100G Connectivity for Metro Network

The Metropolitan Area Network (MAN), often referred to as a metro network, connects multiple Local Area Networks (LANs) within a metropolitan region. It has evolved over the years and continues to be upgraded to accommodate high-speed services. As one of the most common applications of 100G networks, let's explore the features of today's 100G metro networks and the available connectivity solutions for MAN networks.

Basics of Metro Network: Common Scenarios and Types

The cover range of metro networks can be different, some as small as several kilometers and some as large as a couple of hundred kilometers. Generally, the distance that MAN covers is around 5 to 50km.

Metro networks are not tied to a specific organization. Ownership of metro networks can be either private or public. These networks can range from individual connections, such as a wired Internet service for television, to extensive networks formed by connecting multiple LANs.

The common metro network scenarios are as follows:

• Metro network can be used by a company that has different buildings in separate areas within a city. By forming a metro network, these buildings are connected through optical fibers to make the organization work flawlessly.

• Another common use scenario of MAN is the single city interconnected as a single MAN to provide wired or wireless connections to the city residents.

• And also there are telecom companies that rent fiber connections in a city. Businesses use them to connect, thus forming a massive metro network.

With the development of new technology and more and more devices interconnected with each other, the use of metro networks will continue to increase. For the sake of the requirements of a bearer network for diversified services, metro network implements multi-layer construction. Typical IP MAN is divided into three layers: core layer, service control layer, and access layer. The core layer provides a high-bandwidth service bearer and transmission. To meet the exploding bandwidth over the years, a 100Gbps link is often deployed in the core layer. Until these years, as metro traffic grows fast, some carriers begin to bring 400G into MAN and 100Gbps link is expected to move to the access layer.

Approach to 100G Metro Network Connectivity

According to the different technologies that form a metro network, the metro network can be divided into three main platforms: SDH/SONET, Ethernet, and WDM.

Among these platforms, SONET/SDH is the traditional one, but it is gradually taken place by Ethernet—the original standard choice of LAN. The migration from SONET/SDH to Ethernet is because of Ethernet's simplicity, interoperability, and cost efficiencies that Ethernet features over SONET/SDH. SONET/SDH bandwidth allocation is rigid while Ethernet is flexible, providing more efficient network utilization for service providers. The advantage is more vivid especially when the emergence of 5G technology and new IoT devices drive the increase in data content. In terms of network topology, SONET/SDH networks are deployed in fixed ring-based design while Ethernet supports more types of network topologies such as ring, mesh, tree and string-based topologies. In addition, the overall cost of operation and maintenance for Ethernet networks is lower than SONET/SDH and the scalability enables easy migration to 100G and beyond.

The advantage of DWDM has been long recognized for its long-distance, ultrahigh-bandwidth transport applications. As the process of deploying optical fiber becomes time-and-cost consuming, Ethernet over DWDM becomes the optimal choice for the growth of high bandwidth demand. DWDM network system can not only carry SDH and other unlimited digital or analog signals, it can be used to provide a variety of services. Based on DWDM technology, the metropolitan area network can take full advantage of the bandwidth resource of optical fiber, greatly improve the system capacity as well as reduce the transmission cost. Compared with CWDM technology, DWDM platforms are capable of handling higher speed protocols, enabling transmission over 100G or 200G per wavelength and migration to 400G and beyond. For metropolitan area network MAN requiring high speed and great channel capacity across long distances, DWDM technology is the ideal solution.

Conclusion

To conclude, with the different 100G metro network scenarios, metro network connections can be varied based on different technologies. Today's metro network benefits a lot from DWDM-based platforms. Nevertheless, as technology develops and more devices are linked together, MAN networks will continue to grow in popularity and more efficient, high-capacity and low-cost platforms are expected to cater to customers’ growing demands.