40G reforming

Baldur Norddahl baldur.norddahl at gmail.com
Mon Feb 5 19:03:33 UTC 2018

I may need to clarify that I do not want to break the port into 4x10G as
such. To the switch this will be an ordinary 40G link to another switch far

I want to take advantage of the fact that 40G is transported as four
individual streams. Each of the four streams are to be converted from 850
nm to a 1550 DWDM channel (one channel per stream). And the reverse at the
other end of the link.

The point of doing this is that 40G DWDM modules are not generally
available and neither are 80 km modules.

I need a true 40G channel so 4x10G LACP is not an option here. For the same
reason I am unable to accept a solution that splits the 40G port into 4x10G
and then perhaps recombines using LACP. Instead I am looking at an optical
solution that is invisible to the switch hardware.

The only doubt I have about the proposed solution is whether the frame
format of the 10G substreams is somehow incompatible with what goes on in
the reformer. As I understand these reformers they are little more than two
SFP(+) modules connected back to back. And therefore it should not matter
that the frame format may be different.



Den 5. feb. 2018 7.20 PM skrev "Paul Zugnoni" <pz at wish.com>:

Whether a 40G port can be broken into 4x10G is dependent on the
router/switch hardware and the optic you use. Good news is that most 40G
ports are capable of being broken out into 4x10G, since a 40G port is
usually operating as 4x10G internally anyway to the ASIC. The QSFP you'll
need would be a 40G-SR4 for MTP/Multimode or 40G-LR4 for MTP/Singlemode (or
a lower power, less expensive equivalent). This is a pretty common use of
40G ports. All 4 10G ports would then be at 850nm or 1310nm, which you can
then plug into any 10G SR or LR ports.

What router or switch platform is driving the 40G?

Paul Z

On Mon, Feb 5, 2018 at 7:57 AM, Baldur Norddahl <baldur.norddahl at gmail.com>

> Hello
> Is it possible to reform a 40G signal as individual 10G links?
> The idea is to use a 40G QSFP multimode MTP module such as
> https://www.fs.com/products/44058.html. Then connect it using a MTP
> breakout cable such as https://www.fs.com/products/68049.html to get four
> dual fiber connectors. These are then connected to four 10G SFP+ multimode
> modules such as https://www.fs.com/products/11589.html. The reformer
> could be https://www.fs.com/products/43721.html. And finally the reformed
> signal can be transported using anything including DWDM modules such as
> https://www.fs.com/products/44058.html.
> Just using fs.com as a reference to the kind of equipment I am talking
> about. Many other vendors offer simelar products.
> The motivation for doing this is to get access to the many options that
> are available for 10G optics but not possible with 40G.
> Regards,
> Baldur

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