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Re: [802.3_ISAAC] Response for comments 77 and 78

Just to give some more background/understanding on the method for the delay constraint specification here is a previous presentation on a similar topic:

https://www.ieee802.org/3/dm/public/0725/Hutchison_Arunarthi_3dm_01_07272025.pdf

 

In gPTP it’s necessary to measure the PHY delay in each direction live before using each value, while for PAUSE operation specifying the combined Tx and Rx delay is sufficient, so completely different but makes use of some similar concepts.

 

Thanks
Scott

 

From: Scott Muma <00003414ca8b162c-dmarc-request@xxxxxxxxxxxxxxxxx>
Sent: Tuesday, September 15, 2026 11:29 AM
To: STDS-802-3-ISAAC@xxxxxxxxxxxxxxxxx
Subject: [802.3_ISAAC] Response for comments 77 and 78

 

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Hi Natalie and all,

Comments 77 and 78 were made for the specification of delay constraints which is also relevant to Clause 192.

 

In addition to any other response I would propose changing 192.12 as follows:

Replace text and table on page 292 with:

The combined transmit and receive data delay for an implementation of the PHY in a given mode shall not exceed the limits shown in Table 192–27. Transmit data delay is estimated from the input of a specified unit of data at the XGMII to the presentation of the same unit of data by the PHY to the MDI. Receive data delay is estimated from the input of a specified unit of data at the MDI to the presentation of the same unit of data by the PHY to the XGMII. Following the recommendations of 90A.7 for repeating delay variation patterns, the maximum intrinsic delay value is allocated to the transmit PHY and the minimum intrinsic delay value is allocated to the received PHY. For this purpose, the specified unit of data is the byte of data on the XGMII interface that corresponds to the first byte of data at the start of a TDD burst payload.

 

NOTE—The physical medium interconnecting two PHYs introduces additional delay in a link.

 

Table 192–27—Combined PHY Delay constraints

 

Operating mode              Maximum delay (ns)

PHY_S                                5 120

PHY_D                               11 776

 

Thanks

Scott

 

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