DWDM Mux/Demux using 40G Optics

Faisal Imtiaz faisal at snappytelecom.net
Mon Jun 19 19:01:45 CST 2017

Answers in-line below.

Faisal Imtiaz
Snappy Internet & Telecom
7266 SW 48 Street
Miami, FL 33155
Tel: 305 663 5518 x 232

Help-desk: (305)663-5518 Option 2 or Email: Support at Snappytelecom.net

----- Original Message -----
> From: "Colton Conor" <colton.conor at gmail.com>
> To: "nanog list" <nanog at nanog.org>
> Sent: Monday, June 19, 2017 2:26:55 PM
> Subject: DWDM Mux/Demux using 40G Optics

> We are building a 40G metro ring using 40-Gigabit Ethernet QSFP+
> Transceivers. Specifically, we are using Juniper JNP-QSFP-40G-LR4. This is
> a QSFP+ Transceiver with a LC duplex head. We only have one pair of single
> mode dark fibers around the ring.  Our distance between nodes around the
> ring are all less than 10KM, so we can use standard optics.
> We go out of one JNP-QSFP-40G-LR4 and into another JNP-QSFP-40G-LR4. There
> are no passive muxes involved. This is working great for 40G.
> My understanding is a JNP-QSFP-40G-LR4 is really a transceiver with a CWDM
> mux built into it. The spec sheet shows it sends 4 10G channels:
> https://www.juniper.net/documentation/en_US/release-independent/junos/topics/reference/specifications/optical-interface-qfx-support.html
> Lane wavelength
> Lane 0–1264.5 nm through 1277.5 nm
> Lane 1–1284.5 nm through 1297.5 nm
> Lane 2–1304.5 nm through 1317.5 nm
> Lane 3–1324.5 nm through 1337.5  nm

YES this is correct and goes for pretty much all of the SMF QSFP+ 40g Optics. (they utilize 4 cwdm channels) 

> This setup is working fine, but now we want to do more than 40G around the
> ring. To my knowledge there are no other 40G QSFP+ transceivers that use
> four other channel/lanes than the ones already being used, so they only way
> to go higher than 40G is to stack 10G or 100G channels ontop of the fiber
> pair using a passive mux.

Typically you would stack 40G + 10g Channels or 100G+10g Channels
(100g optics would be using 4 channels as well).

> 100G is too expensive for the time being, so we are looking to add 10G
> channels to a ring that already have one 40G channel using the QSFP+.

Yep, that would be the cost effective way to do it.

> I was reading this tutorial, and it mentions "there is a 1310 nm port
> integrated in a 40 channels DWDM Mux/Demux system. The 1310nm added port is
> a Wide Band Optic port (WBO) added to other specific DWDM wavelengths in a
> module. When we run out of all channels in a DWDM Mux/Demux system, we can
> add the extra optics via this 1310nm port."
> http://www.fs.com/upgrade-to-500g-with-40ch-dwdm-mux-demux-system-aid-493.html
> What I can't seem to understand is they are mentioning that this 1310 port
> can pass QSFP+ signals, so it sounds like its really a 1270nm through
> 1330nm port? Is this what they mean by   Wide Band Optic port (WBO)?

Yes that would be correct, 1310nm is simple nomenclature when used with 40g/100g QSFP+ SMF optics

> We don't need 40 10G channels plus a 40G for a total of 440G. More than
> likely we are looking at a 8 channel mux/demux, and 1 40G port for a total
> of 120G.
> I don't care if we do CWDM vs DWDM, but I assume it will be hard to find a
> CWDM mux that has one LC dupluex input for  1270nm through 1330nm channels?

If you  look at the CWDM Muxes (8 or 9 channel) you will notice a common configuration of

    Upgrade Port (expansion port)  + 1450 or 1470 to 1610nm 

    in the DWDM muxes you will see  them listed as # of Port + 1310 pass thru channel.

These are exactly what you are looking for ..... :) 

> Maybe I should just ditch the 40G QSFP+ optics and use all 10G optics, but
> the switches I am using have 48 10G SFP+ ports and 6 QSFP+ ports built in.
> I know there are 40G breakout cables, but the whole point of 40G is to
> aggregate VLAN/circuits.
> Has anyone done this before?

Am in the process of lighting a number of locations in this manner...

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