Re: [802.3af] Midspan PSEs using alteranative A
Hello Dirk,
The reason is that the mid-span PSE is a passive device (ostensibly) in terms of
signal transmission. It therefore must conform to the signal transmission
requirements of a single cat 5 connecting hardware device. The requirements
are(in a nutshell) 40 dB NEXT, 14 dB RL, and 0.4 dB insertion loss at 100 MHz.
The cat5e requirements are: 43 dB NEXT, 18 dB RL, 0.4 dB insertion loss, and 35
dB FEXT at 100 MHz.
Generally, cat5 supports 10 BaseT and 100 BaseTX and Cat5e supports 1000baseT,
... more or less ...
If you can build a device with two connectors, and two1:1 transformers (one for
each pair) that meet the above requirements, then there is probably no reason
that alternative A could not be supported. Of course, we are not allowed to talk
about cost.
Sterling Vaden
Superior Modular Products
33 Superior Way
Swannanoa, NC, USA 28778
Ph: 828 298-2260
"Mohl, Dirk Steffen" wrote:
> Hi,
>
> I have a question regarding midspan PSEs.
>
> In Draft 3.1 page 37 line 22 midpsan PESs are limited to alternative B.
>
> Is there a reason to forbid midspan PSEs using alternative A ?
>
> (The reason for this question is using midspan PSEs in a 2-pair- cable
> environment)
>
> Thanks for your Help
>
> Dirk
>
> ----------------------------------------------------------------------
> Dirk S. Mohl
> Automation and Network Solutions / AEB
>
> Hirschmann Electronics GmbH & Co. KG
> Stuttgarter Strasse 45-51
> 72654 Neckartenzlingen, Germany
>
> Phone +49 7127 14 1622
> Fax +49 7127 14 1600
> mailto:dmohl@nt.hirschmann.de
> http://www.hirschmann.de
> ----------------------------------------------------------------------