Is there a way to know why some gPTP packets are discarded?

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I have a Summit X670 switch with the AVB package installed. When I look at the counters for a specific port with the command : show network-clock gptp counters, the stats indicate some discarded packets. Is there a command or a log that I can use to know the reason why these packets have been discarded?

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Posted 2 years ago

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Chad Smith, Alum

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As far as I know there isn't a show command or log message that will indicate exactly why the packet was discarded.  In the "show network-clock gptp port PORT_NUMBER counters" output there are three counters at the bottom "Announce Receipt Timeout Count", "Sync Receipt Timeout Count", and "Peer Delay Allowed Lost Response Exceeded Count".  I believe each of these errors will also result in a gPTP packet discard.  However, I am not certain if those are the only reasons.  Commonly it is because of an issue with the peer delay measurement.  The example below is from a port that has gPTP enabled, but is connected to a non gPTP capable device:

L3L_K2_U32(65.24).6 # show network-clock gptp port 2 counters
Port number : 2
gPTP port status : Enabled
Parameter Receive Transmit
Announce 0 0
Sync 0 0
Follow Up 0 0
Peer Delay Request 0 172
Peer Delay Response 0 0
Peer Delay Response Follow Up 0 0
gPTP packet discards 172 -
Announce Receipt Timeout Count : 0
Sync Receipt Timeout Count : 0
Peer Delay Allowed Lost Response Exceeded Count : 172

As you can see, the discard counter directly matches the Peer Delay Allowed Response Exceeded Count.
Thanks for the answer