nanog mailing list archives

Re: Pluggable Coherent DWDM 10Gig


From: Tim Durack <tdurack () gmail com>
Date: Fri, 25 Apr 2014 18:44:08 -0400

I'm trying to build "colorless" "directionless" with passive power
couplers/splitters plus EDFA. DTAG are doing it with 100G. I think it's
doable with 10G. Will see. Interesting experiment either way, right?

(I'm betting DTAG would use integrated pluggables if they could. They don't
appear to be fans of traditional systems.)

On Friday, April 25, 2014, Phil Bedard <bedard.phil () gmail com> wrote:

What are you trying to do?  Why do you need the receive side to be tuned
to a specific narrowband wavelength?  Coherent doesn't really make sense
in 10G becaue 10G long-haul is still on/off keyed and doesn't care about
phase. Coherent detectors are needed where phase of the signal is
important like long-haul 100G where multiple analog photonic signals are
mixed on the transmit side.  It also requires DSPs to process the received
information. You aren't going to put a DSP inside a SFP+ cage.  With
CFP2/CFP4/QSFP28 the optics vendors would like people to start building
the DSP onto line cards, whether it be a router or transport shelf,
because there just isn't the packaging room to make it happen.

Terastream today doesn't use integrated router optics, they use Cisco's
nV-Optical solution. The connection between the router and transport shelf
is still gray optics, but the system is managed as a single logical
entity, with a 1:1 correlation between router port and transponder.  You
"tune" the wavelength on the router because of the 1:1 correlation.
Terastream just uses passive DWDM muxes/demuxes, also part of the same
Cisco transport solution, and Cisco VOAs/amps.

-Phil



On 4/25/14, 2:59 PM, "Tim Durack" <tdurack () gmail com <javascript:;>>
wrote:

On Mon, Apr 21, 2014 at 2:42 PM, Tim Durack <tdurack () gmail com<javascript:;>>
wrote:

Anyone know if pluggable coherent DWDM 10Gig optics exist? (I'm finding
no
such thing.)

How about narrow-band/filtered receive 10Gig optics? (Inline FBG filter
receive side might be doable?)

--
Tim:>

p.s. Before you ask, DTAG Terastream has got me thinking...


As a follow up, there are lots of people willing to sell various flavours
of DWDM optics, but as I suspected, there is no such thing as a
coherent/tuned/filtered receive 10GigE DWDM optic. All 10GigE optics are
wide-band receive. However, you can get inline optical filters, Santec
OFM-15 for example. Investigating...

--
Tim:>




-- 
Tim:>


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