CCNA Cisco Certified Network Associate Study Guide - FTP Server

Glossary 679
full mesh A type of network topology where every node has either a physical
or a virtual circuit linking it to every other network node. A full mesh
supplies a great deal of redundancy but is typically reserved for network
backbones because of its expense. See also: partial mesh.
GNS 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.
GRE 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 connection
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.
guard band The unused frequency area found between two communications
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.
handshake 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, D, and E channels.
HDLC High-Level Data Link Control: Using frame characters, including
checksums, HDLC designates a method for data encapsulation on synchronous
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.