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Glossary
GL-7
Cisco ASA 5500 Series Configuration Guide using ASDM
FragGuard
Provides IP fragment protection and performs full reassembly of all ICMP error messages and virtual
reassembly of the remaining IP fragments that are routed through the ASA.
FTP
File Transfer Protocol. Part of the TCP/IP protocol stack, used for transferring files between hosts.
G
GGSN
gateway GPRS support node. A wireless gateway that allows mobile cell phone users to access the
public data network or specified private IP networks.
global
configuration mode
Global configuration mode lets you change the ASA configuration. All user EXEC, privileged EXEC,
and global configuration commands are available in this mode. See also user EXEC mode, privileged
EXEC mode, command-specific configuration mode.
GMT
Greenwich Mean Time. Replaced by UTC (Coordinated Universal Time) in 1967 as the world time
standard.
GPRS
general packet radio service. A service defined and standardized by the European Telecommunication
Standards Institute. GPRS is an IP-packet-based extension of GSM networks and provides mobile,
wireless, data communications
GRE
Generic Routing Encapsulation described in RFCs 1701 and 1702. GRE is a tunneling protocol that
can encapsulate a wide variety of protocol packet types inside IP tunnels, creating a virtual
point-to-point link to routers at remote points over an IP network. By connecting multiprotocol
subnetworks in a single-protocol backbone environment, IP tunneling using GRE allows network
expansion across a single protocol backbone environment.
GSM
Global System for Mobile Communication. A digital, mobile, radio standard developed for mobile,
wireless, voice communications.
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 on both the Gn and Gp interfaces
of a GPRS network.
H
H.225
A protocol used for TCP signaling in applications such as video conferencing. See also H.323 and
inspection engine.
H.225.0
An ITU standard that governs H.225.0 session establishment and packetization. H.225.0 actually
describes several different protocols: RAS, use of Q.931, and use of RTP.
H.245
An ITU standard that governs H.245 endpoint control.
H.320
Suite of ITU-T standard specifications for video conferencing over circuit-switched media, such as
ISDN, fractional T-1, and switched-56 lines. Extensions of ITU-T standard H.320 enable video
conferencing over LANs and other packet-switched networks, as well as video over the Internet.