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Gigabit Ethernet
1000Mbps version of the IEEE 802.3. Fast Ethernet
offers a speed increase of 10 times that of the 10BaseT Ethernet specification
while preserving qualities such as frame format, MAC, mechanisms, and MTU.
Get Nearest Server: On an IPX network, a request packet sent by a
customer for determining the location of the nearest active server of a given
type. An IPX network client launches a GNS request to get either a direct
answer from a connected server or a response from a router disclosing the
location of the service on the internetwork to the GNS. GNS is part of IPX
and SAP. See also: IPX and SAP.
A process that activates an interface that has been deactivated by
the pruning process. It is initiated by an IGMP membership report sent to the
Generic Routing Encapsulation: A tunneling protocol created by
Cisco with the capacity for encapsulating a wide variety of protocol packet
types inside IP tunnels, thereby generating a virtual point-to-point connec-
tion to Cisco routers across an IP network at remote points. IP tunneling
using GRE permits network expansion across a single-protocol backbone
environment by linking multiprotocol subnetworks in a single-protocol
backbone environment.
Group of Four
Used by Cisco Local Management Interface on Frame
Relay networks to manage the permanent virtual circuits (PVCs). See also: PVC.
guard band
The unused frequency area found between two communica-
tions channels, furnishing the space necessary to avoid interference between
the two.
half duplex
The capacity to transfer data in only one direction at a time
between a sending unit and receiving unit. See also: full duplex.
Any series of transmissions exchanged between two or more
devices on a network to ensure synchronized operations.
H channel
High-speed channel: A full-duplex, ISDN primary rate channel
operating at a speed of 384Kbps. See also: B channel, D channel, and
E channel.
High-Level Data Link Control: Using frame characters, including
checksums, HDLC designates a method for data encapsulation on synchro-
nous serial links and is the default encapsulation for Cisco routers. HDLC is
a bit-oriented synchronous Data Link layer protocol created by ISO and
derived from SDLC. However, most HDLC vendor implementations
(including Cisco's) are proprietary. See also: SDLC.
Copyright ©2001 SYBEX , Inc., Alameda, CA