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Cisco Broadband Cable Command Reference Guide
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Chapter 3 Cisco CMTS Show Commands
show controllers clock-reference
show controllers clock-reference
To display hardware information, register values, and current counters for the TCC+ card or the
Cisco cable clock card, use the
show controllers clock-reference
command in privileged EXEC mode.
show controllers clock-reference
Syntax Description
This command has no keywords or arguments.
Command Modes
Privileged EXEC
Command History
Usage Guidelines
To reset the counters that are displayed with the
show controllers clock-reference
command, use the
cable clock clear-counters
command.
Note
This command is not applicable on the SC train.
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:
•
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.
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.
Examples
The following is sample output from the
show controllers clock-reference
command for a
Cisco uBR7246 VXR router with a national clock card:
Release
Modification
12.1(1a)T1
This command was introduced.
12.1(2)EC1
This command was supported on the EC train.
12.2(2)XF
This command was supported for the TCC+ card on Cisco uBR10012
routers.
12.2(4)BC1
Support was added to the Release 12.2 BC train.
