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Cisco VISM Installation and Configuration Guide
Release 3.0, Part Number OL-2521-01 Rev. D0, June 2004
APPENDIX
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VISM and VISM-PR Card Clocking Options

An MGX 8000 Series platform, consisting of PXM and VISM cards, should have one primary clocking
source. To avoid conflicts and to ensure proper operation, it is important that the set tings fo r cloc kin g
options in both card types are considered together. You must use one of the following primary clocking
source options, which are supported by the VISM/PXM interface:
•PXM1, PXM1E, and PXM45 cards—Provides clocking for all VISM cards in the c hassi s.
•A VISM card—Provides clocking for the PXM1, which then provides clocking to the entire c hassis.
•A VISM-PR card—Provides clocking for the PXM1E or PXM45 card, which then provides clocking
to the entire chassis.

PXM1 Card as Primary Clocking Source

Figure A-1 shows the PXM card primary clocking source option in which the clock source originates at
the PXM side of the VISM/PXM in te r fac e.
FigureA-1 VISM Configured for Local Clocking
External BITS (T1/E
1)
Network (OC3)
Internal crystal
Clocking on
T1/E1 lines to
PBX or CO
MGX 8850
VISM
V
ISM lines configured
f
or local clocking
Bus
62874