System information

Chapter 3 Initially Configuring the ATM Switch Router
Configuring Network Clocking
3-12
ATM Switch Router Software Configuration Guide
78-6277-03, Cisco IOS Release 12.0(13)W5(19)
Configuring Network Clock Sources and Priorities (Catalyst 8510 MSR and
LightStream 1010)
To configure the network clocking priorities and sources, use the following command in global
configuration mode:
Note Specifying the keyword system with the network-clock-select command selects the
processor card reference clock (a stratum 4 clock source).
Examples
The following example shows how to configure the network clock priorities:
Switch(config)# network-clock-select 1 atm 0/0/0
Switch(config)# network-clock-select 2 atm 0/0/3
The following example shows how to configure the network clock to revert to the highest priority clock
source after a failure and takeover by the source with the next lowest priority.
Switch(config)# network-clock-select revertive
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, which
could cause a clocking loop to be formed on a link. See the “Configuring Network
Clocking with NCDP” section on page 3-14.
Command Purpose
network-clock-select {priority {{atm | cbr}
card/subcard/port} | system} | revertive
Configures the network clock priority.
Command Purpose
Step 1
Switch(config)# interface atm card/subcard/port
Switch(config-if)#
Selects the interface to be configured.
Step 2
Switch(config-if)# clock source {free-running |
loop-timed | network-derived}
Configures the interface clock source.