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Chapter 3
Cisco CMTS Show Commands
show cable clock
To display clock reference status information for the clock card, use the show cable clock command in
user EXEC or privileged EXEC mode.
Syntax Description
This command has no arguments or keywords.
Command Modes
User EXEC or Privileged EXEC
Command History
Release
12.1(1a)T1
12.1(2)EC1
12.2(1)XF1,
12.2(4)BC1
This command is not supported on the SC train.
Note
Usage Guidelines
This command supports the Cisco CMTS clock feature set, which provides a synchronized clock for
improved Voice-over-IP (VoIP) operations. The clock feature set requires one of the following
configurations:
•
•
Only these cable interface cards support the external clock card reference from a clock card to distribute
that signal to CMs or set-top boxes (STBs) attached to the specific network segments. You can use other
cable interface cards, such as the Cisco uBR-MC16C, with the clock card, but these other cable
interfaces will not synchronize their downstream SYNC messages with the external clock source.
Each CM or STB must also support VoIP applications and the clock feature set. For example, the
Cisco uBR924, running Cisco IOS Release 12.0(7)T or later, supports clock card feature automatically.
This command does not appear if a clock card is not installed in the system.
Note
OL-1581-08
show cable clock
Modification
This command was introduced.
This command was supported on the EC train.
This command was supported for the Cisco uBR10012 universal broadband
router.
A Cisco uBR10012 router with one or two TCC+ cards that are connected to an external national
clock source.
A Cisco uBR7246 VXR router using a Cisco uBR-MC16S, Cisco uBR-MC16E, Cisco uBR-
MC28C, or Cisco uBR-MC28C-BNC cable interface line card. The router must also be equipped
with a Cisco cable clock card and be running Cisco IOS 12.1(1a)T1, 12.1(2)EC1, or a later release.
The Cisco cable clock card should be connected to an external national clock source.
Cisco Broadband Cable Command Reference Guide
show cable clock
3-15
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