Re: [802.3BA] Discussion on 40G for => 10 km SMF
On Fri, 8 Aug 2008, Jesse Simsarian wrote:
I believe that we should be focused on the problem at hand of finding
the best solution for 40GbE on SMF. I have heard the opinion that 40G
serial will give us higher capacity, which is not the case here where
one 40GbE is carried on a fiber. Of course there are WDM optical
transport systems that operate at 40 Gb/s today and will continue to do
so in the future. However, I do not think we should be making decisions
here based on the future development of colored optical transport.
Looking at the development of 1GE:
SX/LX, then ZX, then CWDM band ZX, then DWDM band ZX, first in GBIC, then
in SFP form (intermixed).
With 10GE, first there was Xenpak, then X2, then XFP, and now SFP+. We're
seeing DWDM colored Xenpaks and XFPs, don't know if they're starting to
become available in SFP+ form. Vendors choosing Xenpak och X2 because this
is the only form factor that can fit LX4 optics hurts us now as we want to
standardize on XFP (to get rid of the framer from the optical module as
this means we can use the same pluggable for POS/10GE LAN/WANPHY).
So, if the aim for 40GE as "let's get it to market quickly, and people
won't use it much after 2015" then by all means, CWDM solution is ok. If
the aim is to create a standard that can be used in both datacenter and
ISP market for a long time, 40GE serial is the way to go as this enables
later industry standards for 40GE SM with longer reaches as well as WDM
enablement with colored pluggable optics and external CWDM muxes.
Historically, in the 5+ year timeframe after the standard has been
adopted, serial solutions have prevailed and the WDM solutions have gone
away.
I have little insight in all the cost benefits etc of the proposals, I'm
just giving end user perspective from how I have experienced development
of ethernet pluggables the past 10 years.
If serial and CWDM solutions has even close to similar cost structure
initially, I think the serial solution is the way to go.
--
Mikael Abrahamsson email: swmike@xxxxxxxxx