Hi,

I have lately been doing some tests with linuxptp to use it in a production 
environment. I have set the master server with one terminal window running “# 
ptp4l -i eno1 -m -q -4 -H -P” with the output of “assuming grandmaster role”. I 
have another terminal window on the master server running “# phc2sys -c 
/dev/ptp0 -s CLOCK_REALTIME -w -m -q”. 

On the slave server I have one terminal instance running “# ptp4l -i eno1 -m -q 
-4 -H -P -s” with the output of “port 1: UNCALIBRATED to SLAVE on 
MASTER_CLOCK_SELECTED” stating that synchronisation is successful. 

I have let this setup ran over the weekend starting Friday morning. When I 
check back on Monday to see the values of the master offset the values do 
appear to be acceptable at around 1000 nanoseconds. However, it is constantly 
returning the following messages:

“port 1: received SYNC without timestamp”
“port 1: received PDELAY_RESP without timestamp”
“port 1: received PDELAY_REQ without timestamp”

Every once in a while the process proceeds giving the regular output containing 
the master offset values (which however still appears to return acceptable 
values). After a few minutes of doing so, the message “port 1: received SYNC 
without timestamp” appears 10 times in a row followed by “SLAVE to LISTENING on 
ANNOUNCE_RECEIPT_TIMEOUT_EXPIRES”, followed by the message “port 1: LISTENING 
to UNCALIBRATED on RS_SLAVE” returning a master offset of 758 seconds whereas 
before this occurrence the master offset values were acceptable. Next up it 
immediately returns “UNCALIBRATED to SLAVE on MASTER_CLOCK_SELECTED” returning 
a master offset of 158 seconds and immediately decreasing to the acceptable 
+-1000 nanosecond range within 10 seconds of proceeding the process very normal 
again: no ‘weird’ messages returned, only the “master offset (..)” messages. 

Now since it is proceeding with acceptable values again after some errors, I 
have no idea what errors have occurred during the weekend, making it not a very 
reliable protocol for time alignment. What could be the cause of this 
behaviour, instead of continuously returning the “master offset (..)” message 
as it should do. 

Jord 
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