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Hi, As noted in the draft minutes of yesterday’s SMF Ad Hoc meeting, there were a couple of questions related to the maximum channel loss: · What coverage of links is the 18 dB loss for 100GBASE-ER4 equivalent to? · What loss does the channel loss for 10GBASE-ER translate to for 40GBASE-ER4 wavelengths? The answer to the first question is that (18-2)/40 = 0.4 dB/km at 1294.53 nm (lowest wavelength for 100GBASE-ER4) is equivalent to about 50% of installed links on Figure 10-8 of G.Sup39. The maximum channel insertion loss for 10GBASE-ER from Table 52-24 is 11 dB with 1.5 dB for connectors at 1550 nm. This is (11-1.5)/40 = 0.2375 dB/km This covers about 50% of installed links on Figure 10-8 of G.Sup39. 0.2375 dB/km at 1550 nm is equivalent to 17.25 dB for a 40km link at 1264.5 nm. If we add 1.5 dB for connectors (assuming that we are going to upgrade an existing 10GBASE-ER link) we get 18.75 dB which fits well with the proposed 19 dB maximum channel insertion loss for 40GBASE-ER4. Regards, Pete Anslow | Senior Standards Advisor |