Simulate a GrandMasterClock (for testing)

Warning: This section is for test only. It is not intended to be used in a real environment.

To avoid the use of a physical grand master clock, a standard machine like a laptop can be used to simulate the PTP reference time. This is called « software PTP ».

To achieve that :

Install linuxptppackage on the laptop.
Configure the PTP settings, in the file /etc/linuxptp/ptp4l.conf
Starts the ptp4lservice.

The configuration of PTP is fixed by IEC-61850 (see here on Wikipedia). Here is a proposed configuration of the file /etc/linuxptp/ptp4l.conf that fits the standard requirements.

[Global]
slaveOnly                0
gmCapable 1

domainNumber             0

# Announce interval: 1s
logAnnounceInterval      0

# Sync interval: 1 s
logSyncInterval          0

# Pdelay interval: 1 s
logMinPdelayReqInterval  0

# Announce receipt time-out: 3 s (fixed)
announceReceiptTimeout   3

priority1                128
priority2                128
# Default clock class : any specialised clock will be better (ie a GPS Grand Master Clock)
#clockClass              192
network_transport        L2
delay_mechanism          P2P
clockClass 248
clockAccuracy 0xFE
offsetScaledLogVariance 0xFFFF

The PTP clock created by ptp4l will not be synchronized with the current time. So even if your cluster machines are synchronized with each other, the date will be random.
To synchronize the PTP clock with the current time, type this command on the machine that simulate the grand master clock

phc_ctl <ptp_interface> set