When to use CWDM and DWDM?

[jwbensley]

Hi all,

My understanding is that you would use "generally" DWDM to get more channels than CWDM, because CWDM is slightly less accurate than DWDM so the optics are cheaper.

I only need two channels to start with, but 10Gbps, for this reason do I need to deploy a DWDM mux rather than CWDM mux with an eDWM mux attached?

Extra info;

Single dark fibre between two sites. I want Fibre Channel at 1Gbps and Ethernet at 10Gbps between the two sites. This is not FCoE. Is it best to use DWDM here, and also could anyone recomment the products I would need to do this?

Many thanks,

J.

[Tom Randstrom]

The eWDM solution will not work in your application because it requires two fibers to connect the endpoints; whereby you indicate having only one fiber.  There are single fiber WDM systems on the market from other companies. . 

You will have to research whether the switches you plan on using support CWDM transceivers at 10Gbps (I do not see any Cisco 10G CWDM transceivers listed; only DWDM).  There are always transponder solutions to convert the optical output from any standard Grey wavelength to CWDM, but this will add more cost and more equipment.  It might be better to stick with DWDM transceivers.

[jwbensley]

Hi Tom,

Many thanks or your response. Bad choice of words on my part, I ment a single fibre pair, not single strand

Basically I want upto 4x 10Gbps ethernet links over this dark fibre. I think the eWDM box (EWDM-OADM4) by cisco [1] is the cheapest way forward, but do I have to use it with the CWDM box (CWDM-MUX8A), or can I just use the eWDM box on its own?

Many thanks,

J.

[1] http://www.cisco.com/en/US/prod/collateral/modules/ps5455/product_data_sheet0900aecd806a1c36.html

[Tom Randstrom · Accepted solution]

J,

There is nothing preventing you from using only the eWDM filter supporting 10Gbps DWDM wavelengths.  It would probably be best to install the EWDM-MUX8 at each end to allow for some future growth versus the OADM-4.  You can always add the CWDM filter if you wanted some additional "low-bandwidth" 1Gpbs links. 

You didn't mention what the distance was between facilities?  The data sheet indicates 80km for 10G unamplified installations and 100km using the optical amplifier. 

Good luck!

Tom

[jwbensley]

Hi Tom,

Thank you for the information you have provided. The two DCs are 10Km apart so there should be no problems there.

Also, yes I had concidered getting the CWDM-MUX8A anyway for future proof and/or an EWDM-MUX8 but it depends on the additional cost, as always

Many thanks!

[Eduardo Lucas]

I have an extra question related to this topic... is it posible to add 10GE links over our existing Cisco CWDM network?

We have two datacenters connected with CWDM-MUX8A= <---> CWDM-MUX8A=, and some CWDM channels have not been used yet; is it possible to use one or two of those channels with 10GE (ie using Cisco CWDM 10 Gigabit Ethernet SFPs like for example CWDM-SFP10G-1570= )?

Does the CWDM-MUX8A= (or the rest of CWDM family modules) allows the use of 10GE SFP?
Does it have any compatibility issues with 10GE?

[Tom Randstrom]

CWDM filters are not speed sensitive, so you can mix lspeeds across the wavelengths.  However, link length at 10Gbps is shorter than at 1Gbps so make sure the 10G interfaces support the link loss of your installed CWDM-MUX network. 

[INGENIERIA Y CONSULTORIAS WEBREDES LTDA]

Tom, the info you'll do is incorrect, the 10Gig Link is limited always at 80Kms, even amplified, that's limited by chromatic dispersion, so if you want to archive longer distances you must attach a second OAD plus an optical amplifier.

http://www.cisco.com/en/US/prod/collateral/modules/ps5455/product_data_sheet0900aecd806a1c36.html

Below Image 7

"In unamplified point-to-point links, 1-Gigabit DWDM traffic can typically achieve distances around 80km, and 10-Gigabit DWDM traffic can typically reach 60km. In amplified point-to-point links, 1-Gigabit DWDM traffic can typically achieve distances between 100 and 120km, and 10-Gigabit DWDM traffic can typically reach 80km (limited by chromatic dispersion)."

best regards.

WebRedes

[Tom Randstrom]

I've edited my response for accuracy.  Thank you for catching my error!

[INGENIERIA Y CONSULTORIAS WEBREDES LTDA]

please tom, rate if my post was usefull!