Question about DWDM Transceiver

[Zhomart Asken]

Hi everyone!

Wanted to know something about DWDM technology. For example, if we use 10G SFP+ DWDM transceiver, does it mean that it can handle multiple 10G channels? Up to what speed and distance it can practically provide?

Thanks!

[Marvin Rhoads · Accepted solution]

A given DWDM transceiver (Cisco or otherwise) only handles a single 10 Gbps channel at at time.

Cisco offers two general types - fixed and tunable. All the various models are shown on the data sheet here:

https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/dwdm-transceiver-modules/data_sheet_c78-711186.html

With fixed you decide which channel you require for the transceiver and specify it when purchasing. Tunable allows you to control the wavelength via software configuration on the router. See the following discussion for some more info on that feature:

https://supportforums.cisco.com/t5/optical-networking/dwdm-sfp10g-c-tunable-optic/td-p/2684243

As far as distance, the transceiver capabilities are based on your optical link loss budget and some other factors such as dispersion. As transceivers, they are used on the input of a DWDM system and typically intra-data center if not intra-rack. The output is the link where distance generally comes in to play. It's something you would need to work with your SE on to get a detailed and verified answer. Since these cost about US$20,000 per transceiver (list price), it's something you want to enter into only after due diligence.

[Zhomart Asken]

Ok thanks.
On Cisco site there is a statement: "The DWDM XENPAKs can be used for un-amplified and amplified designs to transmit upto 320 Gigabit over the same pair of SMF." How a fiber channel can transmit up to those speeds if it is connected to a single 10G transceiver?

[Marvin Rhoads · Accepted solution]

That's what's know as "marketing math". It works something like this:

Populate your routers with 32 transceivers all on different channels feeding a DWDM system. The DWDM has 32 input channels and one aggregated output. 32x10 = 320 Gbps.

[Zhomart Asken]

Ok now I understand how it works. Thanks
And do we need transceivers on the side of DWDM system's input?

[Marvin Rhoads]

Regarding DWDM inputs, there are many forms. Depending on the DWDM system they can be as low speed as copper T-1/E-1 inputs.

When talking about 10 Gbps Ethernet inputs, yes they will generally be transceivers matching the input specifications of the given DWDM system. The overall system usually has a fair amount of complexity and Cisco (and its resellers) offer design validation services to get all that straight during the planning and design phase.