This article provides a general introduction to Precision Time Protocol (PTP) supported within EOS. PTP is aimed at distributing time with sub-microsecond accuracy. PTP support is based on the IEEE-1588 specification for version 2 of the protocol. 

This TOI document describes the supported Precision Time Protocol (PTP) functionality on the CCS-750X platforms. Due to the nature of the hardware for these products, the supported PTP functionality and interoperation with other features may differ from other Arista products.

Precision Time Protocol (PTP) management messages are general messages sent to PTP-enabled switches on the data plane. On Arista switches, its behavior depends on the configured PTP mode. 

This article describes the usage of the ptp free-running source clock command, which selects a time source used by a switch running the Precision Time Protocol (PTP) while it is in a free-running state.