Versions Compared
compared with
Key
- This line was added.
- This line was removed.
- Formatting was changed.
Latest document version: | ITU-T Recommendation G.8275.1, Amd. 2, 03/201811/2022 (full text publication) | |
---|---|---|
Location: | ||
Objective: | Time distribution to better than ±1.5ms, over a full timing support network |
Feature/ Parameter | Note | Range | Default Value | G.8275.1 Clause | ||
---|---|---|---|---|---|---|
from | to | |||||
Profile Identification | ||||||
profileName: | ITU-T PTP profile for phase/time distribution with full timing support from the network | Annex A.1 | ||||
profileVersion: | 2.4 (IEEE 1588-2008) / 2.15 (IEEE1588-2019) | Annex A.1 | ||||
profileIdentifier: | 00-19-A7-01-02-04 / 00-19-A7-01-02-05 | Annex A.1 | ||||
Specified by: | ITU-T | Annex A.1 | ||||
Location: | www.itu.int | Annex A.1 | ||||
PTP Options | ||||||
Permitted Nodes | Ordinary clocks (i.e. Grandmasters, slave-only clocks), boundary clocks, end-to-end transparent clocks | Annex A.3.1, 6.2.3 | ||||
Prohibited Nodes | Peer-to-peer transparent clocks | Annex A.3.1 | ||||
Transport Mechanisms | Required: IEEE802.3 Ethernet, as per IEEE1588-2008 Annex F. Both multicast addresses noted in IEEE1588-2008 must be supported by all clocks. (i.e. 01-80-C2-00-00-0E non-forwardable and 01-1B-19-00-00-00 forwardable address). The use of VLAN tags is not allowed. Other transport mechanisms (e.g. IP/UDP as in Annexes D & E) are for further study. | Annex A.3.3, 6.2.6, 6.2.7 | ||||
Multicast or Unicast | Full multicast operation, using both of the addresses noted in IEEE1588-2008 Annex F Unicast is not permitted. | Annex A.3.4, 6.2.6 | ||||
BMCA | Alternate BMCA specified (see details below) | Annex A.4, 6.3.1 | ||||
Path Delay Measurement | Uses delay_request/response mechanism. Peer delay mechanism must not be used. | Annex A.5 | ||||
PTP Management | Not specified in this version of the profile. | Annex A.7 | ||||
Clock Identity | EUI-64 (as specified in clause 7.5.2.2.2 of IEEE1588-2008) | Annex A.6 | ||||
Message Types | Used: Announce, Sync, Follow-up, Delay_Req, Delay_Resp Not used: Pdelay_Req, Pdelay_Resp, Pdelay_Resp_Follow_Up The use of Signaling and Management messages is for further study. | 6.2.2 | ||||
One-step and Two-step clock | Clocks may transmit messages using either one-step or two-step modes. Clocks must be capable of receiving and handling messages from both one-step and two-step clocks, without configuration. | Annex A.3.2, 6.2.5 | ||||
One-way and Two-way Operation | Only two-way operation is permitted. | 6.2.4 | ||||
Security | For further study. IEEE1588-2008 Annex K experimental security protocol is not used | Annex A.8, 8 | ||||
Unicast negotiation (IEEE1588-2008 clause 16.1) | Not used. | Annex A.9 | ||||
Path trace (IEEE1588-2008 clause 16.2) | Optional. | Annex D | ||||
Alternate timescales (IEEE1588-2008 clause 16.3) | PTP timescale used. Alternate timescales are not used. | Annex A.9 | ||||
Grandmaster clusters (IEEE1588-2008 clause 17.3) | Not used. | Annex A.9 | ||||
Alternate masters (IEEE1588-2008 clause 17.4) | Not used. | Annex A.9 | ||||
Unicast discovery (IEEE1588-2008 clause 17.5) | Not used. | Annex A.9 | ||||
Acceptable master table (IEEE1588-2008 clause 17.6) | Not used. | Annex A.9 | ||||
Cumulative frequency scale factor offset (IEEE1588-2008 Annex L) | Not used. | Annex A.9 | ||||
Message Rates | ||||||
Sync & Follow-up | 16 per second | 16 | 16 | 6.2.8 | ||
Delay_request/response | 16 per second | 16 | 16 | |||
Announce | 8 per second | 8 | 8 | |||
Peer Delay_request/response | None (uses Delay_request/response mechanism) | |||||
Signaling | Not used | |||||
Management | Not used | |||||
PTP Configurable Attribute Values(all others as per PTP, defined in IEEE1588-2008) | ||||||
Default data set | ||||||
twoStepFlag | Used as per PTP, according to clock's capability | FALSE | TRUE | 6.2.5, Table A.1 | ||
clockIdentity | Based on EUI64 format, as per PTP | Table A.1, Annex A.7 | ||||
numberPorts | Always 1 for ordinary clocks (Grandmasters, slaves) | Ordinary clocks | 1 | 1 | Table A.1 | |
As required for Boundary or Transparent clocks | Boundary, Transparent Clocks | 1 | N | |||
clockQuality.clockClass | Grandmaster clocks | 6, 7, 140, 150, 160, 248 | 248 | Table A.1, 6.4 (Table 2) | ||
Boundary clocks | 135, 165, 248 | 248 | ||||
Slave-only clocks | 255 | 255 | ||||
clockQuality.clockAccuracy | Grandmaster clocks traceable to a GNSS-locked ePRTC | 0x20 | 0xFE | Table A.1, 6.3.5 | ||
Grandmaster clocks traceable to a GNSS-locked PRTC | 0x21 | |||||
Grandmaster clocks not traceable to a PRTC | 0xFE | |||||
Boundary clocks and slave-only clocks | 0xFE | |||||
clockQuality. offsetScaledLogVariance | Grandmaster clocks traceable to a GNSS-locked ePRTC | 0x4B32 | 0xFFFF | |||
