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Ταξινομημένα προς το παρόν Κατά τελευταία ενημέρωση (φθίνουσα) Ταξινόμηση χρονολογικά: Κατά τελευταία ενημέρωση
X.21ITU-T standard for serial
communications over synchronous digital lines. The X.21 protocol is
used primarily in Europe and Japan. |
WWWWorld Wide Web.
Large network of Internet servers providing hypertext and
other services to terminals running client applications
such as a WWW browser. |
WANWide-area network.
Data communications network that serves users across a
broad geographic area and often uses transmission devices
provided by common carriers. Frame Relay, SMDS, and X.25
are examples of WANs. |
VLSMVariable-length subnet mask.
Ability to specify a different subnet mask for the same network
number on different subnets. VLSM can help optimize available
address space. |
VLANVirtual LAN. Group of
devices on a LAN that are configured (using management software) so
that they can communicate as if they were attached to the same wire,
when in fact they are located on a number of different LAN segments.
Because VLANs are based on logical instead of physical connections,
they are extremely flexible. |
UTPUnshielded twisted-pair.
Four-pair wire medium used in a variety of networks. UTP does not
require the fixed spacing between connections that is necessary with
coaxial-type connections. There are five types of UTP cabling
commonly used: Category
1 cabling, Category
2 cabling, Category
3 cabling, Category
4 cabling, and Category
5 cabling. Compare with STP. |
USENETInitiated in 1979, one of the oldest
and largest cooperative networks, with over 10,000 hosts and a
quarter of a million users. Its primary service is a distributed
conferencing service called news. |
URLUniversal Resource Locator.
Standardized addressing scheme for accessing hypertext documents and
other services using a WWW browser. |
UPSUninterruptable power supply.
Backup device designed to provide an uninterrupted power source in
the event of a power failure. They are commonly installed on all
file servers and wiring hubs. |
UNIXOperating system developed in 1969 at
Bell Laboratories. UNIX has gone through several iterations since
its inception. These include UNIX 4.3 BSD (Berkeley Standard
Distribution), developed at the University of California at
Berkeley, and UNIX System V, Release 4.0, developed by AT&T. |
UDPUser Datagram Protocol.
Connectionless transport layer protocol in the TCP/IP protocol
stack. UDP is a simple protocol that exchanges datagrams without
acknowledgments or guaranteed delivery, requiring that error
processing and retransmission be handled by other protocols. UDP is
defined in RFC 768. |
twisted pairRelatively low-speed transmission
medium consisting of two insulated wires arranged in a regular
spiral pattern. The wires can be shielded or unshielded. Twisted
pair is common in telephony applications and is increasingly common
in data networks. |
tunnelingArchitecture that is designed to
provide the services necessary to implement any standard
point-to-point encapsulation |
tree topologyLAN topology similar to a bus
topology, except that tree networks can contain branches with
multiple nodes. Transmissions from a station propagate the length of
the medium and are received by all other stations. |
transparent bridgingBridging scheme often used in Ethernet
and IEEE 802.3 networks in which bridges pass frames along one hop
at a time based on tables associating end nodes with bridge ports.
Transparent bridging is so named because the presence of bridges is
transparent to network end nodes. |
traffic shapingUse of queues to limit surges that can
congest a network. Data is buffered and then sent into the network
in regulated amounts to ensure that the traffic will fit within the
promised traffic envelope for the particular connection. Traffic
shaping is used in ATM, Frame Relay, and other types of networks.
Also known as metering, shaping, and smoothing. |
TOSType of service.
Field within an IP datagram that indicates how the datagram should
be handled. |
Token RingToken-passing LAN developed and
supported by IBM. Token Ring runs at 4 or 16 Mbps over a ring
topology. Similar to IEEE 802.5. |
token busLAN architecture using token passing
access over a bus topology. This LAN architecture is the basis for
the IEEE 802.4 LAN specification. |
tokenFrame that contains control
information. Possession of the token allows a network device to
transmit data onto the network. |