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I think we need to be careful what we mean by “It just reduces the expected percentage of channels that would be upgrade candidates”. The question has to be asked what you are upgrading from. Pete’s analysis seems to me to be saying that if we choose a 19dB budget then we could upgrade 100% of the 40km 10GBASE-ER channels which is obviously very important from an Ethernet standpoint. Mike Dudek QLogic Corporation Senior Manager Signal Integrity 26650 Aliso Viejo Parkway Aliso Viejo CA 92656 949 389 6269 - office. Mike.Dudek@xxxxxxxxxx From: Kolesar, Paul [mailto:PKOLESAR@xxxxxxxxxxxxx] Right you are Pete. It just reduces the expected percentage of channels that would be upgrade candidates. That aspect is really what is in trade against various power budgets. As with the multimode reach discussions, this question really should be addressed with respect to the cost of the alternatives. Lower channel coverage capability means either: 1) the channel must be upgraded or replaced, or 2) the user must deploy transceivers that are more capable than 40GBASE-ER4. We should see some cost analysis of these scenarios to guide our decision. Paul From: Anslow, Peter [mailto:panslow@xxxxxxxxx] Paul, Yes, I took the multimode number by mistake from: The maximum link distances for multimode fiber are calculated based on an allocation of 1.5 dB total connection and splice loss. Thanks for checking that. It does not, however affect the conclusion. The corrected response is therefore: The maximum channel insertion loss for 10GBASE-ER from Table 52-24 is 11 dB with 2 dB for connectors at 1550 nm. This is (11-2)/40 = 0.225 dB/km This covers about 35% of installed links on Figure 10-8 of G.Sup39. 0.225 dB/km at 1550 nm is equivalent to 16.75 dB for a 40km link at 1264.5 nm. If we add 2 dB for connectors 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 From: Kolesar, Paul [mailto:PKOLESAR@xxxxxxxxxxxxx] Pete, Thanks for the loss analysis. Clause 52 says the connection loss allocation for 10GBASE-ER is 2 dB. The maximum link distances for single-mode fiber are calculated based on an allocation of 2 dB total connection and splice loss at 1310 nm for 10GBASE-L, and 2 dB for 30 km total connection and splice loss at 1550 nm for 10GBASE-E. Using 1.5 dB would not necessarily ensure an upgradable channel. Paul From: Anslow, Peter [mailto:panslow@xxxxxxxxx] 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 |