News Details

by Dale Humphries 

Avalon's Senior Systems Engineer Mike Anstey visited Geneva from May 31 to June 7, attending the third Study Group 15 (SG15) plenary meeting of the 2009-2012 study session. The ITU-T's Study Group 15 is dedicated to the development of "standards on optical transport networks and access network infrastructures, systems, equipment, optical fibres and cables, and their related installation, maintenance, test, instrumentation and measurement techniques, and control plane technologies to enable the evolution toward intelligent transport networks," including ITU-T recommendations G.709, G.798, and G.7041.

This Spring's session saw the members of Mike's SG15 group (Q11) agree to a number of changes to the standards under their purview: G.709 will be updated to include additional Infiniband interfaces; G.798 will include new information about OTUk-AIS alarm suppression, among a host of other changes proposed during interim meetings; G.7041 also underwent a number of modifications; a new draft of G.Sup43 came under review and was accepted, solidifying the details of mapping 10GE signals in over-clocked OTU. Q11 also discussed the future of OTN technology, holding preliminary talks about the next Highest OTN Rate - the as-yet undefined OTU5 - and agreeing to add a new G.709 Living List study point. This is sure to be a hot topic at future plenary meetings as OTU5 takes shape.

Among these changes, the key point of discussion for Mike and his colleagues was the development of a new recommendation, g.hao, for the Hitless Adjustment of ODUflex (HAO). Huawei proposed a functional model for the new recommendation, and, by the end of the session, an initial draft for g.hao had been submitted, although there will be much discussion to be had in interim sessions before the recommendation itself is finalized.

The Q11 group also collaborated with a couple of other subgroups within SG15, particularly Q6 and Q13. Q11 and Q6 wrestled with the question of whether certain transmission rates which had only been mentioned in G.sup43 should be standardized in G.709; the two groups ultimately decided against amending G.709 and concluded that Q6 should continue with the long-standing policy of only defining physical interface parameters for rates defined in the normative standard, i.e. G.709, as opposed to the supplements.

Meanwhile, Q11 and Q13 met jointly to discuss OTN timing transparency, in particular the details of which unit intervals of phase information were sufficient for STM-1 mapping and 1GE; Q11 also consulted with Q13 over the bandwidth (and other) requirements for carrying timing information over OTN, while noting that the models Q13 used to build their simulations might be insufficient in reproducing OTN timing transparency for systems with higher orders of muxing.

As always, this last round of standards meetings offered an informative glimpse into the future of optical networking technologies. Of particular interest were the tentative first steps towards delineating the framework of the next OTN rate, and Avalon's engineers look forward to taking part in the future discussions, debates, and collaborations which will determine the shape of this still-nascent technology.