Glossary-G
A Data Communication Historical Series
By Bob Pollard

HOME               INDEX

G.703/G.704:

ITU-T electrical and mechanical specifications for connections between telephone company equipment and DTE using BNC connectors and operating at E1 data rates.

G.711:

Describes the 64-kbps PCM voice coding technique: In G.711 encoded voice is already in the correct format for digital voice delivery in the PSTN or through a PBX(s); Described in the ITU-T standard in its G-series recommendations

G.723.1:

Describes a compression technique used to compress speech or audio signal components at a very low bit rate; part of the H.324 family of standards. This CODEC has two bit rates associated with it: 5.3 and 6.3 kbps. The higher bit rate is based on ML-MLQ technology and provides a somewhat higher quality of sound. The lower bit rate is based on CELP and provides system designers with additional flexibility. Described in the ITU-T standard in its G-series recommendations

G.726:

Describes ADPCM coding at 40, 32, 24, and 16 kbps: ADPCM-encoded voice can be interchanged between packet voice, PSTN, and PBX networks if the PBX networks are configured to support ADPCM. Described in the ITU-T standard in its G-series recommendations

G.728:

Describes a 16-kbps low-delay variation of CELP voice compression: CELP voice coding must be translated into public telephony format for delivery to or through a PSTN; described in the ITU-T standard in its G-series recommendations

G.729:

Describes CELP compression where voice is coded into 8-kbps streams. There are two variations of this standard (G.729 and G.729 Annex A) that differ mainly in computational complexity; both provide speech quality similar to 32-kbps ADPCM. Described in the ITU-T standard in its G-series recommendations

G.804:

The ITU-T framing standard that defines the mapping of ATM cells into the physical medium.

GAIN:

Refers to an increase of amplitude (power), usually specified as a deci-Bel (dB) level gain. Amplification is usually accomplished through the use of a repeater or some other form of amplifier.

GAIN HITS:

An expression that identifies any undesirable short signal surges (hits), which may or does create data errors

GAME PORT:

An input/output connector to which a user can attach a joy stick or other game device to the computer: It is typically a 15-pin socket on the back of a PC.

GANG PUNCHING:

High-speed parallel punching method: Reproduces fixed information from a master card into a series of detail cards.

GARBAGE:

A term used to describe faulty or corrupted data. Another term: ‘Garbage In, Garbage Out’, which is used to express “bad data into the system gives bad data out” during a processing function.

GATE:

A circuit that yields an output signal based on present or past input signals. See Boolean Algebra

GATEKEEPER:

1. The component of an H.323 conferencing system that performs call address resolution, admission control, and subnet bandwidth management.

2. Telecommunications: H.323 entity on a LAN that provides address translation and control access to the LAN for H.323 terminals and gateways. The gatekeeper can provide other services to the H.323 terminals and gateways, such as bandwidth management and locating gateways. A gatekeeper maintains a registry of devices in the multimedia network. The devices register with the gatekeeper at startup and request admission to a call from the gatekeeper.

GATEWAY:

   A device connected to multiple physical TCP/IP (Transmission Control Protocol/Internet Protocol) networks capable of routing or delivering IP (Internet Protocol) packets between them. A gateway translates between different transport protocols or data formats (example: IPX and IP) and is generally added to a network primarily for its translation ability.

   In the context of interoperating with Novell NetWare networks, a gateway acts as a bridge between the Server Message Block (SMB) protocol used by Windows networks and the NetWare Core Protocol (NCP) used by NetWare networks. A gateway is also called an IP router.

GATEWAY DISCOVERY PROTOCOL (GDP):

A Cisco protocol that allow host computers to dynamically detect the arrival of new routers and to detect router failures; based on UDP

GATEWAY HOST:

In SNA, a host node that contains a gateway SSCP

GATEWAY NCP:

Network Control Program (NCP) that connects two or more SNA networks and performs address translation to allow cross network session traffic

GATEWAY PROTOCOL CONVERTER:

An application-specific node that converts data codes and transmission protocols to ensure compatibility between incompatible networks; contrast with bridge.

GATEWAY SERVER:

A station on a local area network (LAN) that makes the connection to the host available to one or more network users; see Bridge or Link.

GATEWAY-TO-GATEWAY PROTOCOL GGP):

The protocol used by core gateways to exchange routing information. GGP implements a shortest path routing computation.

