Title: Timing and synchronization aspects in packet networks

On this page:

Summary

• Defines ESMC (Ethernet Synchronization Message Channel) to carry SSM messages

• Defines functional models for SyncE and Circuit Emulation synchronization

Status

• Current version: 3rd. Edition, August 2017, plus Amendment 1, March 2018

• Download from: http://www.itu.int/ITU-T/recommendations/rec.aspx?rec=13321

Key Contents

• Definition of ESMC:

  • ESMC based on Ethernet Link OAM using the Organizational Specific Slow Protocol (OSSP)

  • Carries 4-bit SSM code defining Quality Level (QL) (codes defined in G.781)

  • “Heart-beat” frame sent once per second

  • Event frame sent on QL-change

  • Link declared down after 5s without receiving a heartbeat frame

• Use of SyncE in a multi-operator context

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