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[PTP][1588v2] Follow_Up消息

news 来源：原创 2024/5/2 20:06:26

一、报文格式

+0------3--------7--------11--------15--------------------------------31
|TranSpec|MsgType|Reserved1| VerPTP |              MsgLength          |
+----------------|------------------|---------------------------------|
|  DomainNumber  |      Reserved2   |              FlagField          |
+---------------------------------------------------------------------|
|                             CorrectionField                         |
|                                                                     |
+---------------------------------------------------------------------|
|                                Reserved3                            |
+---------------------------------------------------------------------|
|                          SourcePortIdentity                         |
|                                                                     |
|                                   +---------------------------------|
|                                   |         SequenceID              |
+----------------|------------------|---------------------------------|
|  ControlField  |  LogMsgInterval  |                                 |
+---------------------------------------------------------------------|
|                         PreciseOriginTimestamp                      |
|                                                                     |
|                                   |                                 |

字段	长度	含义
TranSpec	4 bits	传送相关。 0–表示PTP消息由1588协议使用 1–表示PTP消息由802.1as协议使用
MsgType	4 bits	0x00: Sync 0x01: Delay_Req
Reserved1	4 bits	保留字段。
VerPTP	4 bits	表示1588协议的版本。
MsgLength	2 bytes	PTP消息的长度，即PTP消息的全部字节数目。计入字节始于报头的第一个字节，同时包含并收尾于任何尾标的最后一个字节，或是无尾标成员时收尾于消息的最后一个字节。
DomainNumber	1 byte	域编号，表示发送该消息时钟所属的域
Reserved2	1 byte	保留字段。
FlagField	2 bytes	标志域。
CorrectionField	CorrectionField	修正域，各报文都有，主要用在Sync报文中，用于补偿网络中的传输时延，E2E的频率同步。
Reserved3	4 bytes	保留字段。
SourcePortIdentity	10 bytes	源端口标识符，发送该消息时钟的ID和端口号。
SequenceID	2 bytes	序列号ID，表示消息的序列号，以及关联消息的对应关系。
ControlField	1 byte	控制域，由消息类型决定。
LogMsgInterval	1 byte	录入消息周期，PTP消息的发送时间间隔
PreciseOriginTimestamp	10 bytes	精确源时间标签。 PTP提供传输时间戳的机制，这个时间戳包括事件消息产生的时刻和相应的修正域，通过这个机制保证接收方接收到的是最精确的时间戳。在实际应用中时间戳分布在：originTimestamp或者preciseOriginstamp和correctionField中，由具体的执行决定。。

二、报文示例

(1) 基于UDP的Follow_Up消息

Frame 1: 90 bytes on wire (720 bits), 90 bytes captured (720 bits)
Ethernet II, Src: 0a:2a:0a:31:0a:13 (0a:2a:0a:31:0a:13), Dst: HuaweiTe_98:f2:6e (00:25:9e:98:f2:6e)
Internet Protocol Version 4, Src: 10.1.1.1 (10.1.1.1), Dst: 224.0.1.129 (224.0.1.129)
User Datagram Protocol, Src Port: ptp-event (319), Dst Port: ptp-general (320)
Precision Time Protocol (IEEE1588)0000 .... = transportSpecific: 0x00...0 .... = V1 Compatibility: False.... 1000 = messageId: Follow_Up Message (0x08).... 0010 = versionPTP: 2messageLength: 44subdomainNumber: 0flags: 0x022c0... .... .... .... = PTP_SECURITY: False.0.. .... .... .... = PTP profile Specific 2: False..0. .... .... .... = PTP profile Specific 1: False.... .0.. .... .... = PTP_UNICAST: False.... ..1. .... .... = PTP_TWO_STEP: True.... ...0 .... .... = PTP_ALTERNATE_MASTER: False.... .... ..1. .... = FREQUENCY_TRACEABLE: True.... .... ...0 .... = TIME_TRACEABLE: False.... .... .... 1... = PTP_TIMESCALE: True.... .... .... .1.. = PTP_UTC_REASONABLE: True.... .... .... ..0. = PTP_LI_59: False.... .... .... ...0 = PTP_LI_61: Falsecorrection: 0.000000 nanosecondscorrection: Ns: 0 nanosecondsSubNs: 0.000000 nanosecondsClockIdentity: 0x00259e1000000001SourcePortID: 1280sequenceId: 5246control: Follow_Up Message (2)logMessagePeriod: -10
preciseOriginTimestamp (seconds): 947131161preciseOriginTimestamp (nanoseconds): 698886823

(2) 基于以太的Follow_Up消息

Frame 1: 64 bytes on wire (512 bits), 64 bytes captured (512 bits)
Ethernet II, Src: HuaweiTe_83:7b:0d (00:25:9e:83:7b:0d), Dst: HuaweiTe_46:8f:7e (00:25:9e:83:7b:0d)Destination: HuaweiTe_46:8f:7e (00:25:9e:83:7b:0d)Source: HuaweiTe_83:7b:0d (00:25:9e:83:7b:0d)Type: PTPv2 OVER eTHERNET (IEEE1588) (0x88f7)
Precision Time Protocol (IEEE1588)0000 .... = transportSpecific: 0x00...0 .... = 802.1as conform: False.... 1000 = messageId: Follow_Up Message (0x08).... 0010 = versionPTP: 2messageLength: 44subdomainNumber: 0flags: 0x022c0... .... .... .... = PTP_SECURITY: False.0.. .... .... .... = PTP profile Specific 2: False..0. .... .... .... = PTP profile Specific 1: False.... .0.. .... .... = PTP_UNICAST: True.... ..1. .... .... = PTP_TWO_STEP: True.... ...0 .... .... = PTP_ALTERNATE_MASTER: False.... .... ..1. .... = FREQUENCY_TRACEABLE: True.... .... ...0 .... = TIME_TRACEABLE: False.... .... .... 1... = PTP_TIMESCALE: True.... .... .... .1.. = PTP_UTC_REASONABLE: False.... .... .... ..0. = PTP_LI_59: False.... .... .... ...0 = PTP_LI_61: Falsecorrection: 0.000000 nanosecondscorrection: Ns: 0 nanosecondsSubNs: 0.000000 nanosecondsClockIdentity: 0x00aa12fffe431112SourcePortID: 1024sequenceId: 12243control: Follow_Up Message (2)
preciseOriginTimestamp (seconds): 946878901preciseOriginTimestamp (nanoseconds): 214732091