Specifications

CHAPTER

17-1

Cisco MWR 2941 Mobile Wireless Edge Router Release 3.5 Software Configuration Guide, Cisco IOS Release 15.1(3)MR

OL-26895-01

Configuring Synchronous Ethernet ESMC and

SSM

With Ethernet equipment gradually replacing Synchronous Optical Networking (SONET) and

Synchronous Digital Hierarchy (SDH) equipment in service-provider networks, frequency

synchronization is required to provide high-quality clock synchronization over Ethernet ports.

Synchronous Ethernet (SyncE) provides the required synchronization at the physical level. In SyncE,

Ethernet links are synchronized by timing their bit clocks from high-quality, stratum-1-traceable clock

signals in the same manner as SONET/SDH. Operation messages maintain SyncE links, and ensure a

node always derives timing from the most reliable source.

The SyncE synchronizes clock frequency over an Ethernet port. In SONET/SDH the communication

channel for conveying clock information is Synchronization Status Message (SSM), and in SyncE it is

the Ethernet Synchronization Message Channel (ESMC).

Note For information about how to configure synchronous Ethernet, see “Configuring Clocking and Timing”.

Contents

• Prerequisites for Synchronous Ethernet (SyncE): ESMC and SSM, page 17-1

• Restrictions for Synchronous Ethernet (SyncE): ESMC and SSM, page 17-2

• Information About Synchronous Ethernet (SyncE): ESMC and SSM, page 17-2

• How to Configure Synchronous Ethernet (SyncE): ESMC and SSM, page 17-3

• Configuration Examples for Synchronous Ethernet (SyncE): ESMC and SSM, page 17-6

• Additional References, page 17-9

Prerequisites for Synchronous Ethernet (SyncE): ESMC and SSM

You need to first configure the network clock for SyncE configuration. Automatic synchronization of

the network clock should be enabled. Ensure the network-clock-select and network-clock-participate

commands do not exist in the configuration in order to continue with the SyncE configuration.