Specifications

Glossary
GL-6
Cisco MGX 8850 (PXM45) and MGX 8950 Software Configuration Guide
Release 3, Part Number 78-14788-01 Rev. C0, January 2004
V
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.
VCC
Traffic is carried end-to-end on an ATM network on Virtual Channel Connections, which consist of a
sequence of Virtual Channels between switches linked by VC cross-connects at the switches.
VCI
Each VC within a specific Virtual Path on a link has a unique Virtual Channel Identifier, which is a
16-bit number (see also VPCI).
VP, VPC, VPI
A Virtual Path is a ‘bundle’ of 2
16
Virtual Connections with the same Virtual Path Identifier, i.e. 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.
X
Xbar
Abbreviation for crossbar switch.
XLMI
Extended Link Management Interface.
XM-60
An MGX 8950 card that provides the switching fabric for call processing.