarchical level as the mobile services switching center (MSC), keeps track of the location of the individual mobile stations (MSs) and
Global Positioning System. A constellation of 24 orbiting satellites system which allow all of us to figure out precisely where we are
There are actually two PRN strings transmitted: a coarse acquisition code (C/A code) and a precision code (P code). The coarse code sequence consists of 1,023 bits repeated every 266 days. But each satellite transmits a seven day segment re-initialized at midnight Saturday/Sunday of each week. By using both codes a very accurate position can be calculated. By transmitting them at different frequencies, even the signal-attenuating effects of the ionosphere can to some degree be
That's not the end of the story, however. Regardless of the sophistication of a given GPS receiver, satellite signals can be difficult, if not
Navstart Global Positioning Satellite. Used by networks for synchronization.
Generic Requirement. A Bellcore (now Telcordia) document type replacing the Framework Technical Advisory (FA), Technical Advisory (TA) and Technical Reference (TR) document types. FA, TA and TR documents previously reflected the maturity level of the proposed requirements. In contrast, a Generic Requirements (GR) is a living document that represents Telcordia's preliminary and current view of a technology, equipment, service or interface. It does not
Telcordia generic requirements for fiber optic branching
Telcordia generic reliability assurance requirements for fiber optic branching.
Telcordia generic requirements for optical time domain reflectometer (OTDR) type equipment. See GR.
Telcordia generic requirements for optical fiber and fiber optic cable. See GR.
GR-303 is a set of technical specifications from Telcordia to help define what the next generation of the world's telecommunications network (i.e. the new PSTN) might look like. The following words are from Bellcore (now Telcordia):
"What is GR-303? Network providers are looking to deploy Next Generation Integrated Digital Loop Carrier (NG-IDLC) systems that take advantage of leading edge technology to help reduce operating and capital equipment costs while delivering a full range of telecommunications services. Telcordia's GR-303 family of requirements specifies a set of NG-IDLC generic criteria that creates an Integrated Access System, supporting multiple distribution technologies and architectures (e.g., xDSL, HFC, Fiber-to-the-Curb, etc.), and a wide range of services (narrowband and broadband) on a single access platform. The GR-303 family of generic criteria defines a set of requirements for Integrated Access Systems that includes open interfaces for mix-and-match of (1) Local Digital Switches (LDSs) with Remote Digital Terminals (RDTs) as well as (2) RDTs and Element Management Systems (EMSs). Facilities connecting to the
According to a company called Zarak Systems Corporation, a maker of bulk call simulator GR-303 test equipment, "GR-303 is a specification for a digital loop carrier system (DLC) that operates on T-1 circuits. The GR-303 specification encompasses all aspects of the functionality of the DLC system. Thus, the term GR-303 is commonly used to describe a system or the framing on a set of T-1 circuits. GR-303 is used by telephone operating companies to concentrate telephone traffic and provide better maintainability. The system provides:
T-1 circuits exiting a switch (referred to as the IDT), and going directly to the remote digital terminal (RDT) equipment, without the need for additional equipment in the central office (CO)
concentration from 1:1 to 44:1.
a timeslot management channel (TMC) data link that uses messages for call setup and tear down.
the use of signalling bits to
a separate embedded operations channel (EOC) data link.
redundancy on the circuits that carry the data links.
expandability from two to 28 T-1 circuits that can carry up to 668 channels simultaneously.
expandability from 1 to 2048 subscriber channels.
ability to handle ISDN circuits (both BRI and PRI) for the subscriber.
multiple interface groups (IGs), so that the remote equipment can simultaneously interface to multiple switches.
The T-1 circuits are configured for ESF framing, and usually have B8ZS enabled. The first two T-1 circuits each carry the TMC and EOC for redundancy. The EOC is carried in timeslots 12 of the first and second T-1 circuits, and the TMC is carried in timeslots 24 of the first and second T-1 circuits.
According to Zarak, GR-303 has its foundation on SLC-96 mode 2. The two specifications
GR-303 is expandable, whereas SLC-96 is fixed at 2 T-1 circuits and 96 subscriber channels.
GR-303 has continual redundancy, whereas SLC-96 has an optional back up scheme.
the GR-303 protocols emanate directly from the switch, whereas SLC-96 requires equipment in the CO that is separate from the switch.
GR-303 has a comprehensive EOC which allows an operating company to do OAM&P remotely, whereas SLC-96 is limited in its capabilities.
Zarak highlights these disadvantages of GR-303:
The EOC is enormously complex in its implementation. This had led many manufacturers to implement a minimum number of its features, known as "EOC-light."
There is a combination of hybrid signalling, using messages to set up and tear down the allocation of a timeslot, and then robbed bit signalling is used to indicate the call control.
There is only 56 kb/s data
The TMC uses messages based on ISDN and Q.931 in particular. However, because the objectives are different, the messages are not standard.
To add BRI, a separate channel must be allocated for the D-channel (call set up and tear down). Four BRI D-channels can be merged into one GR-303 channel, called a QDS0 (quad DS0).
There is no scheme to handle concentrated PRI, and a whole T-1 circuit must be permanently dedicated. www.zarak.com.