A-1
Cisco Cable Clock Card Hardware Installation Guide for the Cisco uBR7246VXR Universal Broadband Router
OL-26705-01
A P P E N D I X
A
Clock Source Paths
The schematics in this appendix display the various clock source paths established by the Cisco Cable
Clock Card in a Cisco uBR7246 VXR depending on your external connection(s) and configuration.
Figure A-1
Primary External Clock Source
PA
PRI
SRC
Midplane
clk mux
Port adapters w/
internal clocking
External SRCs
PRI SEC
Clock card
clk mux
Clock recovery
and filter chips
PRI clk
PRI LOS
SEC clk
SEC LOS
20.48
MHz
To line
cards
No cable clock
source-midplane
Cable clock
force primary
(default)
Clock card primary source to midplane 8 kHz
PA
PA
SEC
SRC
31498
PA
