Committed to connecting the world


Question 12

​​Question 12/15 – Transport network architectures

(Update of Question 12/15 to include some of the work of Q9/15)

Transport network architecture Recommendations (G.800, G.805 and G.809) and technology specific network architecture Recommendations (G.803, G.872, G.8010, G.8110, G.8110.1 and I.326) have been established and are widely used. As operating experience is gained with employing current transport network technologies and new technologies evolve (e.g., variable size packets, high-speed transport networks), new Recommendations, or enhancements to existing Recommendations need to be developed, in close cooperation with the standardization activities on transport network systems and equipment. The operational aspects of networks, including the use of ASON or SDN for restoration, are becoming more important. The operational aspects of combined packet and circuit switched optical networks should be considered to ensure that they are addressed in a way that is architecturally sound and minimizes divergent approaches.
Software Defined Networking (SDN) is an architectural approach to managing transport network resources.  Its architecture needs to be understood in the context of the management control continuum that includes the Architecture of the Automatically Switched Optical Network (G.8080). Commonality and differences with existing architectures requires study as it is applied to various transport layers.  Requirements for enhanced control interfaces to and within the transport network, for example to support network slicing, need to be studied. Interfaces to configure and control programmable hardware are needed.  Interfaces that enable clients to request network services beyond basic connectivity are needed.

Network Functions Virtualisation (NFV) is an architectural approach in which some network functions are implemented as a programme on a generic compute platform. There are strong synergies between SDN and NFV especially in the goal of providing automated control. This drives the need for compatible enhanced control interfaces. This suggests the need for strong compatibility between the functional modelling currently used for the transport network and the functional model for NFV.

The continued evolution of transport networks and the services they support such as, the Internet, IMT-2020/5G, datacentre-based services, and higher definition video, have resulted in drastic changes in the demands placed on transport networks. Transport networks need to continuously evolve to meet these changing demands and provide a converged transport network. This rapidly evolving situation led us to recognise the need for a coordination and communication activity among the involved Questions (primarily Questions 2, 6, 7, 9, 10, 11, 12, 13, and 14/15) in order to avoid duplication of work and facilitate the most efficient completion of the work. Also, a standardization work plan for new optical transport network activities (the Optical Transport Networks and Technology Standardization Work Plan (OTNT SWP)) needs to be maintained. In addition, some general aspects such as terminology, need to be captured.

The following major Recommendations, in force at the time of approval of his Question, fall under its responsibility: G.800, G.803, G.805, G.809, G.872, G.7701, G.7702, G.8010/Y.1306, G.8080/Y.1304, G.8081/Y.1353, G.8110/Y.1370, G.8110.1/Y.1370.1 and I.326.

What new or modifications to existing Recommendations are required to:
Study items to be considered include, but are not limited to:
Tasks include, but are not limited to:
NOTE − An up-to-date status of work under this Question is contained in the SG15 Work Programme at:


Study Groups:
Standardization bodies, forums and consortia: