Tag Archives: DWDM SFP+

Tunable SFP+ VS. Fixed Wavelength DWDM SFP+ Transceiver

Dense wavelength division multiplexing (DWDM) is one of most important technologies to increase network transmission capacity. Early DWDM systems applied fixed wavelength DWDM transceivers and performance is good. However, as the demand for great traffic capacity keeps growing, more optical transceivers of different wavelengths are needed, leading to high cost. So how to deal with that? Tunable SFP+ arises your attention.


What Is Tunable SFP+

Conventional DWDM SFP+ transceivers use fixed-wavelength lasers as light sources. It means that many optical transceivers are needed for the wavelength channels in a DWDM system. While tunable SFP+ is different from fixed wavelengths modules because it applies tunable laser, which can operate at any channel wavelength, means that only one kind of transceiver is needed. Tunable lasers are now widely used as light sources in DWDM systems. Tunable SFP+ modules are only available in DWDM since CWDM grid is too wide. Tunable SFP+ optics are for the C-Band 50GHz. About 88 different channels can be set with intervals of 0.4nm, which is the 50GHz band.

For better understanding, I’ll show you a tunable module. This is a Cisco Compatible 10G DWDM C-band tunable SFP+ 50GHz Transceiver. It’s hot swappable, can support 10.3Gbps data rate up to the distance of 80km over single mode LC duplex fiber patch cable. Support 1563.86nm-1528.77nm C-band tunable wavelengths.

Cisco-tunable-SFP+ optics

What you should note is that wavelengths of tunable SFP+ can be tuned only when your Cisco/Juniper/Arista/etc switch supports. If your switch only support common fixed-wavelength DWDM SFP+, you need external software to change tunable optics into certain wavelength before putting into use.

Why Tunable SFP+ Is Better Than Fixed Wavelength SFP+?

Fixed wavelength SFP+ are still in the market and not too many problems found in use. So you may feel puzzled about choosing tunable SFP+ or fixed wavelength SFP+ as tunable SFP+ is more expensive. The following will tell you why you need tunable optics.

First, save you cost. With the development of optical communication systems, the shortages of fixed-wavelength laser gradually revealed. Conventional DWDM SFP+ can lead high costs. The number of wavelengths in DWDM 50GHz has reached the hundreds. Then spare modules of each laser should be prepared for protection of the system because you don’t know which module will break down and it’s difficult to predict the number of stock in specific channels. Therefore you have to buy large quantity of DWDM SFP+ modules with fixed wavelengths. While the tunable optics are configured with different DWDM wavelengths in one module. You can select the right wavelength you need based on your optical fiber communication environment. Tunable SFP+ are typically used as “spare-optics” to save you cost.

Second, flexible network management. When running a DWDM network with lots of nodes, for instance, up to 80 different wavelengths, management could be a nightmare. You have to prepare couple of DWDM SFP+ optics of each wavelength and possibly in different locations. Field engineers may not access network nodes as quickly as you wish. Thus tunable optics would be a good choice. Tunable optics could be configured for a specific wavelength to support bandwidth changes as needed in optical network.

Third, suitable for large network capacity. As the development of increasing network transport, 400G or 1T would be the trend. Then 400G and 1T transmission formats are expected to be bulky and not fit within 50GHz spacing. These future new data rate formats require that channel spacing is flexible, that your OTN system can adapt to new rates and can re-arrange channel spacing to find place for new rates in it. Tunable optics will double the number of channels supported in this transceiver module. Upgrading to 50GHz channel spacing doubles the capacity potential in Enterprise and Metro networks.

Choose Tunable SFP+ in the Long Run

Tunable SFP+ are high-performance optics which can be tuned to the appropriate wavelength in seconds. The ability to function on various wavelengths has set these optics apart from fixed-wavelength DWDM SFP+. Tunable SFP+ will become popular among DWDM systems due to their ease of spare use and flexibility. Tunable SFP+ would be a powerful and invaluable transmission tool in high-speed network. At present, many engineers are using fixed wavelengths SFP+ transceivers. Some may be stopped by the tunable SFP+ price. But in the long run, you are suggested to consider tunable SFP+.

How to Extend 40G Connection up to 80 km?

