Gigabit over 150 ohm STP
Just to emphasize my concern with your argument, I will use a
bit of rhetoric.
It would seem that the IEEE 802.3ab made a big mistake by focusing on a
4-pair, CAT-5 scheme rather than a 2-pair STP method of transmission. How
could the IEEE have made such big mistake? What will IBM and Taco Bell do if
they ever want to migrate to Gigabit?
As Geoff said, the DTE-PWR committee chose to use 4 pairs because
they have been proscribed by the EIA/ISO for years now and anyone
who is specifying their building infrastructure with an emphasis on
application flexibility has been using that approach.
We have not decided which pairs to apply power onto yet. This
is subject to study, presentation, and debate. I believe that it
is intuitively obvious to anyone that putting power on the "unused"
pairs will provide less risk to 10/100T applications than using the
data pairs. The subject of debate should and will be "How much less
risk?" If it is zero, then your points will gain relative weight. If there
is a measureable impact on 10/100T operation (our primary objective) then
your points will lose relative weight. I expect that we will see this risk
quantified by the next meeting.
HP ProCurve Networks
From: James M. Polk [mailto:jmpolk@xxxxxxxxx]
Sent: Wednesday, May 03, 2000 10:13 PM
To: Geoff Thompson
Subject: RE: Here's a new idea:
I'll take that challenge -- however, because I don't work for this company,
I cannot claim with a paycheck that it is accurate: IBM apparently has
300,000 users of STP that doesn't have 8 conductors. I understand that
Ethernet is either installed or planned throughout the company (again, only
But this is *all* of one very big customer.
Another large company that I believe is migrating from STP-TR to Ethernet is
Taco Bell. I don't know how many users they have -- but they aren't small --
and again, this represents *all* of a customer.
At the end of the day, do I think it's a large number of installations that
are affected by this? No. But I don't see why yet, we shouldn't attempt to
include everyone. Putting DTE Power on the 4 signaling pairs accomplishes
this. As without those 4 pairs -- you don't have any Ethernet.
If the Engineering exists and can be proven to work utilizing the signaling
pairs -- why isn't that the mode this committee pursuing?
This is what I'm scratching my head about.... at least ever since York.
At 12:40 PM 5/2/2000 -0700, Geoff Thompson wrote:
>For every soapbox there is yet another.
>Both 802.3 and EIA/TIA TR-41/42 Standards groups have been preaching for
>well over 5 years that all RJ-45 installations of "generic cabling" should
>be star wired and terminate all 4 pair in a single RJ-45.
>This was done for several reasons:
> 1) To make the cabling plant generic (i.e. application independent)
> 2) To provide a uniform platform for future applications
> 3) To provide a well characterized transmission environment
>Customers who did not do this were at risk of losing the capabilities of a
>generic cabling plant. In particular for number 2 the future applications
>are (at this time and from my point of view) 1000BASE-T and DTE Power.
>As for splitting 4 pair to 2 outlets, that works fine for 10BASE-T. It is a
>bad idea in terms of a 100BASE-T transmission system. The crosstalk from a
>10BASE-T into some of the older implementations of 100BASE-T can be
>As to your assertion that the 2 pair split-out represents "many" and STP
>Type 1 & 2 installations represent "Lots"...
>Sorry but we need better information than that. How about some quanitative
>input as to number of installations that are real-live candidates for
>DTE-Power applications and the percentage of the installed base that they
>At 03:29 PM 5/1/00 -0500, James M. Polk wrote:
>I believe there will be a greater impact on *not* engineering this on the
>Signaling pairs. Both 10 and 100 Ethernet utilize only two pairs, not 4
>pairs. So a minimum implementation of Ethernet is pairs 2&3, and nothing
>knows the wiser. Having power on those signaling pairs satisfies this
>minimum implementation. Any other implementation should ask the following
>How many customer sites have split off their 4 pair cabling for an
>additional station? Many
>How much STP Type 1 and Type 2 is there installed? Lots
>The cost of re-cabling these sites is significantly greater than the cost
>of the new equipment for VoIP and other such implementations that will
>utilize this NEW power capability.
>This will prevent the adoption of this committee's effort to whole customer
>sites at a time -- which I've never thought was a good philosophy, but
>seems to be what's going on here, IMO. This seems like a very exclusionary
>position, not inclusionary (which is how a standard should be).
>At 12:39 PM 5/1/2000 -0700, DOVE,DANIEL J (HP-Roseville,ex1) wrote:
> >Hi James,
> >It occurs to me that the detection method is irrelevant to
> >1000BASE-T operation as the link will not be up at the time
> >of operation. However, the issue at hand is whether you can
> >inject power at a mid-span in a way that is compatible with
> >1000BASE-T signalling requirements.
