In a PTP network, multiple clocks may be capable of serving as the primary source of time. The Best Master Clock Algorithm (MBCA) to select the single best clock to become the single active Grandmaster (GM) for the PTP domain. Typically, the list specifies the MAC addresses or EUI-64 bit number of clocks on the network.

To delete the GM clocks list, use the no version of the command to delete the GM list. If no list exists, EOS considers all potential GM clocks by default.

To add the MAC addresses, 00:00:79:ff:ff:01:00:00 through 00:00:79:ff:ff:03:00:00, use the following commands:

switch(config)# ptp grandmasters
switch(config-ptp-grandmasters)# clock-identity accepted 00:00:79:ff:ff:01:00:00
switch(config-ptp-grandmasters)# clock-identity accepted 00:00:79:ff:ff:02:00:00
switch(config-ptp-grandmasters)# clock-identity accepted 00:00:79:ff:ff:03:00:00

To delete a clock from the acceptable grandmaster list, use the following commands:

switch(config)# ptp grandmasters
switch(config-ptp-grandmasters)# no clock-identity accepted 00:00:79:ff:ff:01:00:00

To delete the entire list, use the no version of the command:

switch(config)# no ptp grandmasters

switch# show ptp interface ethernet4 counters drop
   Endpoint       Dir       Reason                                                   Count                  Last Seen
-------------- --------- -------------------------------------------------------- ----------- -----------------------
   Et4            rx        Announce message with less than foreign master               1    2025-10-01 UTC 02:59:05
                            threshold value.
   Et4            rx        Announce message with non-accepted grandmaster                  32     2025-10-01 UTC 03:00:17
                            clock identity.
   Et4            rx        Follow up message with received port is not slave.          60    2025-10-01 UTC 03:00:18
   Et4            rx        Sync message with received port is not slave.               60    2025-10-01 UTC 03:00:18