1. Maintenance Items
  2. 0394
  3. Request
Requested revision
Standard:IEEE 802.1AS-2025Clause:10.7.2.5
Clause title:Interval for sending the gPTP-capable TLV Signaling message
Rationale for revision
Opposed to Announce (10.7.2.2) and Sync (10.7.2.3) message intervals, the interval definition for gPtpCapable signaling messages does not specify a tolerance. The interval of gPtpCapable signaling messages is the least important interval in the operation of IEEE 802.1AS. In the view of the requester, gPtpCapable message intervals should not be specified stricter than Announce messages intervals.

This present revision request was triggered by a finding reviewing the AVNU test specification for IEEE 802.1AS. Because of the missing tolerances, the test specification requires the gPtpCapable interval to be within 0.04 percent of the nominal interval, which makes no sense for real implementations.
Proposed text
Remove Note 3 in clause 10.7.2.5, it seems strange that clause 10 references clause 11.

Specify the same interval tolerances as those defined for Announce (clause 10.7.2.2) by adding the following clause at the end of 10.7.2.5 on top of page 167 (before NOTE 1):

Signaling messages containing the gPTP-capable TLV shall be transmitted such that the value of the arithmetic mean of the intervals, in seconds, between message transmissions is within ±30% of 2 (to the power of) currentLogGptpCapableMessaggeInterval. In addition, a PTP Port
shall transmit Signaling messages containing the gPTP-capable TLV such that at least 90% of the inter-message intervals, in seconds, are within ±30% of the value of 2 (to the power of) currentLogGptpCapableMessaggeInterval. The interval between successive Signaling messages containing the gPTP-capable TLV should not exceed twice the value of 2 (to the power of) currentLogGptpCapableMessaggeInterval in order to prevent causing an gPtpCapableReceiptTimeout event. The GptpCapableTransmit state machine (see 10.4.2) is consistent with these requirements, i.e., the requirements here and the requirements of the GptpCapableTransmit state machine can be met simultaneously.
Impact on existing networks
None
Originator
Name:Martin OstertagEmail:mailto:martin.ostertag@zhaw.ch
Affiliation:ZHAW Zurich University of Applied Sciences
Submitted:2026-03-31