Case Study: 16CH DWDM to Realize 4x10G over 460km

Updated on Jul 8, 2018 by

Our customer is going to design a long-haul 4x10G OTN network project using single mode fiber beyond 465 km, actually nearly 500 km, as shown in the following figure. Link loss is 0.3 dB on per KM. Site 1, 2 & 6 are AC powered sites. Site 3, 4 & 5 are DC Powered sites. AC and DC power are available on both DC1 & DC 2. The network switches they use include Cisco WS-C4500X-16, Cisco WS-C4500X-32, Huawei S6720-54C-EI-48S-AC, Huawei S5720-56C-EI-48S-AC, Juniper EX4550-32F. Customers' requirements are:

 First, they need redundancy on OTN network and build a connectivity between DC1 & DC2 as well.
 Second, considering future network expansion, they need 4 - 8*10G channels. They will be adding one more 10G handoff on each site.
 Third, since there are so many sites over the link, remote configuration management would be better.
Multinet challenges


For current network transmission

Currently 3CH signal is transmitted from DC1, and 1*10G signal is downloaded in Site 1, 2, 4 respectively. No network capacity expansion in Site5/6 is needed.

16CH DWDM OTN Project

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 DWDM Mux/Demux to increase network capacity

16 channel DWDM system is recommended for this long-haul transmission project. 16 Channels Single Fiber DWDM Mux/Demux would be perfect. To connect DC1 and DC2, 3*8CH CWDM mux/demux which are more cost-effective are useful. Single fiber or dual fiber system are available and it depends on customers' actual needs.

 OADM for network expansion

3CH signal is transmitted from DC1, and 1*10G signal is downloaded in Site 1, 2, 4 respectively. So Site 1 and Site 2 use 2CH east and west OADM so that the other channel can meet the future network upgrade needs.

 Site3/4 as regeneration station

Due to the long haul network of more than 465 km, FS.com EDFA is suggested to achieve signal amplification due to its low-noise and insensitive to signal polarization. And Site 3 and Site4 would be regeneration stations. OEO will be employed as only DC power is supported there.

 Ensure optical power balance

In real connection, attenuators would be applied to debug optical power performance & fiber signal attenuation to ensure the optical power balance. As fiber optical loss is 0.3db/km, the Input Power of all Pre-amplifier are controlled below -25dB with the Safety Margin of at least 3dB.

For future network capacity expansion

1CH east and west OADM can be applied in Site 5/6 when business capacity expansion is required in the future.

1CH east and west OADM

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Solutions Advantages

 The whole network shares a set of management systems to realize the unified management of the devices of each station, and realize the real-time remote monitoring and fault alarming.
 Achieve ultra long distance and large bandwidth business transmission.
 The site configuration is relatively flexible and easy to maintain.


Considering the network capacity expansion and fulfilled its long-haul OTN project which carries huge loads of information under various sophisticated situations, solution two is better. Challenges of reducing signal loss has been overcome. All network sites apply the same remote configuration management system which can realize timely control and failure alarm. It offers flexibility and simpleness for network maintenance.

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