> >There have been some votes on this subject and my recollection
> >is certainly not the best thing to rely upon, but I recall
> >that 10/100T is a MUST while 1000BASE-T is a WANT.
> >Using pins 4,5 and 7,8 minimize the potential impact on 10/100T
> >but would likely have an impact on 1000BASE-T.
> >There are studies underway to understand just how much these
> >impacts are and whether they will exclude 1000BASE-T operation.
> >Dan Dove
> >___________ _________________________________________________________
> >_________ _/ ___________ Daniel Dove Principal Engineer __
> >_______ _/ ________ dan_dove@xxxxxx LAN PHY Technology __
> >_____ _/ ______ Hewlett-Packard Company __
> >____ _/_/_/ _/_/_/ _____ Workgroup Networks Division __
> >____ _/ _/ _/ _/ _____ 8000 Foothills Blvd. MS 5555 __
> >_____ _/ _/ _/_/_/ ______ Roseville, CA 95747-5555 __
> >______ _/ ________ Phone: 916 785 4187 __
> >_______ _/ _________ Fax : 916 785 1815 __
> >__________ _/ __________________________________________________________
> >-----Original Message-----
> >From: James M. Polk [ mailto:jmpolk@xxxxxxxxx <mailto:jmpolk@xxxxxxxxx> ]
> >Sent: Monday, May 01, 2000 10:11 AM
> >To: Bob Bell; tal@xxxxxxxxxxxxxx; stds-802-3-pwrviamdi@xxxxxxxx
> >Subject: Re: Here's a new idea:
> >It's Monday, so forgive this clarification, but are you asking Tal to
> >his scheme on the signaling pairs of a 10/100BASE connection as well as
> >4/5/7/8 on a 1000BASE-T connection? If not, I'd be curious if Tal could
> >this; if so.... then I'm being redundant again redundant again......
> >At 10:18 AM 5/1/2000 -0600, Bob Bell wrote:
> >>Tal -
> >>One of the objectives the group stated was to test for powerablity on
> >>same wires as the power would be provided. In addition, it is desirable
> >>that the powering and thus the testing be done in such a manner that the
> >>signal carrying capability of the wire pairs not be compromised (this it
> >>allow it to work with 1000BaseT. Could your scheme meet these two
> >>Bob Bell
> >>At 02:27 4/30/2000, Tal Weiss wrote:
> >>>Hi all,
> >>>Since this is my first contribution to the forum and I'm not sure that
> >>>email forwarding system works, I'll be brief.
> >>>I read the different discovery process approaches and I want to offer
> >>>something completely different!
> >>>All of the proposals in the forum are analog by nature, and lack in
> >>>I was able to construct a digital "power-identity-chip", costing less
> >>>1$, to be implemented inside the powered-IP-phone. This was done using
> >>>off-the-shelf parts.
> >>>The chip is powered remotely from the switch using 5 Volts (a simple 5K
> >>>pull-up resistor does the trick).
> >>>The power-enabled-switch polls the line for "power-identity-chip" (this
> >>>be done across wires 4,5 or 7,8) and when a phone is attached the chip
> >>>found (CRC protected communication, of course).
> >>>This chip then tells the switch what it's power requirements are!
> >>>which wires, power, MAC address and so on...)
> >>>The power-enabled-switch then applies the correct power using the
> >>>This approach has been tested in the lab and works using different
> >>>schemes from more than 200 meters!
> >>>No false alarms and no misses.
> >>>I know this is different than all the other approaches mentioned above,
> >>>it works so well I couldn't resist sharing.
> >>>If more information is needed I'll be glad to supply it!
> >>>Tal Weiss
> >>>Congruency Ltd.
> >>>23 Hasivim St.
> >>>POB 7813
> >>>Petah-Tikva 49170, Israel
> >>>Email: tal@xxxxxxxxxxxxxx
> >>>Phone: 972-3-9212322-218
> >>>Fax : 972-3-9210757
> >>Bob Bell
> >>Cisco Systems Inc.
> >"At the end of the day... the most committed win!"
> >James M. Polk
> >Sr. Product Manager, Multiservice Architecture and Standards
> >Enterprise Voice Business Unit
> >Cisco Systems
> >Dallas, Texas
> >w) 972.813.5208
> >f) 972.813.5280
> > www.cisco.com <http://www.cisco.com/>
>"At the end of the day... the most committed win!"
>James M. Polk
>Sr. Product Manager, Multiservice Architecture and Standards
>Enterprise Voice Business Unit
> www.cisco.com <http://www.cisco.com/>
"At the end of the day... the most committed win!"
James M. Polk
Sr. Product Manager, Multiservice Architecture and Standards
Enterprise Voice Business Unit