[c-nsp] DWDM Passive or Active Multiplexing

Josh Karki joshuskarki at gmail.com
Wed Mar 9 16:34:40 EST 2016

Hi Tim, thanks for your great info! Appreciate it.

Hey Bill, thanks for your offline email and confirming that the passive
DWDM should work in our environment. All great info!!

Our ring is east and westbound within 30km and in between, we currently
have like 6 drops active and looking to add another 4 drops on it. Yeah, I
know when we add site, it will loses some dB, but I guess we should be
I am going back to Cisco SE and his technical team and have a debate about
Passive vs Active again. Since they are forcing me to go with Active
solution only.

Thanks again!


On Tue, Mar 8, 2016 at 11:41 AM, Tim Rayner <Tim.Rayner at aarnet.edu.au>

> 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.
> http://www.cisco.com/c/en/us/products/collateral/optical-networking/ons-15200-series-dwdm-systems/data_sheet_c78-727050.html
> 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:
> https://www.flexoptix.net/en/produkte/transceiver/10-gigabit-cwdm-sfp-transceiver-70km-sm-ddm-dom.html
> 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
> Regards
> Tim.
> Tim Rayner
> Optical Engineer, AARNet Pty Ltd
> street address: Building 9, Banks Street, YARRALUMLA  ACT  2600
> postal address:  GPO Box 1559, CANBERRA   ACT   2601
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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
> max.
> 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.
> Josh
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