Which synchronization solution uses the Ethernet physical layer while another is packet-based?

The synchronization solution that uses the Ethernet physical layer is SyncE (Synchronous Ethernet). SyncE extends the synchronization capabilities of Ethernet networks by using the physical layer to maintain clock synchronization across the network. This is achieved by carrying frequency synchronization information along the same lines as the data transmission, ensuring that the timing is maintained as closely as possible to the original source. It is primarily designed to work with existing Ethernet equipment, enabling accurate timing without requiring significant changes to the network infrastructure.

In contrast, while PTP (Precision Time Protocol) and IEEE 1588 refer to protocols that also aim to synchronize clocks within packet-switched networks, they operate at a higher layer and are not tied directly to the physical layer like SyncE. Additionally, VLANs (Virtual Local Area Networks) are used for network segmentation and do not pertain to synchronization. Therefore, SyncE stands out as the synchronization method that utilizes the characteristics of the Ethernet physical layer while ensuring precision timing is maintained across the network infrastructure.