RE: Signal vs. Idle debate (was: Here's a new idea)
Dan (and all)
Comments inserted
At 03:39 PM 5/4/2000 -0600, DOVE,DANIEL J (HP-Roseville,ex1)
wrote:
>
>Hi Norman,
>
>I have a few issues with the direction you are taking
the
>discussion so far. Let me explain.
>
>> If the market is growing very rapidly, then existing
owners
>> of (what will soon
>> be) absurdly bulky and expensive switches will be
small
>> fraction of the total
>> Ethernet market, and catering to those old switches
with
>> add-on boxes to
>> supply power will be a niche market.
>
>On the other hand, we are in the business of selling
products
>today to solve problems, not create them. There are plenty
of
>switches being sold today that support VoIP but don't
supply
>power because there is no standard for it. Are these
boxes
>"old, absurdly bulky or expensive"? I don't think so.
Some of
>them are highly integrated and very cost effective. I could
>give you examples but I think you know I am right.
Dan -- let's get a little realistic, here. We're not merely talking
about software to be downloaded to existing equipment to take advantage
of this new capability. DTE power means that customer has embraced a new
technology. That means new equipment to buy (in this case). Period. That
is a fact. Devices that expect power on either pair are just being built
-- therefore just bought -- therefore nothing is old or existing
regarding this coming Standard. If the switch manufacturers cannot build
a new switch module with power on that module -- shame on them. Companies
are already doing it and those that don't won't sell too much product.
Period. This is a fact.
As a point of reference towards past work the IEEE did: 802.1p/q
made everyone purchase new Ethernet switches because no one had built
their existing Switches with the ASIC capable of those additional bytes
to the Ethernet Header. This too is a fact. Period.
So your argument that the IEEE should (basically) only ever adopt
what doesn't impact the existing installed base is a fairly foolish
justification, IMO. And as far as cost of implementation is concerned --
this one cost customers a lot. Now -- I'm personally glad the IEEE did do
this work, there are great benefits to it.
Back to this topic, what will be engineered is power into existing
Ethernet Switching Chassis with new modules purchased by that new
technology customer.
I haven't done the numbers -- but for those that have a small fixed
Ethernet Switch in a closet (<50 ports) -- I'd be surprised if
building a cost effective external 'mid-span' power insertion device for
those installations were the norm, not the exception. Companies will
build new 'stackable' or 'fixed' or 'non-modular' chassis that will
supply DTE power. If you don't believe that's true -- wait and see. I'll
bet there will be many many offerings by many vendors by the time this
'Standard' is ratified.
>
>> Whether we choose the data pair or the
>> spare pair should be conditioned more on 1) the total
cost
>> to the buyer of
>> equipment designed with DTE power in mind, and
>
>As a standards committee member, I would put "must support
the
>installed base of equipment without interference" as a
higher
>priority than cost. The cost of ripping out existing gear
is
>substantial. But what I have to say is less relevant than
the
>decision by the committee to require compatibility with
10/100T.
Again, explain 802.1p/q mentioned above
>
>> 2) on the
>> needs of 1G and
>> faster links, than on the cost of existing
installations.
>
>Again, the committee has clearly expressed that 10/100T is a
>higher priority than 1000T. Unlike 10/100T, the Gigabit
stuff
>today actually operates very robustly. Much of the 10/100T
>installed base has been built with less-than-ideal
performance
>but customers want to use it. If you have a PC with an older
100T
>NIC installed, do you want its performance to be impacted by
the
>addition of mid-span patch panels that are designed to inject
>power on PDTEs?
I guess I don't understand why a PC would be connected to a Mid-Span
powering device and expecting power --- wouldn't that blow-up that older
NIC? I sure think that NIC couldn't handle -48Vdc on either pair.... but
I could be wrong.
In the case of the "spare pairs" no impact would
>exist. Sure, future 1000T products would have to deal with
power
>injection on their outside pairs, but 1000T is better equipped
>to do so with echo cancellers, FEC, and DSP
capabilities.
>
>> (Note that this
>> argument says that the woes of existing 4-wire
installations
>> is relatively
>> unimportant.) In other words, I think that
powering 1G is
>> more important
>> in the long term than cheaply adding on to 10M ports'
capabilities.
>
>Unfortunately, that is not the direction that the committee has
>already committed to. Support for 1000T should not be demanded
at
>the expense of either reliable or inexpensive 10/100T
operation.
>
>> -- Norm
>
>Best Regards,
>
>Dan Dove
>HP ProCurve Networks
>
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