System Management Configuration Guide, Cisco Catalyst IE3x00 Rugged, IE3400 Heavy Duty, and ESS3300 Series Switches

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System Management Configuration Guide, Cisco Catalyst IE3x00 Rugged, IE3400 Heavy Duty, and ESS3300 Series Switches

Configure NTP to PTP time conversion

Updated: June 26, 2026

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Configure NTP to PTP time conversion to enable the switch to use Network Time Protocol as a time source for Precision Time Protocol synchronization.

This task configures NTP to PTP time conversion to enable the switch to use Network Time Protocol as a time source for Precision Time Protocol synchronization.

Note

Beginning with the Cisco IOS XE Dublin 17.12.x release, Cisco Catalyst IE3100 Rugged Series Switches are supported for NTP to PTP time conversion.

Before you begin

  • Review the PTP configuration and mode limitations.

  • To use the NTP to PTP conversion feature, the switch must have an IP address for NTP to function.

  • To use the NTP to PTP conversion feature, configure at least one NTP server. If you configure three or more NTP servers, NTP can ignore inaccurate clocks.

    Note

    For information about configuring NTP, see Network Time Protocol

  • When you enter no with PTP port configuration commands, the specified port property is set to the default value.

  • To determine the value in seconds for the PTP global command interval variable, use a logarithmic scale. These examples show the interval variable value converted to seconds using a logarithmic scale:

Value Entered

Logarithmic Calculation

Value in Seconds

-1

2 -1

1/2

0

2 0

1

Follow these steps to configure NTP to PTP time conversion:

Procedure

1.

Use the configure terminal command to enter global configuration mode.

Example:

Device# configure terminal
2.

Use the ptp profile power command to configure Power Profile mode.

Example:

Device(config)# ptp profile power
Note

no ptp profile power configures Default Profile mode.
3.

Use the ptp mode gmc-bc delay-req command to specify GMC-BC as the synchronization clock.

Example:

Device(config)# ptp mode gmc-bc delay-req

The GMC-BC automatically selects NTP as the time source if it is available.
4.

(Optional) Use the ptp priority1 priority priority2 priority command to specify the BMCA priority.

Example:

Device(config)# ptp priority1 100 priority2 100

  • priority1 priority— Overrides the default criteria (such as clock quality and clock class) for the most accurate time source clock selection.

  • priority2 priority— Breaks the tie between two switches that match the default criteria. For example, enter 2 to give a switch priority over identical switches.

  • priority — A priority number from 0 to 255. The default is 128.

Note

A lower value has higher priority.
5.

(Optional) Use the ptp transfer {feedforward | filter {adaptive | linear}} command to specify the BC synchronization algorithm.

Example:

Device(config)# ptp transfer feedforward

  • feedforward —Very fast and accurate. No PDV filtering.

  • filter adaptive —Automatically filters as much PDV as possible.

  • filter linear —Provides a simple linear filter (default).
6.

Use the interface interface-id command to enter interface configuration mode.

Example:

Device(config)# interface gigabitethernet 1/0/1
7.

(Optional) Use the ptp command to specify port settings.

Example:

Device(config-if)# ptp enable

ptp {announce {interval value | timeout value } | delay-req interval value | enable | sync {interval value | limit value } | vlan value }

  • announce interval value —Sets the logarithmic mean interval in seconds to send announce messages. The range is 0 to 4. The default is 1 (2 seconds).

  • announce timeout value — Sets the time to announce timeout messages. The range is 2 to 10 seconds. The default is 3 (8 seconds).

  • delay-req interval value —Sets the logarithmic mean interval in seconds for time recipient devices to send delay request messages when the port is in the time source clock state. The range is -2 to 6. The default is -5 (1 packet every 1/32 seconds, or 32 packets per second).

  • enable —Enables PTP on the port base module.

  • sync interval value —Sets the logarithmic mean interval in seconds to send synchronization messages. The range is –2 to 1. The default is 1 second.

  • sync limit value —Sets the maximum clock offset value before PTP attempts to resynchronize. The range is from 50 to 500000000 nanoseconds. The default is 500000000 nanoseconds.

