Wavelength Division Multiplexing (WDM), as we discussed in our earlier blog, enables enterprises and carrier networks to maximize the capacity of the fiber infrastructure, by transferring a number of optical signals onto a single optical fiber by using different laser wavelengths.
As well as multiplying capacity, it can also enable bi-directional communication over one strand, making it a cost-effective way of expanding the network simply, without adding another fiber.
01. Wavelength Division Multiplexing (WDM) Transceivers – how they work
Optical transceivers convert the electrical data signals from the host equipment into the specific light wavelengths which are then transferred to a CWDM or DWDM Multiplexer to be carried independently and transmitted over a single fiber or fiber pair.
There are a large range of WDM transceiver options available, with specifications of up to 400Gbps and a range of up to 160km. Choice will depend on your implementation, transmission distance along with bandwidth requirements and whether you have chosen to use CWDM or DWDM.
02. CWDM or DWDM for your WDM transceiver?
Key considerations are that DWDM is generally more costly than CWDM because DWDM has more sophisticated technology (especially the laser) to achieve longer distance reach and obtain higher density and bandwidth. Consider the larger project requirements including your multiplexing solution, these are likely to determine CWDM or DWDM quite clearly.
You can read more about Coarse Wavelength Division Multiplexing (CWDM) or Dense Wavelength Division Multiplexing (DWDM) on our subject focused blog here >
03. WDM transceiver form-factor – SFP, SFP+ or QSFP28?
You will need to take the physical interface for the switch or network device that you are using into consideration.
Several industry standards ensure network equipment compatibility, and there are a range available, including SFP, SFP+, SFP28, QSFP28, or XFP. Example data transmission rates and ranges for CWDM and DWDM for the different form-factors available are given below. Note that XFP and SFP+ can both transmit up to 10 Gbit, however XFP has a bigger footprint than SFP+ transceivers and they are not interchangeable.
100M, 1G, 4G
40 – 160km
40 – 80km
8G, 10G, 16G
10 – 80km
20 – 100km
40 – 80km
40 – 80km
10 – 40km
SFP is designed to support 100/1000Mbps Ethernet, Fiber Channel and SONET/SDH and support transmission speeds of up to 4.25Gbps and ports for SFP are commonly found on Ethernet switches and routers, NIC cards and firewalls. SFP+ is almost identical to SFP but supports faster speeds of up to 10Gbps over a longer distance.
QSFP (quad small form factor) also supports Ethernet, Fiber Channel and SONET along with InfiniBand and can transmit at different data rates, with QSFP28 being one of the most recent versions supporting 100 Gbps applications. QSFP can support 4 x 25Gbps channels, 2 x 50Gpbs or 1 x 100Gbps depending on the transceiver.
04. Select the right CWDM or DWDM wavelength
A transceiver is selected for each channel and they are color-coded to an industry standard for each frequency.
Let’s take a look at selecting for CWDM as an example. Typically, a CWDM multiplexing system can transmit 18 channels at frequencies ranging from 1270nm to 1610, at 20nm apart. The chart above shows the industry standard for the different CWDM frequencies. To allow for a longer transmission range, CWDM SFP modules, for example, support 8 frequencies from 1470nm to 1610nm.
DWDM, used to provide high-capacity bandwidth, can carry 40 wavelengths at 100 GHz spacing, often referred to in terms of the wavelength, with a range of 1588.77 nm to 1563.86 nm with channel spacing of approximately 0.8nm. Alternatively, 50 GHz, 25 GHz spaced grids and tunable grids are also available allowing for up to 96 channels. So when selecting, this should be borne in mind.
05. WDM Transceivers – Compatibility across multiple vendors
Finally, the Multi-Source Agreements (MSA) also enable you to mix and match modules from different manufacturers and ensure compatibility, with Pro Optix transceivers to match your particular installation, from Brocade and Cisco, through to HP and Huawei. Check out our portal or give us a call to find the right transceiver for your application.
If you would like support for a WDM project please contact the Pro Optix specialist team – our WDM solutions are utilized in 4 of the top 5 service providers in Sweden.
Our comprehensive portfolio of fiber optical networking solutions enables us to offer our customers a solution tailored to their specific network demands.
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