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Glossary
GL-9
Cisco ASR 1000 Series Aggregation Services Routers Hardware Installation and Initial Configuration Guide
OL-13208-03
Tracing
A function on the ASR 1000 Series Routers that logs internal events. Tracing cannot be disabled on the
Cisco ASR 1000 Series Router, and all tracing logs are stored in trace files.
Trace files
Files that are automatically generated on the Cisco ASR 1000 Series Router that store trace data. Trace
files are usually stored automatically in a storage directory and are often useful for customer support
purposes.
U
UDLR
Uni-Directional Link Routing
UTP
Unshielded twisted pair
V
VAC
Volts alternating current
VDC
Volts direct current
VCCV
Virtual Circuit Connection Verification
vDBE
Virtual DBE. Represents a resource partition within a DBE. A vDBE is a type of media gateway. Each
vDBE can be controlled by a separate SBE using the H.248 protocol.
VID
Version ID
VRF
Virtual Routing and Forwarding Instances
Virtual circuit
Logical circuit created to ensure reliable communication between two network devices. A virtual
circuit is defined by a VPI/VCI pair, and can be either permanent (PVC) or switched (SVC). Virtual
circuits are used in Frame Relay and X.25. In ATM, a virtual circuit is called a virtual channel.
VoIP
Voice over Internet Protocol. The capability to carry normal telephony-style voice over an IP-based
internet with POTS-like functionality, reliability, and voice quality. VoIP enables a router to carry voice
traffic (for example, telephone calls and faxes) over an IP network. In VoIP, the DSP segments the voice
signal into frames, which then are coupled in groups of two and stored in voice packets. These voice
packets are transported using IP in compliance with ITU-T specification H.323.
VPI
Virtual path identifier. 8-bit field in the header of an ATM cell. The VPI, together with the VCI,
identifies the next destination of a cell as it passes through a series of ATM switches on its way to its
destination. ATM switches use the VPI/VCI fields to identify the next VCL that a cell needs to transit
on its way to its final destination. The function of the VPI is similar to that of the DLCI in Frame Relay.
VRRP
Virtual Router Redundancy Protocol
W