Ptp Process; High Availability For Ptp - Cisco Nexus 3548 series Configuration Manual
Nx-os system management, release 7.x
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Also See for Nexus 3548 series:
- Command reference manual (556 pages) ,
- Configuration manual (220 pages) ,
- Installation manual (112 pages)
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Configuring PTP
Note
PTP operates only in boundary clock mode. We recommend that you deploy a Grand Master Clock (10 MHz)
upstream. The servers contain clocks that require synchronization and are connected to the switch.
End-to-end transparent clock and peer-to-peer transparent clock modes are not supported.
PTP Process
The PTP process consists of two phases: establishing the master-slave hierarchy and synchronizing the clocks.
Within a PTP domain, each port of an ordinary or boundary clock follows this process to determine its state:
• Examines the contents of all received announce messages (issued by ports in the master state)
• Compares the data sets of the foreign master (in the announce message) and the local clock for priority,
• Determines its own state as either master or slave
After the master-slave hierarchy has been established, the clocks are synchronized as follows:
• The master sends a synchronization message to the slave and notes the time it was sent.
• The slave receives the synchronization message and notes the time that it was received. For every
• The slave sends a delay-request message to the master and notes the time it was sent.
• The master receives the delay-request message and notes the time it was received.
• The master sends a delay-response message to the slave. The number of delay request messages should
• The slave uses these timestamps to adjust its clock to the time of its master.
High Availability for PTP
Stateful restarts are not supported for PTP
Peer-to-peer transparent clock
Measures the residence time of a PTP message and computes the link delay between each port and
a similarly equipped port on another node that shares the link. For a packet, this incoming link delay
is added to the residence time in the correction field of the PTP message or an associated follow-up
message.
clock class, accuracy, and so on
synchronization message, there is a follow-up message. The number of sync messages should be equal
to the number of follow-up messages.
be equal to the number of delay response messages.
Cisco Nexus 3548 Switch NX-OS System Management Configuration Guide, Release 7.x
PTP Process
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