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[802.3af] Your TR Comment

Please post your diagram to the reflector ASAP


There exists a scenario whereby two or more PDs with different power mixing schemes,
when PSE-Midspan powered, may cause damage to a legacy 802.3 data switch to which
the PDs are attached which may be sharing unused pair termination.

Chad to provide a drawing if necessary.


There are several ways to prevent this damage to legacy 802.3 equipment (listed in order
of least desireable):
1. Disallow the Midspan PSE
2. Force environment B for Midspans
3. Define an environment B- that can address this mixed scenario
4. Mandate a full diode bridge on each power pair in the PD
5. Mandate a half diode bridge on each power pair in the PD
Proposed Response
Comment Status X
Response Status O

Jones, Chad Cisco Systems

| Geoffrey O. Thompson                    |
| Vice Chair,  IEEE 802                   |
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