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[802.3af] FW: ETSI standard for Line power for IP terminals

To all -

I received this pointer and thought it would be good to forward it on to

Cheers ---- Bob

-----Original Message-----
From: Colin Wilson [mailto:cpwilson@xxxxxxxxx]
Sent: Tuesday, 24 July, 2001 10:23 AM
To: standards-announce@xxxxxxxxx
Cc: shamilto@xxxxxxxxx; mphipps@xxxxxxxxx; rtbell@xxxxxxxxx;
Subject: Fwd: ETSI standard for Line power for IP terminals

ETSI work group TC-AT is developing a standard for line powering of ip
phones using ethernet and this also implies a requirement for the equipment
supplying power to the phones.  There is a little addition beyond 802.3af
in that it incorporates reduced line powering in the event of a network
failure, similar to basic rate restricted power.  The intent is to get this
standard ratified at the September meeting but there is still quite a bit
of work to be done so we can input to the standard if we wish.

An ETSI study into the standards for IP phones was published as TR 101 941
and available at:

Following the completion of the study the draft standard for line powering
was started as ES 201 910, which is available at:

The work was originally pushed by Phillips but is now being driven by
Telecom SA.  Anyone working in this area please contact me to set up some
discussions in a smaller group.


Colin Wilson

>X-Mailer: Novell GroupWise 5.5.4
>Date: Wed, 18 Jul 2001 14:49:18 +0200
>From: "Robert Jürgens" <JURGENRW@xxxxxxxxxxxx>
>To: <cpwilson@xxxxxxxxx>
>Subject: Line power for IP terminals (resend)
>Dear  Colin
>Attached please find a draft specification: "Line power for IP terminals"
>ES 201 910 V1.1.1 (work item DES/AT0020013 ) for your comment and
>input(Iptermlinepowerd2.doc). I have taken the proposal that was discussed
>and accepted at the March meeting and compiled it in the correct ETSI
>format, adding what I could.
>I will appreciate it if you can have good solid look at the specification
>and provide some comments. As you will see, there is still a number of
>items outstanding and your input will be highly valued. Please take note
>of the 'issues" paragraph at the end of the specification.
>If possible, I would like to have the document approved at the September
>meeting. (Since the scope of this document is outside of my level of
>expertise, I therefore will have to rely on your expertise.)
>About the Specification:
>The specification is based on the IEEE 802.3af draft 1.1, DTE Power via
>the MDI  (also attached) as decided in ETSI. As you will see, IEEE
>specifies the power supply characteristics on the LAN side (PSE) as well
>as the characteristics for the terminals (PD's) to be able to receive
>power from the LAN. This was accepted "as is" in the last ETSI meeting.
>Additional to the above, the ETSI specification addresses a possible power
>fail situation on the LAN side, which will leave the IP terminal without
>power resulting in basic communication breakdown. (The scope of the IEEE
>specification does not cover the reliability or interruptability of the
>power supply to the terminal.) To achieve basic emergency communication
>with a line powered IP terminal in the event of a power fail, the current
>proposal is to specify i) limited (emergency) back up power for the LAN
>ii) reduced power consumption for a limited number of "emergency" IP
>terminals (to conserve the limited LAN power) and iii) a means of
>communicating the switch over from normal to limited power (and visa
>versa) to the terminals when the power failure (restoration) occurs.
>Main outstanding areas are:
>Definition of messages to convey the different power states of the Line
>Specification of the backup power when the normal LAN power supply fails.
>Please do not hessitate to call me or mail or fax.
>Kind regards and thank in advance.
>Robert Jürgens
>Rapporteur ETS WI DES/AT-020013
>TC AT Digital workgroup
>Telkom SA - Technical Product Management
>tel +27123111041
>fax +27123285312
>mobile +27825541270
>emial: jurgenrw@xxxxxxxxxxxx
>This message was also sent to Ed Hay of Mitel