Synchronous Ethernet why do they need need clock in OTN network ?

The ITU-T standard that governs synchronous Ethernet is specified in the G.8262 recommendation, titled "Timing characteristics of synchronous Ethernet equipment slave clock (EEC2)." This standard defines the timing requirements and characteristics for synchronous Ethernet equipment, particularly the slave clocks. Its purpose is to ensure precise timing synchronization within Ethernet networks.

In some of the synchronous networks devices rely on a shared clock reference to effectively coordinate their operations. SyncE guarantees that all devices within an Ethernet network, including switches and routers, adhere to a synchronized timing signal.

SyncE remains important even when an Optical Transport Network (OTN) is used for data transport regulated by ITU-T G.709 standards. While OTN incorporates its own synchronization mechanisms, SyncE is specifically designed to synchronize Ethernet traffic within the OTN network.

SyncE ensures that Ethernet traffic transmitted over the OTN network maintains accurate timing intervals in alignment with ITU-T G.8261 and G.8262 standards. This synchronization is particularly critical for time-sensitive applications such as voice and video communication, financial transactions, and real-time services.

By achieving synchronization, SyncE mitigates issues like packet loss, delays, and collisions that can arise when devices operate with unsynchronized clocks. It promotes network stability, reliability, and optimized Quality of Service (QoS) by minimizing timing discrepancies among devices.

When comparing SyncE to typical Ethernet traffic like CBRLan100 (an encapsulation mode used in OTN), it's important to note that CBRLan100 is specifically employed for traffic requiring a constant bit rate. CBRLan100 operates at a different layer in the network, focusing on maintaining a consistent bit rate for transmitted data to ensure a smooth and uninterrupted flow of information. In this context, precise timing synchronization among devices is not necessary.