Cisco ONS 15327 User Documentation page 538

Glossary
TLS
Transparent LAN Service. Provides private network service across a SONET backbone.
Trap
Message sent by an SNMP agent to an NMS (CTM), console, or terminal to indicate the occurrence of a significant event, such
as an exceeded threshold.
Tributary
The lower-rate signal directed into a multiplexer for combination (multiplexing) with other low- rate signals to form an
aggregate higher rate level.
Trunk
Network traffic travels across this physical and logical connection between two switches. A backbone is composed of a number
of trunks. See also Backbone.
Tunneling
Architecture that is designed to provide the services necessary to implement any standard point-to-point encapsulation scheme.
See also encapsulation.
U
Unicast
The communication of a single source to a single destination.
Unprotected card
Cards that are not included in a protection scheme. An unprotected card failure or a signal error results in lost data.
UPSR
Unidirectional Path Switched Ring. Path-switched SONET rings that employ redundant, fiber- optic transmission facilities in
a pair configuration. One fiber transmits in one direction and the backup fiber transmits in the other. If the primary ring fails,
the backup takes over.
Upstream
Set of frequencies used to send data from a subscriber to the headend.
UTC
Coordinated Universal Time. Time zone at zero degrees longitude.
V
Virtual fiber
Converts each fiber into multiple fibers to allow signals that are carried at different rates use the same fiber-optic cable.
Cisco ONS 15327 User Documentation, R3.3
GL-14
June 2002