A-2
Cisco Cable Clock Card Hardware Installation Guide for the Cisco uBR7246VXR Universal Broadband Router
OL-26705-01
Appendix A Clock Source Paths
Figure A-2
Secondary External Clock Source
Figure A-3
Secondary External Clock Source Driving Midplane
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 secondary
Clock card primary source to midplane 8 kHz
PA
PA
SEC
SRC
31497
PA
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 secondary
Clock card primary source to midplane 8 kHz
PA
PA
SEC
SRC
31499
PA