Cisco ASR 9000 Series User Manual

CHAPTER 10
Configuring Frequency Synchronization
Frequency Synchronization is used to distribute precision frequency around a network. This module describes
the tasks required to configure frequency synchronization on the Cisco IOS XR software.
For more information about frequency synchronization on the Cisco IOS XR software and complete
descriptions of the commands listed in this module, see Additional References. To locate documentation for
other commands that might appear in the course of running a configuration task, search online in
Cisco ASR 9000 Series Aggregation Services Router Commands Master List.
Table 24: Feature History for Implementing Frequency Synchronization on Cisco IOS XR Software
ModificationRelease
This feature was introduced.Release 3.9.0
Support introduced for nV Cluster Clocking.Release 5.3.0
This module contains the following topics:
•
Information About Frequency Synchronization, page 191
•
Configuring Frequency Synchronization, page 193
Information About Frequency Synchronization
Frequency or timing synchronization is the ability to distribute precision frequency around a network. In this
context, timing refers to precision frequency, not an accurate time of day. Precision frequency is required in
next generation networks for applications such as circuit emulation. To achieve compliance to ITU specifications
for TDM, differential method circuit emulation must be used, which requires a known, common precision
frequency reference at each end of the emulated circuit.
The incumbent example of frequency synchronization is provided by SDH and SONET equipment. This is
used in conjunction with an external timing technology (such as Cesium oscillators or GPS) to provide
synchronization of precision timing across the network. As, increasingly, SDH and SONET equipment is
replaced by Ethernet equipment this frequency synchronization ability is required over Ethernet ports.
Cisco ASR 9000 Series Aggregation Services Router System Management Configuration Guide, Release 5.1.x
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Cisco ASR 9000 Series Specifications

General

Brand	Cisco
Model	ASR 9000 Series
Category	Network Router
Language	English