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Hi Snigdho! I've got some questions on your comments and I'll take a
stab at some answers... Regards Greg Bardalai, Snigdho wrote: There are three basic requirements in the signaling draft (a) characterization of WSON signals, (b) bi-directional distributed wavelength assignment for WSON signals, and (c) an option for specifying the distributed wavelength assignment method to be used at each node. Items (a) and (c) were from Young and my original draft and (b) was from Sugang, Hiroki and Dan King's draft which the chairs mentioned we should merge with ours. Is item (c) bothering you? Or the combination of (a) with (b) and (c). We wanted the WG's opinion on item (c). --> In the e-mail I sent concerning the WSON Framework document I brought up the issue of "lightpath" definition. In a more detailed reading of G.709 and G.872 I got the impression that OCh is a bit too restrictive. In G.709 it is defined from 3R to 3R. Now we want to include wavelength converters even if we are not currently dealing with impairments and most wavelength converters are regenerators (2R or 3R) with tunable lasers. G.872 doesn't consider the wavelength of the optical signal part of its characteristic information hence an OCh can go through a wavelength converter and they give an example in Appendix I. Agree. Note that RFC4328 covers the standard G.709 digital hierarchy. For signals not in the G.709 digital hierarchy the concepts and terminology of G.709/G.872 still apply (with some caveats): the OCh (optical channel), OMS (optical multiplex section), OTS (optical transmission section), and Physical Media Layer (the optical fiber itself). It seems that G.709 and G.872 have slightly different notions of what an OCh is (G.709 seeming more restrictive). Now from the practical side of things there are standards at the ITU-T that actually talk about characterizing the signals like G.696.1. To determine receiver compatibility we can run into trouble with a higher layer signal designation such as STM-256 since different modulation (RZ, NRZ) maybe used. Hence the ITU-T started defining signal classes by (a) modulation, (b) modulation parameters (if any), (c) bit rate, and (d) FEC. --> Do you mean "analog bandwidth"? Although G.872 are aimed at transport of digital signals, I recall a request from someone to include some minimum ability to deal with "analog signals" for an application where wireless signals were put over the fiber without much processing. If you meant "bit rate" for a digital signal compatibility with the receiver and any OEO based wavelength converters...
-- =================================================== Dr Greg Bernstein, Grotto Networking (510) 573-2237 |