This appendix discusses the field definitions for IEEE 1588 messages. In all cases, the fields are marshalled into their on-the-wire format in the order given in the tables.
The fields common to all PTP messages are defined in Clause 8.2 [24]. These fields and their purposes are shown in Table A.1.
| Field name | Purpose |
|---|---|
| versionPTP | The version of the standard |
| versionNetwork | The version of the relevant network annex |
| subdomain | The application subdomain of the protocol |
| messageType | Identifies message as event or general |
| sourceCommunicationTechnology | First element in unique source identification |
| sourceUuid | Second element in unique source identification |
| sourcePortld | Third element in unique source identification |
| sequenceld | The counter associated with the message |
| control | Indicates the message type, e.g., Sync |
| flags | Message source or contents configuration |
| reserved | Reserved for future use |
The fields of PTP Sync and Delay_Req messages are defined in Clause 8.3 [24]. These fields and their purposes are shown in Table A.2. The common fields from Table A.1 are not repeated in Table A.2.
| Field name | Purpose |
|---|---|
| common | Fields in Table A.1 |
| originTimestamp | Estimated sending time of message |
| epochNumber | Epoch portion of the time scale |
| currentUTCOffset | Difference between UTC and TAI |
| grandmasterCommunicationTechnology | Used by best master clock algorithm |
| grandmasterClockUuid | Used by best master clock algorithm |
| grandmasterPortId |
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