Tag Archives: CWDM OADM

Examples of CWDM Network Deployment Solution

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Based on the same concept of using multiple wavelengths of light on a single fiber, CWDM and DWDM are two important technologies in fiber optical communications. As we all know, although the transmission distance of CWDM network is shorter than that of DWDM, it costs less and has the scalability to grow fiber capacity as needed. This article intends to give a simple introduction of components in CWDM networks and to explore some examples of CWDM network deployment cases.

Common Components Used in CWDM Networks
CWDM Mux/Demux

CWDM Mux/Demux, which is based on the film filter technology, is the basic component in CWDM networks. It can combine up to 4, 8 or 16 different wavelength signals from different fiber extenders to a single optical fiber, or it can separate the same wavelengths coming from a single CWDM source. That’s why CWDM can extend existing fiber capacity.

CWDM OADM (Optical Add-Drop Multiplexer)

A CWDM OADM is a device that can add (multiplex) and drop (demultiplex) channels on both directions in a CWDM network. It can add new access points anywhere in CWDM systems without impacting the remaining channels traversing the network. With this ability of OADM, the access points can be added to liner, bus, and ring networks, where the dual direction ring design provides redundant protected architecture.

CWDM Optical Transceiver

Optical transceiver is a necessary element in optical networks. And CWDM optical transceiver is a type of module supporting CWDM network application with CWDM wavelengths. When connected with CWDM Mux/Demux, CWDM transceiver can increase network capacity by allowing different data channels to use separate optical wavelengths (1270nm to 1610nm) on the same fiber. And the common CWDM transceiver type is SFP, SFP+, XFP, XENPAK, X2, etc.

CWDM Network Deployment Solution
Example One

Description: there are five buildings (Sheriff, Courthouse, Admin, Police & Fire, & Public Works) connected via multimode fiber cables (MMF) or single mode fiber cables (SMF). These buildings are linked via multimode SFPs in an existing D-link switches to create one network for internal use of the city offices. Below is a simple graph to show the situation.

CWDM Network 1

Requirements: the goal is to install a single mode fiber network in town to connect numerous buildings. Some of these buildings have access to the city LAN. The Public Works building need to connect with Youth & Recreation Center, Library, Immanuel Lutheran School and the Senior Center. And all these buildings should have unfiltered Internet. Besides, the Waster Water Treatment Plant should be connected passing through the Senior Center. All these services are achieved using CWDM technology.

Solution: according to the requirements, this is a CWDM networks with several buildings to connect with. Here is the solution diagram.

CWDM Network

In the diagram above, we can see there is an 8CH CWDM Mux/Demux connected with the switches. According to the requirements, Youth & Recreation Center, Library, Immanuel Lutheran School and Senior Citizen Center should be connected with the Public Works and need unfiltered services. Therefore, a 4CH CWDM OADM is placed after the CWDM Mux/Demux. Then the four wavelengths will be drop and into the four buildings. In addition, another CWDM OADM is deployed in Senior center to connect the Waster Water Treatment Plant, to meet the requirement. And each site also needs to use CWDM optical transceivers.

Example Two

Description: on site A, there are three Ethernet switches and a T3 router. And their working wavelengths 1470nm, 1490nm, 1510nm, 1530nm and 1610nm. Other three sites B, C, and D also have three Ethernet switches. And a T3 router is in site E. As the following figure shows.

CWDM OADM

Requirements: Considering the cost, all the wavelengths should be transmitted on a single fiber using CWDM technology.

Solution: according to the requirements, here is a simple diagram showing the solution.

CWDM Mux Demux

In order to save cost, a 4CH CWDM Mux/Demux is used to multiplex four wavelengths (from three switches and one router) into one single fiber. At the first site B, a 1CH CWDM OADM is installed to remove one wavelength which is associated with network B. And other three sites are the same—dropping one wavelength associated with corresponding switch or router.

Summary

This article mainly introduces two CWDM network deployment examples. All the components like the CWDM Mux/Demux, CWDM OADM and CWDM transceiver are available in FS.COM. If you are interested in them, please contact us via sales@fs.com.

Related article:Differences between CWDM and DWDM

Optical Add-drop Multiplexer Overview

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With an explosive growth in the amount of information transmission, the optical telecommunication networks develop rapidly. The progress of single wavelength point-to-point transmission lines to wavelength division multiplexed optical networks has introduced a demand for wavelength selective optical add-drop multiplexer (OADM) to separate or route different wavelength channels. This paper will have an overview of the OADM.

OADM Technology

The introduction of optical add drop multiplexers into optical networks allows traffic to be inserted, removed and, most importantly, bypassed. Moreover, OADM can support functions such as protection, drop/continue, loop-back and wavelength reuse of the optical channels. Drop and continue refer that the channel is removed at the node but allowed to pass through to the next OADM. Wavelength reuse means the dropped channel does not pass through to the next OADM, instead, a new channel of the same wavelength can be added. Below figure explains OADMs work in a CWDM system.

CWDM OADM
Passive and Dynamic OADM

OADM can be used in the dynamic as well as static mode. The add and drop wavelengths are fixed in the passive OADM, while in dynamic mode, the OADM can be set to any wavelength after installation. Passive OADM is mainly used in networks with WDM systems (CWDM and DWDM) or hubbed structures, where the OADM is connected to a central hub, e.g. in the metropolitan network. In order to utilize resources in a more efficient way, the OADM with dynamic wavelength assignment are preferred when traffic variations are comparable to network capacity. It can select any wavelength by provisioning on demand without changing its physical configuration.

Advantages

OADM has many advantages. The most striking one is that its multiplexing happens to coincide with the minimum loss area of single mode fiber. This reduces the transmission loss of the light signal which can be transmitted relatively far distance. Additionally, it is transparent to digital signal format and data rate. Its gain saturation recovery time is long, and has a very small crosstalk between the respective channels. What’s more, multiple channels of information carried over the same fiber with each using an individual wavelength. Narrow channel spacing or wavelength selection give rise to denser channels in the same wavelength range. Last but not the least, repeater or amplification sites are reduced, which results in large savings of funding.

Applications

OADM supports standard network topologies such as point-to-point and ring. It can be used at different points along the optical link to insert/remove or route selected channels increasing the network flexibility. This feature is particularly important in metropolitan WDM lightwave services where offices or sites can be connected by different add-drop channels, for instance in an interoffice ring. In WDM systems, OADM is installed in a multi-wavelength fiber span, and allows a specific wavelength on the fiber to be demultiplexed (dropped) and remultiplexed (added) while enabling all other wavelengths to pass. Then it can provide flexibility and scalability to optical networks as it allows users to optimize the use of existing fiber by adding or dropping channels on a per-site basis, thereby maximizing fiber bandwidth.

In conclusion, optical add-drop multiplexer can contribute to improve and optimize the network performance. Fiberstore, a professional supplier in the optical industry, has lots of CWDM OADM and DWDM OADM. Besides these, the WDM fiber optic multiplexer, CWDM Mux/Demux and DWDM Mux are also available. Welcome to visit www.fs.com for more information.