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Cisco VISM Installation and Configuration Guide
Release 3.0, Part Number OL-2521-01 Rev. D0, June 2004
AppendixA VISM and VISM-PR Card Clocking Options
PXM1 Card as Primary Clocking Source
The PXM card option allows you to configure the clocking source origination fr om one of the following
sources:
•An external BITS clock on the PXM card’s T1 or E1 back card port.
•An external OC3 signal on a PXM SONET back card port.
•The PXM card’s internal crystal (default).
The internal crystal is the default and is set as the primary clock source automatically when power is
applied to the chassis.
To use one of the other two clocking sources, complete the following steps:
Step 1 Use the cnfclksrc command to configure the clocking source—external BITS clock or external OC3
signal.
Step 2 Use the cnfln command to configure all VISM lines for local clocking.
The PXM card option makes the PXM the clock source for the all cards in the chassis. The VISM cards
then use this clocking to provide clocking for their associated T1 or E1 lines. Refer to Chapter5, “CLI
Commands,” for more information on VISM comman ds.
Refer to the Cisco MGX 8850 Installation and Configuration Guide and the Cisco MGX 8000 Series
Switch Command Reference for information on the following PXM card clocking commands:
•cnfcbclk
•cnfextclk
•cnfsrmclksrc
•dspcbclk
•dspclkinfo
•dspclksrc
•dspcurclk