configure network-clock gptp ports peer-delay

configure network-clock gptp ports [port_list {only} | all] peer-delay [{allowed-lost-responses lost_responses_value} {initial-req-interval log_2_interval} {[asymmetr asymmetry_time [nanoseconds | microseconds | milliseconds | seconds] | neighbor-thresh [auto | neighbor_thresh_time [nanoseconds | microseconds | milliseconds | seconds]]}]


Configures gPTP peer delay parameters on the specified ports.

Syntax Description

port_list Specifies one or more of the switch‘s physical ports.
only Apply change only to specified port, even if port is master of a load sharing group.
all Specifies all of the switch‘s physical ports.
lost_responses_value The number of consecutive Peer Delay RequestPdelay_Req messages that the switch must send on a port without receiving a valid response before it considers the port not to be exchanging Peer Delay messages with its neighbor.
log_2_interval The interval between Peer Delay RequestPdelay_Req messages sent by the switch on the port when the port is initialized or when the switch receives on the port a message interval request TLV with linkDelayInterval value of 126. This value is in log2 seconds. The valid range of values is -3 (2-3 = 0.125 seconds) to 17 (217 = 131072 seconds).
asymmetry_time The time that the propagation delay from this switch to the neighbor is less than the estimated one-way propagation delay between the switch and its neighbor (which is also the time that the propagation delay from the neighbor to this switch is greater than the estimate). This value is negative if the propagation delay to the neighbor is greater than the estimate. It can be in nanoseconds, microseconds, milliseconds, or seconds. The maximum value is 4,294,967,295 nanoseconds (approximately 4.3 seconds). Let tIR be the propagation delay from this switch (initiator) to the neighbor (responder), tRI be the propagation delay from the neighbor to this switch, and meanPathDelay be the estimated one-way propagation delay. Then:
  • meanPathDelay = (tIR + tRI) / 2
  • tIR = meanPathDelay – asymmetry_time
  • tRI = meanPathDelay + asymmetry_time
neighbor_thresh_time The maximum measured mean of the propagation delay between this switch and the neighbor above which the switch considers the port unable to run gPTP. This value can be in nanoseconds, microseconds, milliseconds, or seconds.
auto Use a media specific default value for the neighbor_thresh_time:
  • Copper: 800 nanoseconds. This category includes short range copper cables such as SFP+ Direct Attach and QSRP+ Passive Copper.
  • Multi-mode fiber: 11 microseconds. This category includes the QSFP+ Active Optical cables. 11 microseconds allows 10 microseconds for 100BASE-FX 2 km plus 10% tolerance.)
  • Single-mode fiber: 550 microseconds. This allows 500 microseconds for our “LX100” transceiver plus 10% tolerance.
Note: These values may change. A draft of the 802.1AS corrigendum (P802.1AS-Cor-1/D1.1) specifies 800 ns for 100BASE-TX and 1000BASE-T.


  • Lost_responses_value = 3 (802.1AS 11.5.3)
  • Log_2_interval = 0 (1 second; not specified in 802.1AS)
  • Asymmetry_time = 0 (802.1AS
  • Neighbor_thresh_time = Copper media: 800 nanoseconds, fiber media: 4,294,967,295 nanoseconds

Usage Guidelines

Peer Delay messages determine whether a neighboring system is gPTP capable and measure the propagation delay on the link between the switch and a neighboring gPTP capable system.

  • allowed-lost-responses corresponds to 802.1AS parameter allowedLostResponses.
  • initial-req-interval corresponds to 802.1AS parameter initialLogPdelayReqInterval.
  • asymmetry corresponds to 802.1AS parameter delayAsymmetry.
  • neighbor-thresh corresponds to 802.1AS parameter neighborPropDelayThresh.


configure network-clock gptp ports 1-3 peer-delay allowed-lost-responses 5
configure network-clock gptp ports 1-2 peer-delay initial-log-interval -3
configure network-clock gptp ports 1-2 peer-delay neighbor-thresh 3 nanoseconds 


This command was first available in ExtremeXOS 15.3.

Platform Availability

This command is available on Summit X450-G2, X460-G2, and X670-G2 switches if the AVB feature pack license is installed on the switch.