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

Re: A proposal for the "Five Criteria"

FWIW: The issues in the first criteria about cost effects. Centralized 
powering should lower the overall systems cost by eliminating the multiple 
local power supplies (wall warts) and changing the requirements for UPS 
support for telephony devices and other saftey type devices. I think that 
this issue can be very successfully addressed.

At least IMHO ---- Bob Bell

I like this proposed text in general.

At 12:02 PM  9/23/99 , Mike_S_McCormack@xxxxxxxxxxx wrote:

>In order to perform productive work at the Power Over MDI
>Study group meeting next week in York, I?m going to float
>the following proposed text.  I think that if we have a good
>starting point, then we can address the "Five Criteria" (see
> ) next week
>we stand a chance at getting a PAR.
>1) Address the "Broad Market" criteria:
>- Board set of applications:
>- Multiple vendors, multiple users.
>- Balance cost, LAN vs. attached stations.
>Currently three groups that have presented information,
>    telephone stations (estimated 8M nodes in 2001,)
>    wireless access points (estimated 700K nodes 2001,) and
>    theatre/lighting control (no numbers presented.)
>Additional applications have been identified such as
>surveillance cameras, card keys and office controls.
>34 companies/organizations sent attendees to the call for
>    interest meeting in Montreal.
>All attendees (44 people/34 organizations) to the call for
>    interest voted in favor of forming a study group
>20 companies/organizations indicated that they would work on
>    developing such a standard
>All devices presented currently require a power source, which
>is burdens the attached station.  The proposal to provide
>power over the MDI interface does shift that cost to the LAN;
>however, the centralization of power should reduce the
>over-all system cost to the end users.
>** Strictly speaking this presents the hardest criteria to
>     justify. **
>2) Address the "Compatibility" criteria:
>- Conformance with CSMA/ CD MAC, PLS.
>- Conformance with 802.2.
>- Conformance with 802 Functional Requirements.
>The proposed standard will be compatible with the CSMA/CD
>MAC and PLS, with currently authorized extensions.  Changes
>to the PLS will be required as the proposed standard
>development is a PLS change; however, compatibility with
>existing installations will be maintained.
>The proposed standard will conform with the 802.2 LLC
>interface, it does not effect it.
>The proposed standard will conform with the 802 Functional
>3) Address the "Distinct Identity" criteria:
>- Substantially different from other 802.3 specifications/
>    solutions.
>- Unique solution for problem (not two alternatives/ problem).
>- Easy for document reader to select relevant spec.
>The proposed standard will be an optional component to any
>of the twisted pair interfaces.  It differs from the
>existing 802.3 physical layer definitions as nothing in
>the 802.3 specification address powering devices, locally
>or through the MDI interface.
>Only a single powering system will be proposed.  Implementers
>will only have the option of producing equipment that either
>include or does not include this clause.  Optional inclusion
>is similar to 802.3ad, no implementor is required to
>implement link aggregation; however, if an implementor
>chooses to provide the functionality only one method is
>The proposed standard will be the only 802.3 component that
>will address power.  The standard will be formatted as new
>clause.  Together, these should make it easy for a reader to
>find relevant information.
>4) Address the "Technical Feasibility" criteria:
>- Demonstrated feasibility; reports - - working models.
>- Proven technology, reasonable testing.
>- Confidence in reliability.
>Presently, several proprietary implementation of the
>technology exist in the market place.  802.9 had developed
>significant information regarding power over MDI
>configurations during a study for their standard.
>Both the telephone network and 802.5 have always provided
>power over the same cable plant as the data signals.
>5) Address the "Economic Feasibility" criteria:
>- Cost factors known, reliable data.
>- Reasonable cost for performance expected.
>- Total Installation costs considered.
>The standard proposes to move cost from the end station to
>the LAN infrastructure.  Inclusion of power sourcing
>capabilities will not be a zero cost addition to hubs or
>switches, it is expected that both power sourcing and
>non-power sourcing units will be available in the
>marketplace.  Costs for customers who are not interested in
>providing power over their cable plant will not be
>adversely effected.
>The target areas are low power devices where the cost of the
>front end of the power supply is generally attributed to the
>number of components, not the current draw.  A centralized
>power system should be more economical than a distributed one.
>Should users be interested in backup power, centralization of
>the power source will drastically reduce power over separate
>backup power systems per station.
>Installation costs for two wiring systems, one for power one
>for data are at least twice the cost of a single wiring plant.
>While some installations would already have installed power
>systems, their would be no additional cost added to the
>installation of twisted pair cable.

Bob Bell
Cisco Systems Inc.