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All,
Upon further examination of the final state of this draft, I believe the MPD isolation requirements are sufficient. We should avoid any issues that might arise from Isolated MPSEs fed by incompatible power supplies. George also pointed out that the existing
isolation text does need an update, though:
Change:
An isolated MPSE that has more than one isolated MPSE MPI does not require electrical power isolation between isolated MPSE MPIs.
To:
An isolated MPoE System that has more than one isolated MPSE MPI does not require electrical power isolation between isolated MPSE MPIs.
This edit should resolve my comment on the Isolated MPoE system and I would be willing to retract my comment on the Grounded system section.
Jason Potterf
Principal Hardware Engineer, Cisco
From: George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx>
Sent: Friday, October 24, 2025 2:39 PM To: STDS-802-3-SPMD@xxxxxxxxxxxxxxxxx <STDS-802-3-SPMD@xxxxxxxxxxxxxxxxx> Subject: [802.3_SPMD] Closing remaining comments - R1-40 & R1-41 All – I encourage you to use the reflector to close the remaining comments. I will start a thread on each. This one is for R1-40 & R1-41, because they are related.
Both comments are about how MPI Group membership may or may not relate to isolation requirements.
Comment R1-40 is for isolated MPoE systems, and comment R1-41 is for Grounded MPoE systems.
Generally, belonging to an MPI group means that a physical device may incorporate more than one connection to the power bus. This creates some question over whether ports (in the same MPI group) may need to be isolated from each other. Discussion was over whether the MPI group itself matters – as an MPI group was a construct for LLDP management. For example, a device might have multiple MPIs that are members of the same MPI group, and might also have multiple MPIs that are associated with different data links and therefore different MPI groups.
The suggested remedies responses to Comments R1-40 & R1-41 noted that MPIs within an MPI group to be isolated (for isolated MPoE systems). Comment R1-40 was a proposed ACCEPT, and comment R1-41 (grounded MPoE systems) was proposed ACCEPT IN PRINCIPLE with a rewording.
However, the issue being discussed was whether we actually wanted to require isolation in both cases. Further discussion to build consensus is needed.
George Zimmerman, Ph.D. President & Principal CME Consulting, Inc. Experts in Advanced PHYsical Communications 310-920-3860
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