Grandmaster clocks traceable to a GNSS-locked PRTC | 0x4E5D | |||||
Grandmaster clocks not traceable to a PRTC | 0xFFFF | |||||
Boundary clocks and slave-only clocks | 0xFFFF | |||||
priority1 | All clock types | 128 | 128 | Table A.1, 6.3.3 | ||
priority2 | Use cases to aid network topology establishment and configure protection paths described in Appendices IV and X | Grandmasters, boundary clocks | 0 | 255 | 128 | Table A.1, 6.3.4 |
Slave-only clocks | 255 | 255 | ||||
domainNumber | All clock types | 24 | 43 | 24 | Table A.1 6.2.1 | |
slaveOnly | Grandmasters and boundary clocks | FALSE | FALSE | Table A.1 | ||
Slave-only clocks | TRUE | TRUE | ||||
Profile-specific defaultDS attributes | ||||||
localPriority | New dataset member defined in profile Allows operators to manually configure the topology of the synchronization network (see Annex B) | 1 | 255 | 128 | Table A.1, 6.3.2 | |
maxStepsRemoved | New dataset member defined in profile Allows operators to configure the maximum distance between a T-GM and a T-TSC | 1 | 255 | 255 | Table A.1, Annex F | |
Port data set (configurable members) | ||||||
portIdentity.clockIdentity | Based on EUI64 format, as per PTP | Table A.5 | ||||
portIdentity.portNumber | Always 1 for ordinary clocks Boundary and transparent clocks as required for device | Ordinary clocks | 1 | 1 | Table A.5 | |
Boundary, Transparent clocks | 1 | N | ||||
logMinDelayReqInterval | Delay_Req message rate: | 16 messages/second | -4 | -4 | Table A.5 | |
logAnnounceInterval | Announce message rate: | 8 messages/second | -3 | -3 | Table A.5 | |
announceReceiptTimeout | Timeout period before declaring loss of announce service: | 3 missing messages | 3 | FFS | 3 | Table A.5 |
logSyncInterval | Sync message rate: | 16 messages/second | -4 | -4 | Table A.5 | |
delayMechanism | Uses end-to-end delay mechanism | 1 | 1 | Table A.5 | ||
logMinPdelayReqInterval | Pdelay message rate: not used in this profile | Table A.5 | ||||
versionNumber | PTP protocol version number: Version 2 only | 2 | 2 | Table A.5 | ||
Profile-specific portDS attributes | ||||||
masterOnly | New dataset member defined in profile. Renamed from notSlave | Grandmaster clocks | TRUE | TRUE | Table A.5, 6.3.1 | |
Boundary clocks | FALSE | TRUE | TRUE | |||
Slave clocks | FALSE | FALSE | ||||
localPriority | New dataset member defined in profile Allows operators to manually configure the topology of the synchronization network | 1 | 255 | 128 | Table A.5, 6.3.2 | |
PTP common message header flags | ||||||
alternateMasterFlag | Set FALSE on transmission; used as per PTP by receiving nodes | FALSE | FALSE | Table A.8 | ||
twoStepFlag | Used as per PTP defined in IEEE1588-2008 | FALSE | TRUE | |||
unicastFlag | Set FALSE on transmission; ignored on reception. | FALSE | FALSE | |||
PTP profile Specific1 | Set FALSE on transmission; ignored on reception. | FALSE | FALSE | |||
PTP profile Specific2 | Set FALSE on transmission; ignored on reception. | FALSE | FALSE | |||
Reserved | Set FALSE on transmission; ignored on reception. | FALSE | FALSE | |||
leap61 | Used as per PTP defined in IEEE1588-2008 | FALSE | TRUE | |||
leap59 | Used as per PTP defined in IEEE1588-2008 | FALSE | TRUE | |||
currentUTCOffsetValid | Used as per PTP defined in IEEE1588-2008 | FALSE | TRUE | |||
ptpTimescale | Set TRUE on transmission. | TRUE | TRUE | |||
timeTraceable | Used as defined in Table 2 of G.8275.1 | FALSE | TRUE | Table A.8, Table 2 | ||
frequencyTraceable | Used as defined in Table 2 of G.8275.1 | FALSE | TRUE | |||
controlField | Not used; ignored on reception. | 6.3.8 | ||||
Profile-specific common message header flags | ||||||
synchronizationUncertain | Profile specific optional flag in octet 1, bit 6, indicating that the source of synchronization is uncertain (e.g. clock is in UNCALIBRATED state while switching to a new T-GM). | FALSE | TRUE | FALSE | Table A.8, Annex E | |
Unicast and Multicast Operation | ||||||
Full multicast operation | Fully multicast operation | Annex A.3.4 | ||||
Full unicast operation | Not used. | |||||
Hybrid unicast/multicast | Not used. | |||||
Unicast negotiation process | Not used. | |||||
Best Master Clock Algorithm (BMCA) | ||||||
BMCA type: | Alternate BMCA (modified default BMCA) | 6.3.1 | ||||
State decision algorithm | Based on default state decision algorithm, adding check for new parameter masterOnly | 6.3.6 | ||||
Data set comparison algorithm | Based on default data set comparison with following changes: - moves check on GM clockIdentity to end - removes check on GM priority1 values - adds check for new parameter localPriority value (after GM priority2) | 6.3.7 |
On this page:
Table of Contents |
---|