GAUSSIAN NOISE:

Refers to line noise, such as white noise or hiss

Gb:

Gigabit: 1,000,000,000 bits

GB:

Gigabyte: 1,000,000,000 bytes.

gbs:

Gigabits per second: 1,000,000,000 bits per sec

GBS:

Gigabytes per second: 1,000,000,000 bytes per sec

GCCS:

Global Command and Control System

GCRA:

Generic Cell Rate Algorithm: In ATM, an algorithm that defines conformance with respect to the traffic contract of the connection. For each cell arrival, the GCRA determines whether the cell conforms to the traffic contract.

GDP:

See Gateway Discovery Protocol

GENERAL SWITCHED TELEPHONE NETWORK (GSTN):

Same as public telephone network (PTN).

GENERAL TELEPHONE OPERATING COMPANY (GTOC):

An operating company owned by GTE.

GENERIC ROUTING ENCAPSULATION (GRE):

Tunneling protocol developed by Cisco that can encapsulate a wide variety of protocol packet types inside IP tunnels, creating a virtual point-to-point link to Cisco routers at remote points over an IP inter-network. By connecting multi-protocol sub-networks in a single-protocol backbone environment, IP tunneling using GRE allows network expansion across a single-protocol backbone environment.

GENSER:

General Service (message): / General Service: A Government designation for a category of people performing various Government functions.

GENTEX:

General Text

GEO:

See Geosynchronous Earth Orbit

GEOSTATIONARY ORBIT:

A satellite orbit, whose period equals the rotation period of the Earth (appears stationary). Artificial satellites are usually placed in a geosynchronous orbit at 35,800km (22,500 miles) altitude. See Geostationary Satellite.

GEOSTATIONARY SATELLITE:

A satellite placed in a geosynchronous earth orbit (GEO), at a precisely timed speed and path to position it over a fixed location within a narrow band of the earth. From the earth, the satellite appears to be stationary. Communications satellites are geostationary satellites.

GEOSYNCHRONOUS EARTH ORBIT (GEO):

A satellite placed in orbit 22,500 miles above the earth. See Geostationary Satellite.

GFI:

See Group Format Identifier

GGP:

Gateway to Gateway Protocol:

1) The protocol used by gateways to exchange routing information

2) MILNET protocol specifying how core routers (gateways) should exchange availability and routing information. GGP uses a distributed shortest-path algorithm.

GGSN:

Gateway GPRS Support Node: A wireless gateway that allows mobile cell phone users to access the Public Data Network (PDN) or specified private IP networks.

Ghz/ gHz / GHz (Gigahertz):

One billion Hertz (cycles per second): A measurement of frequency equal to 10 to 9th power.

Gi INTERFACE:

Reference point between a GPRS network and an external packet data network

GIF:

Graphic Interchange Format: A common format for image files; especially suitable for images containing large areas of the same color. GIF format files of simple images are often smaller than the same file would be if stored in JPEG (Joint Photographic Experts Group) format, but GIF format does not store photographic images as well as JPEG.

GIGABIT (gigabit):

Acronym Gb: 1,000,000,000 bits

GIGABIT ETHERNET:

Standard for a high-speed Ethernet: Approved by the IEEE (Institute of Electrical and Electronics Engineers) 802.3z standards committee in 1996.

GIGABITS PER SECOND:

Acronym Gbps: 1,000,000,000 bits per second

GIGABYTE (gigabyte):

Acronym GB: 1,000,000,000 Bytes

GIGABYTES PER SECOND:

Acronym GBps: 1,000,000,000 Bytes per second

GIGACYCLE:

See Ghz: 1,000,000,000 cycles per second

GIGAHERTZ:

Acronym GHz: 1,000,000,000 cycles per second

GIX:

Global Internet Exchange: Common routing exchange point that allows pairs of networks to implement agreed-upon routing policies. The GIX is intended to allow connectivity to the Internet for networks all over the world.

GLEANING:

The process by which a router automatically derives AARP table entries from incoming packets: Gleaning speeds up the process of populating the AARP table.

GLOBAL DIRECTORY:

A directory system used to tie regional and local directories together.

GLOBAL GROUP:

A security or distribution group that can have users, groups, and computers from its own domain as members: Global security groups can be granted rights and permissions on resources in any domain in the forest (trees). Global groups cannot be created or maintained on computers running Windows XP Professional. However, for Windows XP Professional computers that participate in a domain, domain global groups can be granted rights and permissions at those workstations and can become members of local groups at those workstations.

