Cisco BPX 8600 Series, Руководство по установке и настройке

Страница: 621 / 630

Glossary
21
Cisco BPX 8600 Series Installation and Configuration
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
V
V.21 A CCITT interface standard often used for data transmission over modems.
V.35
A data communications interface standard adopted by the CCITT. Often used for data circuits
operating at 56 Kbps and above.
VAD (Voice Activity
Detection) Used to statistically compress voice by not sending packets in the absence of speech.
VBR (Variable Bit
Rate)
Connection type for variable bit rate traffic such as bursty data. Compare with CBR and ABR.
VC
ATM and Frame Relay traffic is carried in Virtual Channels which are set up between adjacent ATM
or Frame Relay switches before data transmission occurs. An ATM link between switches may
support up to 2
28
different VCs, although a small number of VCs is reserved for special purposes.
VCI
Each VC within a specific Virtual Path on a link has a unique Virtual Channel Identifier, which is a
16-bit number .
VC Descriptor
Template
A component of a Service Class Template which contains platform-specific VC configurations that
are indexed primarily by service type. Together with a Class of Service Buffer (CoSB) descriptor
template, it defines a Service Class Template (SCT).
VC_Q
Frame relay buffer allocation parameter that specifies the maximum queue size reserved in the FRP
card for the FR connection.
virtual circuit
A circuit that acts like it is an individual transmission path but is actually shared with other circuits
over a single transmission path. Compare with PVCs.
Virtual Trunks
A Virtual Trunks is a Virtual Path Connection which appears to VSI masters as ordinary trunk (except
that the trunk supports 64k VCs at most). In a VSI platform, a virtual trunk endpoint has its own
logical interface.
VNS
The adjunct processor used in the INS Voice Network Switching application. The VNS is co-located
with and connected to an IGX switch.
Voice Network
Switching
An INS application used to provide voice or data switched virtual circuits over a Cisco WAN
switching network for PBXes using either QSIG or DPNSS signalling.
VP, VPC, VPI
A Virtual Path is a bundle of 2
16
Virtual Connections with the same Virtual Path Identifier, that is, the
first 12 bits of the VPCI. Most ATM switches can switch VPs using only a single cross-connect
(instead of up to 2
16
). An end-to-end sequence of VPs cross-connected at the intermediate switches
is a Virtual Path Connection.
VPCI
Each VC on a link has a unique Virtual Path and Channel Identifier, which is a 28-bit number. The
VPCI consists of a 12-bit VPI concatenated with a 16-bit VCI.
VSI
Virtual Switch Interface: this is a proposed common control interface to all Cisco MSSBU switches.
It embodies both connection management and switch configuration discovery capabilities.
VSI 2
Virtual Switch Interface, Protocol Version 2: this is revision 2 of a proposed common control interface
to all MSSBU switches. It embodies both connection management and switch configuration discovery
capabilities.