Paul Littlewood is a principal engineer in Ciena’s CTO team, holds 7 patents in optical networking, and currently focuses on network architecture evolution, metro network design, and multilayer networking. Paul is also the co-author of the OTN Experts book (at right).

This is the fourth post in a series highlighting OTN technologies. Other posts in the series:


As OTN-based packet-optical networking deployments ramp up, it’s important for service providers and network operators to maximize the value from their investments. A critical consideration is to determine whether OTN switching can improve the efficiency of their networks.

OTN is broadly used by more than 80 percent of service providers and network operators across the globe to meet growing demands for scalable, wide area, long haul communications. However, many may not fully realize that the key capabilities OTN delivers can be used to reshape the economics of high-capacity networks.

For instance, by introducing OTN switches into transponder- or muxponder-based networks, operators and service providers can optimize bandwidth, streamline network efficiency, and improve wavelength fill. This approach also allows organizations to eliminate manual fiber connections used for capacity grooming at key locations across networks, to periodically reduce bandwidth fragmentation.

Adding OTN switching to an existing OTN transport network is a relatively smooth process that offers a quick return on investment. With proper equipment implementation, the simple addition of a couple of circuit packs to deployed network elements can upgrade them from transponders to switches.

OTN switching, when combined with a control plane automates operations, and enhances network resiliency through automatic reactions to network changes, including multiple simultaneous failures. It may also automate changes in network topology, or rearrange connectivity in response to, for example, an increase in latency across a network’s critical spans.

OTN switching also handles and executes daily operations (i.e., bandwidth increase requests, the setup of new or modifications to existing connections between end-points) in real time without requiring manual intervention. OTN switching can also be used to improve wavelength fill independent of use with a control plane.


5 key questions to determine if OTN switching can help your network

OTN switching can be retrospectively added to networks after organizations have weighed its cost versus benefit. Below are five crucial questions designed to help service providers and network operators determine if OTN switching will be cost effective in their networks:


1.)  By how much can my network efficiency be improved? In most large networks where line rates are greater than client rates (for example 100G lines and 10G clients), switches in the center of the network can deconstruct the muxing performed at the edge nodes, and repack with other traffic to fill the 100G lines more efficiently. This saves network capacity over standard OTN transport, which can only fill lines to the extent that traffic exists between edge node pairs. Ciena network studies have shown around 40% of deployed wavelengths can be saved using switching.

2.)  Will dynamic services be offered? An OTN switch is mandatory for service providers to automatically route switched services, especially those with multiple rates between differing end-points. For example, cloud and Software-Defined Networking (SDN) environments both require OTN switching to rearrange networks in order to meet dynamic service needs.

3.)  Does OTN switching align with the organization’s operational philosophy? While it may be acceptable to manage routing and efficiency with manual patch panels on smaller networks, it becomes far less effective as networks scale by the number of nodes and amount of traffic. Controlled from a central location, OTN switches reduce truck rolls and—with automation—reduce provisioning errors during traffic rearrangement. The switches also provide crucial data that details service and network connectivity, along with comprehensive performance measurements.

4.)  Would OTN switching accelerate service provisioning? For service providers working to beat the competition in service provisioning velocity, an OTN switch can be a valuable tool to quickly configure (and reconfigure) services across a network.

5.)  Is there a crucial service restoration requirement? To provide mesh restoration and improve disaster recovery, OTN switching and a distributed control plane are essential tools for re-routing traffic around failure points. Experience shows that this is a very cost efficient way to maintain network performance at better than five nines.


Service providers and network operations should absolutely examine OTN switching for use on OTNs that face ever-growing scalability demands, a need for optimized network utilization, enhanced network/service monitoring, and/or improved survivability.

Are you interested in examining OTN switching and its benefits for yourself? Download the free eBook, The Experts Guide to OTN, and start solving your business challenges today.