Gn INTERFACE:

An interface between GSN(s) within the same PLMN in a GPRS network: GTP is a protocol defined on both the Gn and Gp interfaces between GSN(s) in a GPRS network.

GNS:

Get Nearest Server: A request packet sent by a client on an IPX network to locate the nearest active server of a particular type. An IPX network client issues a GNS request to solicit either a direct response from a connected server or a response from a router that tells it where on the inter-network the service can be located. GNS is part of the IPX SAP.

GOODPUT:

Generally refers to the measurement of actual data successfully transmitted from the sender(s) to the receiver(s). This is often a more useful measurement than the number of ATM cells per second throughput of an ATM switch, especially if that switch is experiencing cell loss that results in many incomplete, and therefore unusable, frames.

GOOD TIMES:

See: Virus Hoaxes

GOPHER:

Gopher is a text-based information retrieval system for the Internet. Gopher servers (Gopher client) can be used to search databases around the globe for keywords or subjects. Because a Web Browser usually includes Gopher client capabilities, the Web Browser is superseding Gopher for document retrieval. One advantage of searching with Gopher is that information can be read directly from the servers, no need to copy or save the files to your system first.

GOSIP:

See Government Open Systems Interconnect Profile

GOVERNMENT OPEN SYSTEMS INTERCONNECT PROFILE (GOSIP):

Individual country specified International Standards Organization (ISO) and Open System Interconnection (OSI) functional profiles that have been defined as part of each countries national procurement policies.

Gp INTERFACE:

Interface between GSN(s) within different PLMN(s) in a GPRS network. GTP is a protocol defined on both the Gp and Gn interfaces between GSN(s) in a GPRS network.

GPMDM:

Group MODEM

GPRS:

General Packet Radio Service: A service defined and standardized by the European Telecommunication Standards Institute (ETSI). A technology standard for high speed data transmission over GSM (Global Standard for Mobile) networks

GPS (Global Positioning System); Receivers:

A Global Positioning System can indicate exactly where a person is on Earth at any moment through a satellite triangulation process. All a person needs is a GPS receiver and a clear view of the sky to determine an exact position. The Global Positioning System (GPS) is actually a constellation of 24 active Earth-orbiting satellites.

GRADE OF SERVICE:

A percentage measurement of incomplete, delayed or blocked calls

GRE:

See Generic Routing Encapsulation

GRJ:

A RAS (Registration, Admission, and Status) message sent as a gatekeeper rejection

GROUND:

A term used to express the return (common) side of an electrical circuit.

GROUND START:

1) A method of signaling designed to detect that a circuit is grounded at the far end.

2) A method of signaling used on CO trunk lines to PBX(s). A ground is placed on one side of the two-wire line to indicate that it is in use so the other side of the two-wire interface does not attempt to use the line.

GROUND - START TRUNK:

A phone line that uses a ground instead of a short: Loop-start trunks use a short between tip and ring to signal the central office for a dial tone.

GROUND STATION:

A term used to identify a transmitting/receiving satellite station at an earth (ground) location.

GROUP:

1) An organization on telephone carrier systems, where a full group is a channel equivalent to 12 voice grade channels at 4000 Hz for a total of 48 kHz . A half-group has the equivalent bandwidth of six voice grade channels (24 kHz). Group channels can be used for high-speed data communication.

2) A number of trunks dedicated for identical service in a customer's private branch exchange (PBX) equipment.

3) In the context of network security, a group is a set of users who share one or more resources.

4) A collection of users, computers, contacts, and other groups: Groups can be used as security or as e-mail distribution collectors. Distribution groups are used only for e-mail. Security groups are used both to grant access to resources and as e-mail distribution lists.

GROUP ACCOUNT:

A collection of user accounts. By making a user account a member of a group, it gives the related user all the rights and permissions granted to the group.

GROUP ADDRESS:

1) A method of simultaneously transmitting data to specific pre-arranged groups or stations

2) ‘Multicast Address’: Single packets copied by the network and sent to a specific subset of network addresses. These addresses are specified in the Destination Address Field.