  • vlan value —Sets the PTP VLAN on a trunk port. The range is from 1 to 4094. The default is the native VLAN of the trunk port. In boundary mode, only PTP packets in PTP VLAN will be processed, PTP packets from other VLANs will be dropped. Before configuring the PTP VLAN on an interface, the PTP VLAN must be created and allowed on the trunk port.
8.

Use the end command to return to privileged EXEC mode.

Example:

Device(config-if)# end

The switch is configured with NTP to PTP time conversion. The system can now use NTP as a time source for PTP synchronization when operating as a Grandmaster Clock with Boundary Clock functionality.

The example configuration shows the switch using the Default Profile, acting as Grandmaster Clock with NTP as the time source, and using the feedforward BC synchronization algorithm:

Device(config)# ptp mode gmc-bc delay-req
Device(config)# ptp transfer feedforward

Verify configuration

Verify that the switch is running as GMC-BC and that NTP and PTP are synchronized.

Monitor NTP status

Monitor the NTP status until it locks.

show ntp status

ay special attention to these fields.

  • Clock is synchronized/unsynchronized.

  • System poll interval—how often the NTP client sends messages in seconds.

  • Last update—how many seconds since the last clock adjustment.

Switch# show ntp status
Clock is synchronized, stratum 2, reference is 72.163.32.43
nominal freq is 286.1023 Hz, actual freq is 286.0738 Hz, precision is 2**21
ntp uptime is 58682700 (1/100 of seconds), resolution is 3496
reference time is D95162A8.68E52FF9 (22:52:24.409 UTC Wed Jul 15 2015)
clock offset is 0.0459 msec, root delay is 16.19 msec
root dispersion is 15.07 msec, peer dispersion is 0.10 msec
loopfilter state is 'CTRL' (Normal Controlled Loop), drift is 0.000099341 s/s
system poll interval is 1024, last update was 925 sec ago.

Display NTP server status

Display the status of each NTP server:

show ntp association

  • The sys.peer is the currently selected reference.

  • Candidates are fallback references.

  • Falsetickers are bad clocks that are ignored.

Note

There is a delay of several seconds from NTP picking an association to NTP declaring lock.

Wwitch# show ntp association
address         ref clock       st   when   poll reach  delay  offset   disp
+~171.68.38.65    .GPS.            1    706   1024   377 60.318  -0.255  0.166
+~171.68.38.66    .GPS.            1    450   1024   377 60.333  -0.096  0.121
-~10.81.254.202   .GPS.            1    555   1024   377 48.707   2.804  0.111
x~173.38.201.115  .GPS.            1    322   1024   377 293.19  74.409  0.107
*~72.163.32.43    .GPS.            1     37   1024   375 17.110  -0.410  0.081
 * sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured

Verify NTP and PTP clock synchronization

After NTP is running, verify that the NTP clock and the PTP clock are synchronized.

  • show clock detail shows the NTP time.

  • show PTP clock shows the PTP time and the BMCA dataset details.

  • show PTP clock Steps Removed field indicates whether the GMC-BC really is the GMC or if some other clock is running the PTP network. When the GMC wins the BMCA, the Steps Removed field should be 0.

show clock detail
23:16:53.865 UTC Wed Jul 15 2015
Time source is NTP
show ptp clock
 PTP CLOCK INFO
  
PTP Device Type: Grand Master clock - Boundary clock
  PTP Device Profile: Default Profile
  Clock Identity: 0xF4:4E:5:FF:FE:E5:95:0
  Clock Domain: 0
  Number of PTP ports: 20
  
Time Transfer: Linear Filter <<< Displayed when the clock is configured as a BC or a GMC-BC
  Priority1: 128
  Priority2: 128
  Clock Quality:
        Class: 13
        Accuracy: Within 1s
        Offset (log variance): N/A
  Offset From Master(ns): 0
  Mean Path Delay(ns): 0
  
Steps Removed: 0
  Local clock time: 23:16:53 UTC Jul 15 2015

Configuration example


switch# configure terminal
Device(config)# no ptp profile power
Device(config)# ptp mode gmc-bc delay-req
Device(config)# ptp transfer feedforward
Device(config)# end