[c-nsp] DWDM Passive or Active Multiplexing

Tim Rayner Tim.Rayner at aarnet.edu.au
Tue Mar 8 14:41:01 EST 2016

Hi Josh,

We run lots of passive CWDM and DWDM as well as DWDM ROADMs.

If you're happy with passive in you current solution, I'd suggest staying passive.  We have passive 10G CWDM and DWDM solutions running well over 30km.

We have used the Cisco CWDM & EDWM solution - it is an easy way to get another 8 channels without impacting any of your existing ones (apart from the outage to all wavelenghts whilst you insert the EWDM muxes at each end).  There is also the Amplifier option for the 8 DWDM channels if you need an extra bit of range - though that little Amp module may be end-of-life from memory - perhaps no-one was needing it.

What we prefer to use these days is some small 4-channel DWDM muxes within the  1530 or 1550 bands of the CWDM channels.  These Cisco models can be cascaded to give 8 or 12 DWDM channels within the CWDM 1550 channel.

It does mean that you need to free up your CWDM-1530 or CWDM-1550 channel before you can add more services, but we find these are much more flexiible setup than the CWDM/EWDM combination.  This is especially true since we have some CWDM Add/Drop muxes spliced into pits to connect tail circuits to a trunk.

Also, keep in mind that even though Cisco may not have good support for 10G optics in the 8 regular CWDM channels, other vendors do and give Cisco compatibility - for example:

Depending upon your migration strategy, you could leave your passive muxes unchanged and just make the switch to 10G CWDM optics.

I hope this helps 



Tim Rayner
Optical Engineer, AARNet Pty Ltd
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From: cisco-nsp [cisco-nsp-bounces at puck.nether.net] on behalf of Josh Karki [joshuskarki at gmail.com]
Sent: Wednesday, 9 March 2016 6:16 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] DWDM Passive or Active Multiplexing

We are working with Cisco to replace our passive CWDM with DWDM ring
network. The goal here is to upgrade 1G CWDM with 10G. The current CWDM
ring with use of all (8) wavelengths within 30kms is working just fine.
It's a passive solutions and I don's see any powering issues with it.

When we upgrade it to DWDM, the distance for max connection will still be
the same, max 30 kms, but we may add more sites or we go up to 12 channels

I see the option of E-WDM, 8 more wavelengths on top of 8 existing CWDM'
but this is not what we are looking to move forward with.

Now my questions is, DWDM Passive vs Active. With such environment, can it
be possible to do Passive DWDM instead of of Active?

Thanks for your advice.

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