Frequency Synchronization; Using Synchronous Ethernet For Frequency Synchronization - Cisco NCS 5000 Series Manual

Frequency Synchronization

Frequency Synchronization is used to distribute precision frequency around a network. Frequency is
synchronized accurately using Synchronized Ethernet (SyncE) in devices connected by Ethernet in a network.
This module describes the tasks required to configure frequency synchronization on Cisco IOS XR software.
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Using Synchronous Ethernet for 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 is used that
requires a known, common precision frequency reference at each end of the emulated circuit. The incumbent
example of frequency synchronization is provided by SDH equipment. This is used in conjunction with an
external timing technology to provide precise synchronization across the network.
SDH equipments are widely replaced by Ethernet equipments and synchronized frequency is required over
such Ethernet ports. Synchronized Ethernet (SyncE) is used to accurately synchronize frequency in devices
connected by Ethernet in a network. SyncE provides level frequency distribution of known common precision
frequency references to a physical layer Ethernet network.
To maintain SyncE links, a set of operational messages are required. These messages ensure that a node is
always deriving timing information from the most reliable source and then transfers the timing source quality
information to clock the SyncE link. In SDH networks, these are known as Synchronization Status Messages
(SSMs). SyncE uses Ethernet Synchronization Message Channel (ESMC) to provide transport for SSMs.
SyncE is supported on Cisco NCS 5001 and Cisco NCS 5002 Routers on 100G, 40G, and 10G interfaces in
LAN mode.
Using Synchronous Ethernet for Frequency Synchronization, page 171
Configuring Frequency Synchronization, page 172
Configuring Frequency Synchronization on an Interface, page 174
System Management Configuration Guide for Cisco NCS 5000 Series Routers, IOS XR Release 6.2.x
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