IEEE 1588 PTP Clock Modes and Transports

IEEE 1588 PTP Clock Modes and Transports

IEEE-1588 PTPv2 has various clock-modes that can work with different Transport-layer technologies like Ethernet, IPv4, IPv6 as well as MPLS, DeviceNet, ControlNet, etc. Here we look at the various scenarios and cases on how PTP can serve different network use-cases with its different configuration combinations.

Ethernet Mode

S. No. Transport Clock Mode Delay Mechanism Clock Steps
1 Ethernet Boundary End-to-End 1
2 Ethernet Boundary E2E 2
3 Ethernet Boundary Peer-to-Peer 1
4 Ethernet Boundary P2P 2
5 Ethernet Transparent E2E 1
6 Ethernet Transparent E2E 2 (2-step)
7 Ethernet Transparent P2P 1
8 Ethernet Transparent P2P 2
Table 1: IEEE-1588 Clock Modes with Ethernet Transport

The PTP communication in Ethernet mode using the specific Multicast MAC address(es). These come in two varieties, the general Multicast address (01-1B-19-00-00-00) and the reserved Multicast address (01-80-C2-00-00-0E). While the former is used to deliver General (Announce etc) and event (Sync, Delay_Req etc) messages, the latter is specifically used for peer-delay (Pdelay_Req etc) messages.

1588 Sync and Delay Req

Let us look at the PTP messages and then map them to each of the modes and transports tabulated above.

S. No. Message Type Destination MAC Timestamps
1 Sync Event 01-1B-19-00-00-00 T1, T2
2 Follow_Up General 01-1B-19-00-00-00 T2'
3 Delay_Req Event 01-1B-19-00-00-00 * T3
4 Delay_Resp General 01-1B-19-00-00-00 * T4
5 PDelay_Req Event 01-80-C2-00-00-0E T1, T2
6 PDelay_Resp Event 01-80-C2-00-00-0E T3, T4
7 #P_Follow_Up General 01-80-C2-00-00-0E T3'
8 Announce General 01-1B-19-00-00-00 NA
9 Management General 01-1B-19-00-00-00 NA
10 Signaling General 01-1B-19-00-00-00 NA
Table 2: PTP Message Types and Destination

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