Cisco Systems OL-7396-01 Configuring Network Clocking

3-10
ATM Switch Router Software Configuration Guide
OL-7396-01
Chapter3 Initially Configuring the ATMSwitch Router
Configuring Network Clocking
Configuring Network Clocking
This section describes network clocking configuration of the ATM switch router. Properly synchronized
network clocking is important in the transmission of constant bit rate (CBR) and variable bit rate real
time (VBR-RT) data. For an overview of network clocking and network clock configuration issues, refer
to the chapter “Network Clock Synchronization” in the Guide to ATM Technology.
Network Clocking Features
Different types of network clock sources are available on the ATM switch router, both internal and
external. Ta ble 3-1 provides a summary of network clocking features.
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.
Table3-1 Network Clocking Feature Summary
Platform
Up/Down
Detection
Loss of
Synchronization
Detection
Phase
Adjustment
Cutover
Stratum 3
Clock BITS1 Port
1. BITS = Building Integrated Timing Supply
Clock Source
Preference
Catalyst 8540 MSR
with network clock
module
YesYes YesYesYesBest
Catalyst 8510 MSR Yes Yes Yes No No Medium
LightStream 1010
with FC-PFQ
Yes Yes Yes No No M edi um
Catalyst 8540 MSR
without network
clock module
YesNo NoNoNoPoor
LightStream 1010
without FC-PFQ
YesNo NoNoNoPoor
Command Purpose
network-clock-select {priority {{atm | cbr}
card/subcard/port} | bits {0 | 1} | system} |
bits {e1 | t1} | revertive
Configures the network clock priority.