Requested revision
Standard: | 802.1AS | Clause: | 11.4.2.4 |
Clause title: | correctionField (Integer64) |
Rationale for revision
Table 11-5 indicates that for messageType Pdelay_Req, the value of the correctionField contains corrections for fractional ns. This is not correct in 802.1AS. In general in IEEE 1588, the only way that fractional ns corrections can be included in the correctionField of Pdelay_Req is if there are end-to-end transparent clocks present that timestamp with fractional ns precision. However, 802.1AS does not allow (and does not describe) end-to-end transparent clocks, and therefore fractional ns cannot be present in the Pdelay_Req correctionField.
Note that this change was proposed in a comment during the sponsor ballot recirculation for P802.1AS-Cor-1 (comment #6 in the final comment resolution for draft D3.1). The comment was rejected because it was out of scope, but the committee thought it would be desirable to make this fix in P802.1ASbt, and indicated the editor should submit this item for entry in the maintenance database.
Proposed text
Remove Pdelay_Req from the messageType column of row 2 (not including the table header) of Table 11-5.
Impact on existing networks
This has no impact on existing networks; it simply adds clarity to 802.1AS.
Originator
Name: | Geoffrey M. Garner | Email: | gmgarner@alum.mit.edu |
Affiliation: | Broadcom, Hirschmann, Marvell, Siemens | ||
Submitted: | 2013-06-24 |