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ATM Switch Router Software Configuration Guide
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Chapter3 Initially Configuring the ATMSwitch Router
Configuring Network Clocking
Configuring the Transmit Clocking Source
To configure where each interface receives its transmit clocking, perform the following steps, beginning
in global configuration mode:
Caution If the Network Clock Distribution Protocol (NCDP) is running on an interface, you should not override
that port’s clock source by configuring it to free-running or loop-timed. Doing so could cause
synchronization problems, particularly in the case of loop-timed, whic h could cause a clocking loop to
be formed on a link. See the Configuring Network Cloc king with NCDP, page 3-13.
Example
The following example configures ATM interface 3/0/0 to receive its transmit clocking from a
network-derived source:
Switch(config)# interface atm 3/0/0
Switch(config-if)# clock source network-derived

Displaying the Network Clocking Configuration

To show the switch’s network clocking configuration, use the following privileged EXEC commands:
Examples
The following example shows the configured network clock sources on a Catalyst8510 MSR or
LightStream 1010:
Switch# show network-clocks
clock configuration is NON-Revertive
Priority 1 clock source: ATM1/0/0
Priority 2 clock source: ATM1/1/0
Priority 3 clock source: No clock
Priority 4 clock source: No clock
Priority 5 clock source: System clock
Current clock source:System clock, priority:5
Note A source listed as “No clock” indicates that no clock source configured at that priority.
Command Purpose
Step1 Switch(config)# interface atm card/subcard/port
Switch(config-if)#
Selects the interface to be configured.
Step2 Switch(config-if)# clock source {free-running |
loop-timed | network-derived}
Configures the interface clock source.
Command Purpose
show network-clocks Shows the network clocking configuration.
more system:running-config Shows the interface clock source configuration.
show controllers [atm card/subcard/port] Shows the interface controller status.