Expand Network Capacity of Existing CWDM Network across 48 Kilometers


Hybrid DWDM and CWDM networks can maximize the use of existing infrastructure to support more wavelengths. One of our clients, an IT service company, asked FS team to build a DWDM over CWDM network to expand their 48km transmission and add new links over the same WDM system.


The company wanted to connect 40CH DWDM MUX to 8CH CWDM MUX with 1530nm for network expansion. But the challenges are:


1. 40CH DWDM MUX can not be deployed in the system because of the bandwidth restriction.


2. How to add new sites to the link?


3. How to reduce optical loss and ensure enough margin over the whole link?


FS technical team planned to deploy 8CH C53-C60 DWDM MUX instead of 40CH DWDM MUX over the 8CH CWDM MUX with 1530nm wavelength to build the hybrid DWDM and CWDM network. Two CWDM optical add-drop multiplexers (OADMs) will be deployed for adding and dropping signals from new sites.

Note that, when the 40CH DWDM MUX is directly connected to the expansion port of the 8CH CWDM MUX, DWDM signals (C53-C60 and C27-C42) will be downloaded by the port with 1530nm/1550nm wavelength of CWDM MUX at site A. This means the signals from site A will not be delivered to site B. Thus, 40CH DWDM MUX can not be deployed.

Connect the 8CH C53-C60 DWDM MUX to the 1530nm port of the CWDM MUX. The other port with 1550nm wavelength of the CWDM MUX can be used for transmitting 1CH CWDM signals, or it can be connected with a 16CH C27-C42 DWDM MUX for 16CH DWDM transmission based on the actual demand.

Add one 1CH east and west OADM at the nodes of 12km and 36km respectively. The OADMs are able to add or drop new wavelength channels from the new site C and D to the existing WDM system, and this will not affect the whole link. In this case, there will be two wavelengths (1470nm and 1490nm) used for adding/dropping wavelengths at site C and D. And the two sites will communicate with site A and B respectively.

In this solution, 80km 10G SFP+ transceivers will be deployed at the four sites. The optical loss over the whole link is ≤12.6dB except for the insertion loss of all equipment, and there will be 3dB for margin.



This hybrid DWDM and CWDM network solution designed by FS technical team helps our client expand their current network capacity, and offers a flexible way to add new sites for the existing link without affecting the whole link, which will reduce the networking cost and maximize ROI. Learn more about FS DWDM/CWDM hybrid solution here.

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