Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

Re: Signal vs. Idle debate (was: Here's a new idea)

Among your omissions is the fact that you can't power a 1000BASE-T
interface without inflicting power on the signal pairs.  I'm not bringing
this up because I think that powering 1000BASE-T is the most important
objective for the committee, rather I'm pointing out that it seems like
solving the power-over-signal problem really is the most inclusive objective.


At 10:54 AM 5/4/00 -0400, Mike_S_McCormack@xxxxxxxxxxx wrote:
>There are conflicting opinions on where the priorities should be.  I'll be
>to take up the challenge to distract you from your work and make you all wade
>through my opinions for a while.
>There are a number of customer who have previously purchased Ethernet
>hubs/switches/routers and deployed them in their facilities.  I believe that
>approximately 100% of the installed base fall into this category of investors.
>(I suspect that the number of us who are using near death alpha prototype
>equipment at home is less than a percent - perhaps I'm wrong.)
>Some number of the above sub-group of Ethernet users have "cheaped out" and
>either run just two pairs or have decided to alter their plant and run two
>Ethernet links over the installed four pair.  I would conjecture that the vast
>majority of the people/organizations that did either of these thing knew they
>were cutting corners.  Some potential users may very well have installed other
>facilities that they are migrating to Ethernet.  These
organizations/people may
>have installed the facilities in good faith and may now find that they can not
>take full advantage of the breath of the Ethernet, they are already precluded
>from 1000BASE-T.
>Of the power schemes that have been proposed, only the idle pair proposals
>addressed preserving the investment of all of the current 802.3 users by
>allowing mid-span power insertion.  While the signal pair camp may claim they
>are preserving the wiring infrastructure of a proportion of the of the 802.3
>users ignored by the idle pair camp, they require every customers - including
>those that followed the recommended practices in good faith - to dispose
of all
>of their existing hubs/switches/routers to make room for the users (or 
>users) who have cheated or sub-standard plants.  This is a huge expense to 
>on the backs of customers who have properly engineered plants just to allow a
>minority the special advantage of not having to come up to spec.
>I am of the opinion (and trust me this whole mail is just opinions) that the
>real markets for power over Ethernet are not yet discovered, and between now 
>then a huge number of Ethernet ports will ship.  If we require customers to
>replace all their wiring closet equipment, the adoption rate of power will 
>be in
>fractions of a percent of the total shipments forever.  If we provide a means
>for users do not have to fork lift all their capital equipment, we will allow
>the power applications to be added incrementally and the market will develop.
>The 802.3 has effectively already told the two pair users they are at the 
>end of
>the road.  We did this with the 1000BASE-T standard.  These users should
not be
>expecting the 802.3 to provide them any new technology on their old plants, we
>have demonstrated this to them previously.  Why would we turn around and now 
>we were just kidding about not supporting two pairs, should we also re-examine
>if we can run 1G on two pairs?
>I am willing to characterize the performance of powered systems over CAT3 / 
>per 568.  Are we really saying we want to characterize this as well as every
>form of STP/UTP that could "commandeered" for Ethernet as well as every
form of
>24/26 gauge telephone wire (with and without stubs and / or but slices) 
>....?  I
>for one would like a chance at completing a spec.
>I would say the idle pair mentality is the most inclusive, it allows use of 
>of the existing users to upgrade and the signal pairs group is the most
>exclusive, allowing no users to upgrade (without a forklift.)  Limiting the
>scope of study to properly engineered plants allow at least some users to
>the benefits of powered Ethernet while open ended standards will never 
>The distraction of my opinion storm is over, you may return to your real work.