IEC 61588:2021定义了一种网络协议，即精确时间协议（PTP），该协议能够实现网络化分布式系统中设备实时时钟的精确同步。该协议适用于设备通过网络（包括以太网）进行通信的系统。该标准允许多播通信、单播通信或两者兼有。该标准规定了将协议映射到特定网络实现的要求，并定义了此类映射，包括用户数据报协议（UDP）/互联网协议（IP版本4和6）以及第二层IEEE 802.3以太网。

IEC 61588:2021 defines a network protocol, the Precision Time Protocol (PTP), enabling accurate and precise synchronization of the real-time clocks of devices in networked distributed systems. The protocol is applicable to systems where devices communicate via networks, including Ethernet. The standard allows multicast communication, unicast communication or both. The standard specifies requirements for mapping the protocol to specific network implementations and defines such mappings, including User Datagram Protocol (UDP)/Internet Protocol (IP versions 4 and 6), and layer-2 IEEE 802.3 Ethernet.