Specifications

Glossary
GL-12
Cisco ONS 15454 Troubleshooting and Maintenance Guide
November 2001
Transponder
Optional devices of a DWDM system providing the conversion of one optical wavelength to a precision narrow band
wavelength.
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.
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.
V
Virtual fiber
A fiber that carries signals at different rates and uses the same fiber optic cable.
Virtual ring
Entity in a source-route bridging (SRB) network that logically connects two or more physical rings together either locally or
remotely. The concept of virtual rings can be expanded across router boundaries.
Virtual wires
Virtual wires route external alarms to one or more alarm collection centers across the SONET transport network.