TransAtlantic 40 Gig Waves

Holmes,David A dholmes at
Mon Aug 17 17:23:22 CDT 2009

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 at] 
Sent: Monday, August 17, 2009 9:14 AM
To: Richard A Steenbergen
Cc: nanog at
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 at>
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1


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." 

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