G

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.804

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

gateway

In the IP community, an older term referring to a routing device. Today, the term router is used to describe nodes that perform this function, and gateway refers to a special-purpose device that performs an application layer conversion of information from one protocol stack to another. Compare with router.

Gateway Discovery Protocol

See GDP in the Cisco Systems Terms and Acronyms section.

gateway host

In SNA, a host node that contains a gateway SSCP.

gateway NCP

NCP that connects two or more SNA networks and performs address translation to allow cross-network session traffic.

Gateway-to-Gateway Protocol

See GGP.

GB

gigabyte. Approximately 1,000,000,000 bytes.

GBps

gigabytes per second.

Gb

gigabit. Approximately 1,000,000,000 bits.

Gbps

gigabits per second.

GCAC

generic connection admission control. In ATM, a PNNI algorithm designed for CBR and VBR connections. Any node can use GCAC to calculate the expected CAC behavior of another node given than node's advertised link metrics and the QOS of a connection setup request. See also CAC.

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 GDP in the Cisco Systems Terms and Acronyms section.

generic connection admission control

See GCAC.

generic routing encapsulation

See GRE in the Cisco Systems Terms and Acronyms section.

Get Nearest Server

See GNS.

GGP

Gateway-to-Gateway Protocol. MILNET protocol specifying how core routers (gateways) should exchange reachability and routing information. GGP uses a distributed shortest-path algorithm.

GHz

gigahertz.

gigabit

Abbreviated Gb.

gigabits per second

Abbreviated Gbps.

gigabyte

Abbreviated GB.

gigabytes per second

Abbreviated GBps.

gigahertz

Abbreviated GHz.

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. See also AARP.

GNS

Get Nearest Server. 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 internetwork the service can be located. GNS is part of the IPX SAP. See also IPX and SAP (Service Advertisement Protocol).

GOSIP

Government OSI Profile. U.S. government procurement specification for OSI protocols. Through GOSIP, the government has mandated that all federal agencies standardize on OSI and implement OSI-based systems as they become commercially available.

Government OSI Profile

See GOSIP.

grade of service

Measure of telephone service quality based on the probability that a call will encounter a busy signal during the busiest hours of the day.

graphical user interface

See GUI.

GRE

See GRE in the Cisco Systems Terms and Acronyms section.

ground station

Collection of communications equipment designed to receive signals from (and usually transmit signals to) satellites. Also called a downlink station.

group address

See multicast address.

group delay

See distortion delay.

guard band

Unused frequency band between two communications channels that provides separation of the channels to prevent mutual interference.

GUI

graphical user interface. User environment that uses pictorial as well as textual representations of the input and output of applications and the hierarchical or other data structure in which information is stored. Conventions such 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 utilizing a GUI.