How to Realize Long Distance 40G Network With DWDM Solution

Nowadays, many customers are in need of better data storage capacity and long-distance transmission. Faced with this phenomenon, FS has developed DWDM series products such as DWDM Mux, OADM, OEO and so on. And FS is always committed to meeting the specific needs of our customers and providing customized DWDM solutions for them. Currently, one of our customers from the NineStar Connect company is faced with a problem of long-distance data transmission and asks FS for help. Let’s see how FS company tackles this problem with DWDM solution.

Background

As mentioned above, this customer is seeking for solution for longer distance transmission. This customer wants to realize 48km transmission, while the maximum transmission distance of 40G QSFP+ optics is limited to 40 km and each 40G interface requires a dedicated fiber between sites. Besides, this customer told FS that their network has a dark fiber linking two sites beyond 40km, but they don’t know the link loss between these sites. Faced with this problem put forward by the customer, FS has designed a DWDM solution to meet this specific need. In the following part, detailed information about this solution will be elaborated.

What Is This DWDM Solution？

From the above topology, we can see that one 40G SR4 QSFP+ transceiver installed on the 40G switch is connected with four 10G SR transceivers by MTP-LC harness cables. So one 40G optical signal can be divided into four 10G signals in this way. In the next step, 10G DWDM SFP+ transceivers on the OEO repeater will be connected with DWDM Mux/Demux for wavelength division multiplexing. And then the optical power will be lowered by using an optical attenuator. And the dispersion will be compensated by DCM. When this process is finished, the booster amplifier (BA) will improve the optical power and extend the transmission distance. In the next step, we need to amplify the signal by using the pre-amplifier (PA) and then OEO converts the signal to the corresponding DWDM wavelengths. And then the 8ch DWDM Mux/Demux will multiplex different wavelengths of 10G DWDM signals into one fiber and then the signal is transmitted to Site B. Finally, 40G QSFP+ transmission distance can be extended up to 80km in this way.

Why Choose This Solution?

After reading the above introduction of this solution, you may want to know more about its advantages. Here are some reasons for choosing this solution.

Network Capacity Expansion

In this solution, we use MTP-LC harness cables to divide 40G optical signal into four 10G signals and then use an OEO to convert the optical signal into DWDM wavelengths with a transmission distance up to 80km. In this way, we can significantly reduce cost and increase the capacity of the whole network without changing the customer’s existing cabling infrastructure. And we choose 8ch DWDM rather than 4ch DWDM because 8ch DWDM has 4 vacant channels for later network expansion. In addition, using 8ch DWDM duplex bi-directional transmission mode can support 2×40G transmission capacity.

Low Link Loss

In this solution, the expectant optical power of DWDM 10G 80km optical module is 23dB, and the insertion loss of 8ch Mux is 3.5dB. In order to realize better signal transmission, the single-wave output power of BA (Booster Amplifier) needs to be controlled below +8dB, and the single-wave input power of PA (Pre-Amplifier) needs to be controlled above -25dB. This solution can be better used in network link whose link loss is 29-33dB because when the link loss is up to the maximum value of 33dB, there still has a 3dB system margin.

Efficient Equipped Optical Products

FS provides some cost-effective optical products in this solution, including OEO, DCM, PA and BA. These products play different roles in this DWDM solution. The optical power will be lowered by using an optical attenuator in the process of transmission so as to avoid damaging the transceiver. And the use of DCM can compensate for the dispersion in optical transmission. OEO can convert four 10G signals into corresponding wavelengths, which can amplify the optical power in the solution. PA is deployed before the optical receiver so as to amplify the weak optical signals and BA is placed in front of the optical fiber line in order to improve the optical power. Equipped with these optical products, the capacity of the whole network can be improved dramatically.

Conclusion

This solution will be an ideal option for customers who are in seek of 40G long distance transmission. FS is always striving for meeting your specific requirements. If you are interested in this DWDM solution or have the same problem with this customer, we hope this post can offer the reference for you.