PTP

Precision Time Protocol

• PTP provides nanosecond-level accuracy using hardware timestamping.
• PTP requires dedicated, PTP-aware (IEEE 1588) switches and a local Grandmaster clock.

Configuration

1. Set the synchronization clock

Router(config)# ptp {mode {boundary | e2etransparent | forward} | priority1 VALUE | priority2 VALUE}
                                                                           128/0-255         128/0-255

The priority are for best master clock selection. Lower values take precedence.

Modes	Description
boundary	Enable the switch to participate in selecting the best master clock. If no better clocks are detected, the switch becomes the grandmaster clock on the network and the parent clock to all connected devices. If the best master is determined to be a clock connected to the switch, the switch synchronizes to that clock as a child to the clock, then acts as a parent clock to devices connected to other ports.
e2etransparent	Also known as end-to-end transparent mode, for the switch to synchronize all switch ports with the grand master clock connected to the switch. This is the default clock mode.
forward	For incoming PTP packets to pass through the switch as normal multicast traffic. This disables both boundary and end-to-end transparent mode.

2. Specify the settings for the timing messages. These options are only available when the switch is in boundary mode.

Router(config)# interface INTERFACE-ID
Router(config-if)# ptp {announce {interval VALUE | timeout VALUE} | delay-req interval VALUE | enable | sync {interval VALUE | limit VALUE}}

Settings	Description	Values
announce interval	Time for sending announce messages	0 to 4 seconds; default is 1 (2 seconds)
announce timeout	Time for announcing timeout messages	2 to 10 seconds; default is 3 (8 seconds)
delay request interval	Time recommended to the member devices to send delay request messages when the port is in the master state	–1 to 6 seconds; default is 5 (32 seconds)
sync interval	Time for sending synchronization messages	–1 to 1 second; default is 1 second
sync limit	Maximum clock offset value before PTP attempts to resynchronize	50 to 500000000 nanoseconds; default is 50000 nanoseconds