Sustainable, cost-efficient 100G connectivity for metro network

– which way should you go?

On the look-out for sustainable, cost-efficient 100G connectivity for your metro network?

Service providers, operators and wholesale carriers connecting business subscribers to their metro networks face increased demand for more bandwidth. An accelerating interest in cloud services, enhanced security through data-replication and, not least, growing media consumption drives the need for 100G connectivity in the metro environment.

Use the core network or create a separate metro network

In the metro area, service providers and operators serve the market from different data centers – spread out over a metropolitan area and interconnected by high-speed fiber optical links. While some data centers are seen as “main sites” and given nation-wide connectivity via the operator’s core DWDM network, other data centers primarily serve as connection points for enterprises, content providers and for capacity wholesale.

To serve metro area customers with high-speed links, service providers are faced with two alternatives. The first is to increase capacity by allowing metro traffic between data centers and direct to end users to run over existing core networks. A second option is to off-load the core network by creating a separate network layer for the metropolitan area – a metro network layer. While the first alternative might seem like an attractive option to avoid adding more complexity than necessary, connecting data centers in the metropolitan area or even connecting enterprise customers directly to the core network risks eating up far too much capacity in the core network. This is the main reason why most service providers today opt for creating a dedicated metro network.

Creating a cost-efficient, high-performance metro network

So, what are the needs for establishing a metro network which offers high-capacity links for short to medium distances? Service provider and operator core networks are typically created using large-scale, chassis-based, telco solutions, which need heavy, large-scale equipment and the skills of dedicated telecom engineers. The requirements for metro network deployment are often quite different.

Four factors typically come into consideration:

1. Optimized for shorter distances – While core networks are designed to span long distances across countries or regions, most metro networks cover distances around the 10 to 80 km range. Therefore, the focus is on solutions optimized for short to mid-range distances rather than regional access.

2. Higher expectations on cost-efficiency – Since business users are often spread across the city, the cost of the transport solution becomes an important decision factor when addressing multiple businesses across the metropolitan area.

3. Simplicity expected – For lower band-width metro networks, service providers have gotten used to relying on cost-efficient, easy-to-use, embedded WDM technologies. When scaling up to 100G, operators wonder if they will be forced to abandon the ease-of-use they have come to appreciate in favor of high-scale, chassis-based solutions for their metro network. The kind of solutions that require increased space, power and the integration, configuration and maintenance skills of experienced telecom engineers.

4. Sustainable solutions – A fourth, significant factor is the expectation to find a high-speed solution that is also sustainable in terms of not draining company resources when it comes to space and power consumption.

Open line systems for tomorrow’s metro network solutions


To conclude, service providers need a new approach for building modern metro network solutions supporting 100G traffic to cater for their business customers’ growing demands. The path to creating these next generation metro networks begins with using up-to-date disaggregated open line technology.

PAM4 transceivers, which come in a well-known QSFP28 format and are easily embedded in data center switches and routers, have become an attractive starting point for creating efficient 100G DWDM networking solutions. If existing switches do not support the use of embedded DWDM optics or when a 100G demarcation point toward the business customer is needed, an external transponder can easily be added to the solution. This way it is possible to create sustainable, low-cost, easy-to-use and yet highly efficient, high-capacity networks for short to medium distances in the metropolitan area.