Frequency synchronization can be distributed via Synchronous Ethernet. Please select true statement for SynchE.

Synchronous Ethernet (SynchE) is a physical layer (Layer 1) technology for distributing frequency synchronization in a hop-by-hop manner. A network element receives a synchronized signal on an input port, recovers the clock from the physical layer bitstream, and then uses this recovered clock to time the transmission on its output ports. For the synchronization chain to remain intact from the primary reference clock (PRC) to the end device, every single intermediate network element (e.g., switch, router) along the path must support and be configured for SynchE. If any node in the path does not support SynchE, it will break the synchronization chain.

A. SynchE is a physical layer (Layer 1) technology that recovers timing from the bitstream, not a data link layer (Layer 2) protocol.
B. The stability of the recovered frequency is independent of network load, as the physical layer clock rate is constant regardless of traffic volume.
D. SynchE is a standard specifically for Ethernet networks. Optical Transport Network (OTN) is a different technology with its own distinct synchronization mechanisms.

1. International Telecommunication Union (ITU-T). (2015). G.8264: Distribution of timing information through packet networks.

Section 6.1, "Synchronous Ethernet architecture," states: "The frequency is transferred hop-by-hop over the physical layer. The SyncE network is composed of a chain of Ethernet switches." This confirms the hop-by-hop requirement, directly supporting answer C.

2. International Telecommunication Union (ITU-T). (2018). G.8262: Timing characteristics of a synchronous Ethernet equipment slave clock.

Section 1, "Scope," specifies: "Synchronous Ethernet (SyncE) is a technology that allows the transfer of frequency at the physical layer of Ethernet." This directly refutes option A, clarifying that SynchE is a Layer 1 technology.

3. Nokia. (2021). 7750 SR OS System Management Guide, Release 21.10.R1.

Chapter: System Synchronization, Section: Synchronous Ethernet, explains: "Synchronous Ethernet is a physical layer technology that functions on a hop-by-hop basis... The frequency is transported from node to node within the Ethernet physical layer." This official vendor documentation confirms that SynchE is a Layer 1, hop-by-hop mechanism, supporting the correctness of C and incorrectness of A.