As 40G connectivity is accelerating, many data centers prepare to migrate from 10G to 40G. But the link distance between 10G and 40G switches is a big challenge. This article can help you extend 40G connection distance.

Current 40G QSFP+ to 4x10G Connection—Max 10 km

As we know, 40GBASE-SR4 QSFP+ is designed for short distance of up to 150m connection. 40GBASE-PLR4 QSFP+ can support long distance link of up to 10 km. Both 40G QSFP+ modules are interfaced with 12-fiber MTP/MPO and can break out into 4x10G connection. To build 10G-40G connection, for instance, using singlemode 8-fiber MTP-LC harness cable to connect 40GBASE-PLR4 QSFP+ and 4x10G SFP+ modules. As the direct connection distance between two 40GBASE-PLR4 QSFP+ optics can reach at most 10km, it’s easy to understand that the connection between 10G and 40G may be shorter. However, we provide a method to extend 40G connection to 80km distance. Continue to read this article and find the answer.

10km max

Equipment for Extending 40G QSFP+ Connection

To extend 40G QSFP+ connection distance, we have to use WDM transponder OEO (Optical-Electrical-Optical) repeater. OEO repeater allows connection between fiber to fiber Ethernet equipment, serving as fiber mode converter, or as fiber repeater for long distance transmission. It can also function as CWDM/DWDM optical wavelength conversion. Now we will use a multi-service transport system, including a hot-swappable plug-in OEO card which only occupies 1 slot. The other space can be left for holding more cards such as DCM, EDFA, OLP. On the left side, there is a card for centralized network management.

WDM transponder oeo

This is a 4-channel multi-rate WDM transponder with an OEO-10G card containing 8 SFP/SFP+ slots and can support up to 11.3G rate. The OEO card can convert 1G~11.3 Gbps Ethernet signals into a corresponding wavelength in CWDM and DWDM network infrastructures. Transmission distance can reach 80 km.

Except WDM transponder OEO repeater, we still need DWDM Mux/Demux and DWDM SFP+ to extend the distance to 80 km. DWDM Mux/Demux is to combine 4x10G signals of different wavelengths on one single fiber so that it’s the best solution to increase network capacity and save cost. Here we use 40-channel C21-C60 dual fiber DWDM Mux/Demux. So we can choose suitable 10G DWDM SFP+ modules 80km transceiver between the wavelengths of C21 and C60.

For your reference, the equipment for 40G connection extension mentioned above are from FS.COM. You can select those of other specifications according to your own needs.

Equipment Details
Fiber Transceiver 40GBASE-PLR4 QSFP+ 1310nm 10km MTP/MPO Transceiver
Generic Compatible 10GBASE-LR SFP+ 1310nm 10km DOM Transceiver
C21-C60 DWDM SFP+ 80km DOM Transceiver
Transponder Repeater 4-channel WDM transponder OEO repeater
DWDM Mux/Demux 40 Channels C21-C60 Dual Fiber DWDM Mux Demux with Monitor Port, 3.0dB Typical IL
Extend 40G QSFP+ Connection to 80 km

Install 40GBASE-PLR4 QSFP+ into QSFP+ port of a switch and 4 10GBASE-LR SFP+ into the Ethernet ports of the WDM transponder OEO repeater. Then plug a singlemode 8-fiber MTP-LC harness cable to connect 40GBASE-PLR4 QSFP+ and 4 SFP+ modules. Because of the OEO repeater function, 4x10G Ethernet signals are converted into corresponding wavelengths in DWDM network infrastructure. Then install 4 x 10G DWDM SFP+ transceivers into other four ports of OEO repeater. Next step is to connect DWDM SFP+ modules on the OEO repeater and DWDM Mux/Demux by using LC duplex patch cables. In this way, 40G QSFP+ distance can be extend up to 80 km.



10 km transmission distance is not the limit of 40G to 4x10G connection. From this article, you can extend 40Q QSFP+ to 80 km by mainly applying WDM transponder OEO repeater, DWDM Mux/Demux and 10G DWDM SFP+. If need to break your network distance limit, please visit our site www.fs.com or contact us via sales@fs.com.

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Economically Increase Network Capacity With CWDM Mux/DeMux
Check out All CWDM Transceiver Modules
User Guide for CWDM MUX/DEMUX