To: ITU-T Q12/15, Q14/15, and Q11/15
Thank you for your liaison SG15-LS121: “LS on OCL, Information modelling of MCC and media”. The ONF OIMT & OTCC Projects have progressed on many aspects of the Core Information Model.
With regard to media, the use case of an express channel in a ROADM has led us to consider an additional type of media channel, other than a network media channel. In general, this is a media channel whose frequency slot overlaps with the frequency slots of one or more network media channels, but does not necessarily share their ports. G.872 describes media channel concatenation, but does not describe media channels that start and end on two ports of any serial concatenation of media channels. The ROADM “express channel” is an example of this type of media channel which when switched, can effectively switch all network media channels that share its frequency slot. A construct has been discussed in the model for this, and we request that it be considered in G.media and G.media-mgmt.
In G.798 and G.872, the adaptation “OTSi/<digital OTN client>” is found in various figures. Considering that an OTSi is defined as an optical signal (G.959.1) and that it only emerges from the optical signal modulator/demodulator, it is suggested that the electrical/optical separation be more clearly shown by identifying the electrical signal into the optical signal modulator/demodulator. This would reserve the “OTSi” label to be used only as the output of the optical signal modulator/demodulator. Digital OTN clients would then adapt to an electrical CI layer as shown in the following diagram:
Terminology we found confusing are SOTU and MOTU. As described in G.798, they appear below the optical signal modulator/demodulator. As this is an optical signal, it is unclear why they are named using a client name (the “OTU” string). It would seem that this should be above the optical signal modulator/demodulator. There may be a corresponding OTSiG for an MOTU. The clarity sought is again related to the separation between electrical and optical, and also to minimize use of client naming for server constructs.