HP ProCurve 7000dl Series Basic Management And Configuration Manual page 837

GTS Generic Traffic Shaping. A QoS traffic-shaping mechanism. GTS reduces con-
gestion for outbound traffic by constraining specified traffic to a particular bit
rate. Certain types of traffic can be shaped to meet downstream requirements,
eliminating bottlenecks in topologies with data rate mismatches. GTS is
supported by Data Link Layer protocols like Ethernet, SMDS, and Frame
Relay. GTS uses WFQ as the method for shaping the traffic. See also WFQ
and QoS.
GUI Graphical User Interface. A user interface that substitutes graphics for
characters or text for ease of use.
H
Hash A number generated by running a string of text through an algorithm. The hash
is substantially smaller than the text itself and—because algorithms transform
data in such a way that it is extremely unlikely that some other text will
produce the same hash value—unique.
H-channel An ISDN PRI channel technology developed to offer high transmission speeds
of up to 135 Mbps. Because H channels allow bits to be sent and received in
the same order, they eliminate the delay of reassembling bits.
HDB3 High Density Bipolar order of 3. A line encoding scheme. HDB3 limits the
number of consecutive logical zeros in a data stream so that devices so not
lose synchronization. HDB3 transforms a stream of four logical zeros into
three zero signals and a violation bit of the same polarity as the last logical
one detected. HDB3 is the predominant line encoding scheme used in E-carrier
lines.
HDLC High-level Data Link Control. A Data Link Layer protocol suite used by
network nodes to initiate, maintain, and terminate data transfer. HDLC, which
was originally used for signaling between mainframes and dumb terminals,
requires devices on either end of a link to be designated as either a primary
or secondary device. The HDLC transmission mode determines which devices
can transmit and receive data, and establish and terminate the link. See also
ABM, ARM, and NRM.
HDSL High bit rate DSL. A type of symmetric xDSL. HDSL eliminates the need for
repeaters and employs a 2B1Q modulation technique across the same type of
cabling used with metallic T1 delivery systems. Typically, rather than offering
HDSL to customers as a DSL option, service providers use HDSL to provide
the local loop connection for dedicated T1/E1 carrier lines. HDSL has some
distinct disadvantages: it requires two pairs of wires and does not support
analog voice.
Appendix B: Glossary
B-23