Setup guide

2-15
Cisco 6400 Software Setup Guide
OL-1183-04
Chapter2 Basic NSP Configuration
Network Clocking
Configuring the Transmit Clock Source
By default, the interface uses a network-derived clock source. To modify how an interface derives its
transmit clock, complete the following steps beginning in global configuration mode:
Example
In the following example, ATM interface 4/0/0 is configured to derive its transmit clock from the clock
source received on the same interface:
!
interface atm 4/0/0
clock source loop-timed
!
Configuring Network Clock Priorities and Sources
You can configure multiple network clock sources and assign priority values to each source. The system
uses the highest priority clock source available as the “network-derived” clock source for the transmit
clock.
To configure the network clock priorities and sources, use the following command in global
configuration mode:
Example
In the following example, interface ATM 2/0/0 is configured as the highest priority network clock
source:
!
network-clock-select 1 atm 2/0/0
network-clock-select 2 atm 2/0/1
network-clock-select 3 atm 1/0/0
!
interface atm 1/0/0
clock source network-derived
!
As long as interface ATM 2/0/0 is available, all transmit clocking on ATM 1/0/0 will be derived from
ATM 2/0/0. If the ATM 2/0/0 clock source fails, the system will attempt to use the next highest priority
clock source, which in this case is ATM 2/0/1.
Command Purpose
Step1
Switch(config)# interface atm slot/subslot/port
Selects the interface to be configured.
Step2
Switch(config-if)# clock source {free-running |
loop-timed | network-derived}
Specifies how the interface derives its transmit clock.
Command Purpose
Switch(config)# network-clock-select priority
{system | atm slot/subslot/port}
Configures a network clock priority and source. Priority
1
values range from 1 (highest) to 4 (lowest). System selects
the local oscillator on the NSP.
1. Priorities 1 to 4 initially default to “no clock.” Priority 5 is a pseudo-priority that defaults to “system clock” and is not configurable. If priorities 1 to 4
are not configured, the priority 5 system (NSP) clock is used as the derived clock.