Optical transport networks and bandwidth demand

Optical Transport Networks let operators reduce total cost of ownership while meeting increasing demand for bandwidth.

Listen to the podcast to learn more.

The continued demand for increased bandwidth has forced telecom operators to look for a transport solution that minimizes their total cost of ownership. Optical Transport Network (OTN) switching provides telcos with an efficient approach.

Consumers are driving this demand for more bandwidth and more services. They are increasingly opting for more bandwidth hungry applications and services supported by a new era of connected devices such as smart phones, smart TVs and tablets. Simultaneously, challenges for operators include:

  • Capacity growth in fixed residential networks driven by IP video
  • Backhaul pressure to support the rapid bandwidth uplift in mobile networks provided by LTE
  • Move to cloud based services by both business and residential customers

We see little slow-down in this growth. Research from Bell Labs suggests that from 2013 to 2017 we will see a 550% increase in bandwidth demand due to the shift to cloud and a 720% increase in bandwidth to support IP video across fixed and mobile networks. This will result in a 320% increase in the amount of traffic in the core network.

OTC needed to address bandwidth demand from Enterprise Cloud, mobile, business and residential usage

Figure 1: Demand for ever increasing bandwidth

Telecom operators are racing to meet consumer demand, and those that fall behind risk losing their high value clients. Furthermore, telecom operators must offer this increased bandwidth with little incremental revenue, so there is huge pressure to reduce the cost per bit for transport.

Optical Transport Network Forecast

Telecom operators are starting to realize that simply increasing the line rate is no longer sufficient to control the costs associated with increasing bandwidth demands. A recent survey by Infonetics predicted that by 2016, 86% of respondents plan to use OTN switching in the core of their networks[1]. In addition, Ovum forecasts that the growth of OTN will be proportionally linked with the growth of wavelengths that are 100G and beyond[2].

Key technologies for next-gen Optical transport network systems

Figure 2: Ovum’s technology pillars of next-gen transport systems

What is Optical Transport Network?

OTN is a defined in the ITU- Recommendation G.709 and is a set of optical network elements connected by optical fiber links, able to provide functionality of transport, multiplexing, switching, management, supervision and survivability of optical channels carrying client signals. OTN allows the photonic network to inherently support multiple protocols. Transport rates have been defined to maximize network utilization for a photonic network carrying many different service types.

Optical transport network universal network architecture

Figure 3: OTN Universal Network Architecture

What makes OTN so compelling for Telecom Operators?

Capacity Utilization
Optical Transport Network switching allows better network utilization by eliminating stranded bandwidth and maximizing wavelength utilization Network Convergence Using ODUk, Optical Transport Network supports multiple protocols and multiple bit rates, allowing operators to easily support new services on a single transport platform and to cost effectively and efficiently converge their legacy networks and services onto the same platform.

Optical Transport Networks  supports Multiple Protocols and multiple bit rates

Figure 4: OTN - Multiple Protocols, Multiple Bit Rates

Network Resilience
By using an Optical Transport Network as an overlay it is possible to add resiliency to legacy photonic networks where resiliency was previously not possible.

Service Utilization and Provisioning
Service requests for minimum or deterministic latency or specific protection schemes are more easily accommodated by an OTN enabled mesh network. OTN switching makes it easier for the telco to make service additions and changes.


With optical transport networking, telecom operators can move to a single converged network capable of cost-effectively and efficiently transporting new and legacy services in a way that maximizes network utilization.

Editor’s Note: The author would like to thank Kevin Drury for his contribution to this article.

Related Material

Read the Bell Labs: Metro Network Traffic Growth
Architecture Impact Study Visit the Agile Optical Networking website
Read the blog The Right Optics: Evolving the network to meet demand
The Urgent Need for Agility in Optical Networks ebook

To contact the author or request additional information, please send an email to


  1. [1] Infonetics Research: OTN, MPLS, and Control Plane Strategies: Global Service Provider Survey May 1, 2013
  2. [2] Ovum: 2014 Trends to Watch: Network Infrastructure Nov 1, 2013