System information

Chapter 3 Initially Configuring the ATM Switch Router
Configuring Network Clocking
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ATM Switch Router Software Configuration Guide
78-6277-03, Cisco IOS Release 12.0(13)W5(19)
Configuring Network Clock Sources and Priorities (Catalyst 8540 MSR)
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
route processor reference clock (a stratum 4 clock source) or the network clock module (a
stratum 3 clock source), if present.
Systems equipped with the network clock module can derive clocking from a Building Integrated
Timing Supply (BITS) source. To specify the line type attached to the BITS ports on the network clock
module and to assign a priority to a port, use the following commands in global configuration mode:
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
Note This configuration assumes that a full-width module, such as the 4-port OC-12c module,
is being used to derive clocking. If port adapters inserted into carrier modules are used,
the priority 1 and 2 source ports must be on different port adapters.
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
Command Purpose
network-clock-select {priority {{atm | cbr}
card/subcard/port} | bits {0 | 1} | system} |
bits {e1 | t1} | revertive
Configures the network clock priority.
Command Purpose
network-clock-select bits {t1 | e1} Selects the line type. This command applies to
both BITS ports.
network-clock-select priority bits {0 | 1} Selects the priority for a BITS port.