Motorola SURFBOARD SVG2500 - Manual (Page 160)

17 GLOSSARY
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H
TERM DEFINITION
H.323 A suite of protocols created by the ITU for interactive video
conferencing, data sharing, and audio applications such as VoIP.
half-duplex Network where only one device at a time can transmit data. See
also full-duplex.
headend A location that receives TV programming, radio
programming, data, and telephone calls that it modulates
onto the HFC network. It also sends return data and telephone
transmissions. Headend equipment includes transmitters,
preamplifiers, frequency terminals, demodulators, modulators,
and other devices that amplify, filter, and convert incoming
broadcast TV signals to wireless and cable channels.
header The data at the beginning of a packet that identifies what is in the
packet.
hexadecimal A base-sixteen numbering system that uses sixteen sequential
numbers (0 to 9 and the letters A to F) as base units before
adding a new position. On computers, hexadecimal is a
convenient way to express binary numbers.
HFC A hybrid fiber/coaxial cable network uses fiber-optic cable as the
trunk and coaxial cable to the subscriber’s premises.
hop The interval between two routers on an IP network. The number
of hops a packet traverses toward its destination (called the hop
count) is saved in the packet header. For example, a hop count
of six means the packet has traversed six routers. The packet
hop count increases as the time-to-live (TTL) value decreases.
host In IP, a host is any computer supporting end-user applications or
services with full two-way network access. Each host has a
unique host number that, when combined with the network
number, forms its IP address.
Host also can mean:
• A computer running a web server that serves pages for
one or more web sites belonging to organization(s) or
individuals
• A company that provides this service
• In IBM environments, a mainframe computer
HTML Hyper Text Markup Language
hub On a LAN, a hub is a device that connects multiple hosts to the
LAN. A hub performs no data filtering. See also bridge and router.
An IP hub is typically a unit on a rack or desktop.