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Glossary
T reference point
Used with an S reference point to change a 4-wire ISDN
network to a 2-wire ISDN network.
T1
Digital WAN that uses 24 DS0s at 64K each to create a bandwidth of
1.536Mbps, minus clocking overhead, providing 1.544Mbps of usable
bandwidth.
T3
Digital WAN that can provide bandwidth of 44.763Mbps.
TACACS+
Terminal Access Control Access Control System: An enhanced
version of TACACS, this protocol is similar to RADIUS. See also: RADIUS.
tag switching
Based on the concept of label swapping, where packets or
cells are designated to defined-length labels that control the manner in which
data is to be sent, tag switching is a high-performance technology used for
forwarding packets. It incorporates data-link layer (Layer 2) switching and
network layer (Layer 3) routing and supplies scalable, high-speed switching
in the network core.
tagged traffic
ATM cells with their cell loss priority (CLP) bit set to 1.
Also referred to as discard-eligible (DE) traffic. Tagged traffic can be elimi-
nated in order to ensure trouble-free delivery of higher priority traffic, if the
network is congested. See also: CLP.
TCP
Transmission Control Protocol: A connection-oriented protocol that
is defined at the transport layer of the OSI reference model. Provides reliable
delivery of data.
TCP header compression
A compression process that compresses only
the TCP header information, which is typically repetitive. This would not
compress the user data. See also: compression.
TCP/IP
Transmission Control Protocol/Internet Protocol. The suite of pro-
tocols underlying the Internet. TCP and IP are the most widely known pro-
tocols in that suite. See also: IP and TCP.
TDM
time division multiplexing: A technique for assigning bandwidth on
a single wire, based on preassigned time slots, to data from several channels.
Bandwidth is allotted to each channel regardless of a station's ability to send
data. See also: ATDM, FDM, and multiplexing.
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