Vodavi NomadIP, Руководство пользователя

Страница: 118 / 120

Glossary
116
December, 2005 Vodavi Telenium IP Product Guide
mobility ▪ presence ▪ collaboration ▪ convergence
Token Ring In a Token Ring network, the presence of a token (which is simply a particular bit setting) in a
continually circulating transmission stream allows a device to change the bit setting (thus taking
the token) and put a message in its place. The receiver of the message elsewhere in the token
ring network removes the message and resets the bit setting (thus putting the token back) so
that someone else in the ring of devices will be able to have a turn at using that message space.
Topology A description of the physical layout of a network.
Transponder A wireless communications, monitoring, or control device that picks up and automatically
responds to an incoming signal. May be either passive or active.
Tunneling Tunneling, also known as port forwarding, is the transmission of data intended for use only
within a private, usually corporate network through a public network in such a way that the
routing nodes in the public network are unaware that the transmission is part of a private
network. Tunneling allows the use of the Internet, which is a public network, to convey data on
behalf of a private network.
UDP User Datagram Protocol. User Data Protocol is part of the TCP/IP protocol suite. It was created
to provide a way for applications to access the connectionless features of IP. UDP provides for
exchange of datagrams without acknowledgements or guaranteed delivery. This protocol is
normally bundled with IP-layer software. UDP is a transport layer (layer 4 of the OSI model),
connectionless mode protocol, providing a (potentially unreliable, unsequenced, and/or
duplicated) datagram mode of communication for delivery of packets to a remote or local user.
Ultra Wide
Band (UWB) ultra wideband (UWB): (see also: digital pulse wireless) is a wireless technology for transmitting
large amounts of digital data over a wide spectrum of frequency bands with very low power for a
short distance. Ultra wideband broadcasts very precisely timed digital pulses on a carrier signal
across a very wide spectrum (number of frequency channels) at the same time. UWB can carry a
huge amount of data over a distance up to 230 feet at very low power (less than 0.5 milliwatts),
and has the ability to carry signals through doors and other obstacles that tend to reflect signals
at more limited bandwidths and a higher power.
Unicast In contrast to a broadcast, unicast datagrams are directed at a particular device on the network.
Utilization A measurement of the amount of bandwidth used. Stated in terms of percentage of the total
available.
Vocoder A codec. See definition above.
VoIP Voice over Internet Protocol. The technology used to transmit voice conversations over a data
network using the Internet Protocol. Such data network may be the Internet or an Intranet
(LAN). There are several potential benefits to moving voice over a network using Internet
Protocol including cost savings, one managed network, easier moving of phones in an office, and
new, integrated services including unified messaging, Web integration for multi-media
communications, etc.
VOIP Gateway A VoIP trunk gateway is an interface that facilitates the use of plain old telephone service (POTS)
equipment, such as conventional phone sets and fax machines, with a voice over IP (VoIP)
network.
VoWLAN VoWLAN (Voice over WLAN, sometimes called wireless VoIP, Wi-Fi VoIP): a method of routing
telephone calls for mobile users over the Internet using the technology specified in IEEE 802.11b.
Routing mobile calls over the Internet makes them free, or at least much less expensive than
they would be otherwise.
VPN Virtual Private Network: A connection over a public network like the Internet which is encrypted
at both ends to provide exclusive and more secure access.
WAN Wide-Area Network. A computer network that spans a relatively large geographical area.
Typically, a WAN consists of two or more local-area networks (LANs).
WAP(1) Wireless Access Point. See Access Point