PTP Ethernet Capabilities

The 7705 SAR can be configured to transmit and receive PTP messages over a port that uses Ethernet encapsulation. The encapsulation type can be null, dot1q, or qinq. Ethernet-encapsulated PTP messages are processed on the node CSM or CSM functional block, and they are supported on ordinary slave, ordinary master, or boundary clocks for either frequency or time of day/phase recovery. The 7705 SAR-Ax can also support a grand master clock. The 7705 SAR-H, 7705 SAR-Wx, 7705 SAR-8 Shelf V2, and 7705 SAR-18 can also support a grand master clock when equipped to support GNSS. A PTP clock using Ethernet encapsulation can support up to 50 external peer clocks.

All platforms and cards that support PTP functionality support Ethernet-encapsulated PTP messages, except for the 2-port 10GigE (Ethernet) Adapter card/module . See Table: IEEE 1588v2 PTP Support per Fixed Platform and Table: IEEE 1588v2 PTP Support per Card on the 7705 SAR-8 Shelf V2 and 7705 SAR-18 for a complete list of supported platforms and cards.

Ethernet encapsulation is configured on a -port basis using the config>system> ptp>clock command, with the clock-id parameter set to csm. Ports can simultaneously support IPv4-encapsulated or IPv6-encapsulated PTP messages and Ethernet-encapsulated PTP messages. As well, the 7705 SAR supports the interworking of a PTP slave using IPv4-encapsulated or IPv6-encapsulated messages with a PTP master using Ethernet-encapsulated messages.

When a PTP clock is configured for Ethernet encapsulation, the following profiles are available:

• ieee1588-2008

• g8275dot1-2014

• iec-61850-9-3-2016

• c37dot238-2017

Table: Rates for Ethernet-Encapsulated PTP Messages describes the supported message rates for slave and master states for Ethernet-encapsulated PTP traffic, based on the profile configured. The ordinary clock can be either in the slave or master state. The boundary clock can be in both of these states.

See Table: Rates for IP-Encapsulated PTP Messages for the supported message rates for IP-encapsulated PTP traffic.

PTP messages are transported within Ethernet frames with the Ethertype set to 0X88F7. Ports can be configured with one of two reserved multicast destination addresses:

• 01-1B-19-00-00-00 — used for all PTP messages except for peer delay mechanism messages

• 01-80-C2-00-00-0E — used for peer delay mechanism messages

Either address can be used for all messages depending on customer requirements. See Recommendation ITU-T G.8275.1/Y.1369.1. When the profile configuration is iec-61850-9-3-2016 or c37dot238-2017, the 01-80-C2-00-00-0E address must be used for peer delay. See IEC/IEEE 61850-9-3 and the C37.238-2017 extension.

When the profile configuration is ieee1588-2008, iec-61850-9-3-2016, or c37dot238-2017, the PTP clock’s priority1 and priority2 settings are used by the BMCA to help determine which clock should provide timing for the network. When the profile configuration is g8275dot1-2014, the local-priority value is used to choose between PTP masters in the BMCA.