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[EFM] Liaison from ITU-T Q4/15

Dear members of the Ethernet in the First Mile Task Force:


At their January 2004 Rapporteur Group meeting, ITU-T Q4/15 generated a liaison statement to 802.3ah.  It may be found at


As this liaison requests that changes be made to our draft, I felt it best to bring it to the attention of the group now so that we may come prepared to discuss it, rather than waiting until the opening EFM session to bring it to the attention of the group.


In essence, Q4/15 likes the Link Aggregation and Aggregation Discovery procedures that we have defined in our Clause 61 so much, they have decided to reference them in their project.  They also note the ATIS T1E1.4 has also referenced them in their M2DSL project.


Accordingly, Q4/15 has defined G.994.1 (G.handshake) codepoints to support these functions.  They have placed them at the top level (Level 1) of the G.994.1 codepoint tree, which makes them generic functions, available to all PHYs.  As a result, T1E1.4 is using these same codepoints for their standards.


In their liaison, Q4/15 observes that we, too, could use these Level 1 codepoints for our purposes (rather than using those that we currently have defined in our own codepoint trees), and requests that we do so.  In addition, they state that they have added a variable silence mode in G.9941.1, and they request that we use this mode, rather than defining one in our own codepoint trees, as we currently have done.  Note that we have no obligation to do so, as we have been assigned two Level 1 codepoints by Q4/15 for our own purposes.


As a practical matter, if we do was they suggest, it would entail deleting a substantial part of the tables in Annex 61, and it would change some of the references in Clause 61.  It’s fair to say that it would shorten the draft, with no reduction in functionality.


I will submit comments for these requested changes on behalf of Q4/15, so that they appear in the comment database.


--Barry O’Mahony

Copper STF Chair