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Rather than arguing about a horse that left he barn years ago, I believe the more interesting debate is to what degree a higher speed Ethernet should be able to leverage existing 10 GbE technology. My belief is that it should to the highest degree possible and for the longest period of time that it remains the most economical solution. To be specific, I believe that an Nx10G technology will be the best solution for some number of years. Not to say that an Nx20G, Nx40G or even Nx100G will not become practical and more economical in the future. At the point it provides compelling economically to implement we should revise the standard to support that. If you agree with this, then I further submit, again, that we should support all the existing 10G PHYs, including LAN-PHY and WAN-PHY versions. This will allow us to leverage the work that’s already gone into making these transportable across the WAN without making the problem for WAN vendors any worse than it is today. Given that essentially everyone is already providing solutions to the rate mismatch problem, it is unnecessary to fix what’s already been fixed.
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Stephen J (Steve) [mailto:sjtrowbridge@xxxxxxxxxx]
I fully agree with you. This should never have been a problem because bit transparency of the full physical layer is considerably more than what should be needed for transport of something called Ethernet. What should be important is transparency of the packet payload, characteristic information, traffic units, or whatever you want to call the stuff that is carried over an Ethernet network.
But what we learn from experience is that there isn't a lot of way to avoid that someone uses something in a way that was never intended.
We have discovered at least one router vendor who carries proprietary stuff (I assume OAM) in the preamble and insists that the preamble be carried transparently so as to not break this proprietary use. I understand that there exists a mapping of 10 Gigabit fibre channel into Ethernet that encodes something in the IPG.
I agree that this should never have happened, but we now see a lot of market pressure, resulting in some network operators and equipment vendors caving into the pressure to offer carriage of a 10G Ethernet signal in a fully bit transparent manner - every one of the 10.3125 Gbit/s being carried intact including the 64B/66B coding!
In reaction to a proposal that we now need to change the OTN bitrates in ITU-T to carry the full 10G BASE-R signal with 64B/66B coding over an ODU2-like structure with a higher bitrate, one of the participants quipped that it sounded like someone wants us to change the standard so that we can carry something that isn't Ethernet over something that isn't OTN.
What I am arguing for is that, for the next higher rate, we avoid defining different interfaces with slight difference in data carrying capacity. Doing this leaves open a crack that might be used improperly (or at least WHEN it is used improperly, it breaks something or introduces some unexpected constraint in the network).