It seems intuitive, but according to basic queuing theory splitting up a single channel into N fixed smaller channels makes the response time (T), N times worse, where T= (queuing + transmission time). -----Original Message----- From: Rod Beck [mailto:Rod.Beck@hiberniaatlantic.com] Sent: Monday, August 17, 2009 9:14 AM To: Richard A Steenbergen Cc: nanog@nanog.org Subject: RE: TransAtlantic 40 Gig Waves Rod, do you know if the 40G waves increased the spectrum efficiency of your fiber? On land systems they pretty much break even, i.e. you can have a 100GHz 40G channels or 4x25GHz 10G channels but at the end of the day you still get the same amount of signal out of the fiber. I don't know whats being done on undersea cables though. Eventually this will get better too, and 40G will become the "native" wavelength standard with 10G being muxed onto them, similar to what we saw with the transition from 2.5G->10G 10 years ago. -- Richard A Steenbergen <ras@e-gerbil.net> http://www.e-gerbil.net/ras GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC) "Rod. This is direct from engineering: The number of wavelengths or channels Hibernia have on their DWDM infrastructure remains the same, however now each wave can be at a rate of 40Gb/s instead of only 10Gb/s. In the extreme case, we get 4 times the capacity, but in reality, because of the existing installed 10G's, we would not necessarily swap out all existing cards. We could say the overall increase in capacity is "up-to" 4 times. The enabling technology is based on advanced encoding techniques allowing a greater rate of symbol transfer."