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G.168 is an ITU-T standard for eliminating the echo caused by the sound of your voice reverberating in the telephone receiver while you talk.



G.711 is a Pulse Code Modulation (PCM) waveform codec. G.711 provides very good sound quality but requires 64kbps of bandwidth. G.711u is used mainly in North America and G.711a is used in most of the rest of the world. See also Codec.



The G.723.1 codec uses Low-Delay Code-Excited Linear Prediction (LD-CELP) to code audio in 30-millisecond frames. The standard supports two bitrates, 6.3 kbps and 5.3 kbps. G.723.1 provides toll-quality sound and requires very little bandwidth.



G.726 is an Adaptive Differential Pulse Code Modulation (ADPCM) waveform codec that uses a lower bit rate than standard PCM conversion. G.726 operates at 16, 24, 32 or 40 kbps.



G.729 is an Analysis-by-Synthesis (AbS) hybrid waveform codec that uses a filter based on information about how the human vocal tract produces sounds. G.729 provides good sound quality and reduces the required bandwidth to 8kbps.



G.993.2 is an ITU standard that defines VDSL2. (also known as port bonding) allows subscribers to connect to an ISP using data streams spread over multiple DSL lines. The total available bandwidth for the subscriber then becomes the sum of the bandwidth available for each of the subscriber’s line connections. As well as extra bandwidth, additional DSL lines also provide backup support.


G.lite Rate Limit

The G.lite upstream transmission rate is usually limited to 512 Kbps. Disabling the G.lite rate limit allows the G.lite upstream transmission rate to be greater than 512 Kbps.



G-plus is an enhancement to the IEEE 802.11g wireless standard. It increases wireless transmission speeds by allowing larger frames to be sent.



A Single-pair High-speed Digital Subscriber Line is a symmetrical, bi-directional DSL service that operates on one twisted-pair wire. The “G.” in “G.SHDSL” refers to ITU (International Telecommunication Union) “G” standards. G.SHDSL provides data rates from 192kbps up to 2.3 Mbps at distances of 6,000 feet to 20,000 feet on 26 AWG copper. See also DSL.



GARP allows network devices to register and de-register attribute values with other GARP participants within a bridged LAN.



A gateway is a computer system or other device that acts as a translator between two systems that do not use the same communication protocols, data formatting structures, languages and/or architecture.


Gateway Policy

A gateway policy identifies the IPSec routers at either end of a VPN tunnel and specifies the authentication, encryption and other settings needed to negotiate a phase 1 IKE SA.



A GBIC is a transceiver that changes optical signals to electric currents and vice versa, with a one gigabit per second (1Gbps) or higher data transfer rate. Common used to connect Ethernet and fiber optic networks.



In the Simple Network Management Protocol (SNMP), a GETNEXT request is issued by an SNMP manager to an SNMP agent requesting information on the next variable (OID) in the MIB tree after the one specified. The agent returns a message, providing either the data or an error report.



Gateway-to-Gateway Protocol is an Internet protocol that specifies how gateway routers communicate with each other.


Gigabit Ethernet

Gigabit Ethernet (IEEE 802.3z standard) uses Ethernet over copper technology to increase network data rates to 1Gbps. It uses standard 4-pair Category 5 copper cabling.


Global Address

An IPv6 global address uniquely identifies a device on the Internet. It is similar to a “public IP address” in IPv4. The global ID is the network identifier or prefix of the global address and is used for routing. This may be assigned by service providers. The subnet ID is a number that identifies the subnet of a site.



Gigabit-capable PON (GPON) is a PON technology defined in ITU-T G.984 standard. It provides up to 1.25Gbps for upstream transmissions and up to 2.5Gbps for downstream transmissions. GPON can coexist with ATM (Asynchronous Transfer Mode), Ethernet, and others.



GPRS (General Packet Radio Service) is a packet-switched wireless communication service. GPRS is based on GSM and existing services such as circuit-switched cellular phone connections and the Short Message Service (SMS). GPRS is charged per megabyte of transferred data, while traditional circuit-switched service is billed per minute of connection time, independent of whether the user has actually transferred data or has been in idle state. GPRS is also known as 2.5G, a technology between the second (2G) and third (3G) generations of mobile telephony.



The primary function of GPS is to provide precise geographical location information to ground-based, maritime and airborne receiver units. The NAVSTAR GPS (Global Positioning System), which is operated by the United States Air Force’s 50th Space Wing for civilian purposes, uses a constellation of satellites in medium Earth orbit whose orbital paths ensure that multiple satellites are visible from any point on Earth at any time.



WiMAX uses the precision of GPS satellites’ timing mechanism (which is necessary for GPS’s primary positioning function) to time its transmissions. GPS satellites use regularly-synchronized atomic clocks. Precise transmission timing is critical to WiMAX operation in areas where there are multiple base stations operating on the same frequencies. This is because WiMAX devices use Time Division Duplexing (TDD) to allocate certain specific times for transmitting data, and other specific times for receiving data (allowing a connection to use a single channel). The TDD ratio (uplink to downlink) can be defined by the operator.


Ground Start

This is a type of analog voice grade access line signaling that requires the customer interface to provide a ground on the ring conductor at the network interface to initiate service requests.



The Global System for Mobile communication (GSM) is a globally accepted standard for digital cellular communication. Mobile phones that use the GSM-based mobile phone network use SIM cards. See also SIM.



A GSTN denotes an analog network (PSTN) or digital network (ISDN).


Guest WLAN

Guest WLAN allows you to set up a wireless network where users can access the Internet via the AP, but not other networks connected to the AP.



Graphical User Interface (GUI) is the set of configuration screens you see to set up your device. The GUI can also display status and other reports.



GVRP is a registration protocol that defines a way for 802.1Q VLAN-aware switches to register necessary VLAN members on ports across the network.