Appendix D. Glossary T1 ESF CSU ACE
62 © 2004 ADTRAN, Inc 61204025L1-1B
HDLC
high level data link control. A generic link-level communications protocol developed by the International Orga-
nization for Standardization (ISO). HDLC manages synchronous code-transparent, serial information transfer
over a link connection. See also SDLC.
hop
A single trunk line between two switches in a frame relay network. An established PVC consists of a certain
number of hops, spanning the distance form the ingress access interface to the egress access interface within the
network.
host computer
The primary or controlling computer in a multiple computer operation.
in-band
Signaling (dialing, diagnostics, management, configuration, etc.) over the same channel used for data.
ingress
Frame relay frames leaving from an access device in a direction toward the frame relay network.
interface device
Provides the interface between the end device(s) and a frame relay network by encapsulating the user’s native
protocol in frame relay frames and sending the frames across the frame relay backbone. See also encapsulation
and frame-relay-capable interface device.
ISDN
Integrated Services Digital Network. A network architecture that enables end-to-end digital connections. The
network supports diverse services through integrated access arrangements and defines a limited set of standard,
multipurpose interfaces for equipment vendors, network providers, and customers. Networking with a public
switched telephone network is retained.
LAN
local area network. A privately owned network that offers high-speed communications channels to connect
information processing equipment in a limited geographic area.
out-of-band
Signaling that is separated from the channel carrying information (voice, data, video, etc.). Typically the sepa-
ration is accomplished by a filter. The signaling includes dialing and other supervisory signals.
packet
A message containing both control information and data. The control information is used for routing the packet
through a network to its final destination. Contrast with frame relay frame.
packet-switching network
A telecommunications network based on packet-switching technology, wherein a transmission channel is occu-
pied only for the duration of the transmission of the packet. Contrast with frame relay network.
parameter
A numerical code that controls an aspect of terminal and/or network operation. Parameters control such aspects
as page size, data transmission speed, and timing options.