GROUP DELAY:

‘Distortion Delay’: Problem with a communication signal resulting from non-uniform component transmission speeds

GROUP FORMAT IDENTIFIER (GFI):

References the first four bits in a packet header

GROUP MATRIX CARD UNIT:

This unit, located in the Line bay, selects one of two optical signals and routes the signal to the Matrix Card (MC) units in the Matrix bay

GROUP MEMBERSHIPS:

The groups to which a user account belongs: Permissions and rights granted to a group are also provided to its members. In most cases, the actions a user can perform in Windows are determined by the group memberships.

GROUP NAME:

A unique name identifying a local group or a global group to Windows: A groups name cannot be identical to any other group name or user name in its own domain or computer.

GROUP POLICY:

The Microsoft Management Console (MMC) snap-in that is used to edit Group Policy objects.

GROUP POLICY OBJECT:

A collection of Group Policy settings: Group Policy objects are essentially the documents created by the Group Policy snap-in, a Windows utility. Group Policy objects are stored at the domain level, and they affect users and computers contained in sites, domains, and organizational units. In addition, each Windows computer has exactly one group of settings stored locally, called the local Group Policy object.

GROUP 3:

The standard created by the ITU-T relating to fax devices. A Group 3 fax device is a digital machine containing a 14,400 baud MODEM that can transmit an 8 1/2 by 11 inch page in approximately 20 seconds with a resolution of either 203 by 98 dots per inch (dpi) or 203 by 196 dpi (fine), using Huffman code to compress fax data. Group 3 faxes use a standard dial-up telephone line for transmission.

GROUPWARE:

Network oriented production/management software designed to expedite office automation. Groupware provides such features as electronic mail, scheduling, task and appointment reminders, document sharing, project tracking, group calendars, and shared to-do lists.

GRQ:

A RAS message sent as a gatekeeper request

GS:

1) Government Service: A US government entity or Federal Government employees; see next entry

2) FS, GS, RS, US - File Separator, Group Separator, Record Separator, and Unit Separator; Information separators used within data in an optional fashion. The hierarchical relationship will usually be FS is the most inclusive, then GS, then RS and US the least inclusive.

GSM:

Global Standard for Mobile: A digital communication technology used by some carriers to provide PCS (Personal Communication Services): GSM uses TDMA (Time Division Multiple Access) technology and operates in the 900-MHz radio band.

GSN:

GPRS Support Node: GSN(s) refers to the general functions of a group of both GGSN(s) and SGSN(s) in a GPRS network.

GSS:

Generic Service State

GSTN:

See General Switched Telephone Network

GTE:

General Telephone & Electronics

GTOC:

See General Telephone Operating Company

GTOC:

See General Telephone Operating Company

GTP:

GPRS Tunneling Protocol: GTP handles the flow of user packet data and signaling information between the SGSN and GGSN in a GPRS network. GTP is defined in both the Gn and Gp interfaces of a GPRS network. See GTP Tunnel

GTP TUNNEL:

Used to communicate between an external packet data network and a mobile station in a GPRS network: A GTP tunnel is referenced by an identifier called a ‘TID’ and is defined by two associated PDP context requests residing in different GSN(s), a tunnel is created whenever a SGSN sends a Create PDP Context Request in a GPRS network. See GTP

GTT:

Global Title Translation: A function usually performed in a STP. GTT is the procedure by which the destination signaling point and the subsystem number (SSN) is determined from digits (global title) present in the signaling message.

GUARD BAND:

A pre-defined frequency buffer between two adjacent frequencies (bands); the buffer prevents interference (crosstalk) between the two adjacent frequencies.

GUARD FREQUENCY:

1) The unused frequencies between sub channels in FDM systems used to separate channels, thereby preventing crosstalk.

2) A single carrier tone used to indicate that a communications line is prepared to transmit data.

GUARD TONE:

A tone generated by a high-speed dial-up MODEM to ensure there is sufficient bandwidth available on the PSTN circuit for transmission.

GUI:

Graphical User Interface: A user environment that uses pictorial and textual representations of the input and output of applications, and the hierarchical or other data structure in which information is stored. Such conventions as buttons, icons, and windows are typical, and many actions are performed using a pointing device, such as a mouse. Microsoft Windows and the Apple Macintosh are prominent examples of platforms using a GUI.

GUID:

Globally Unique Identifier: A controversial 16-byte number generated by Microsoft programs that uniquely identifies a network, user, computer or document. It is one of the elements of information that can be passed when connecting to an Internet site and it may be stored in cookies

GWS:

GroupWare Server: The entry and exit point for traffic addressed to local NAVSEA DMS users and to off-site users.