Committed to connecting the world


Question 3/15

Question 3/15 - General characteristics of transport networks
(Continuation of Question 3/15)
The diffusion of the Internet, smartphones/mobile phones, and all the services that utilize networks―such as video distribution services have exceeded expectations for communication network services and continue to grow.  Those emerging and rapidly extending new services have been bringing drastic changes of transport networks. Moreover they require further innovation of transport networks and technologies to mainly energy and reduce costs of networks without significantly losing current operational experiences. It is also important that the transport networks are capable of improving operational capabilities, expanding service opportunities, and optimizing transport of IP, Etherent and other data traffics. These circumstances are forcing to bring in other technologies such as packet as well as new technologies such as OTN extension for an ultrahigh-speed ultrahigh-capacity transport network, all optical network, an converged transport network and packet-based time/timing distribution function and so on.
This situation led us to recognise that without strong coordination efforts there is the danger of duplication of work as well as the development of incompatible and non-interoperable standards. It also mandates us to:
  • study the appropriate core Questions (Question 3, 6, 7, 9, 10, 11, 12, 13, and 14/15),
  • define and maintain overall (standards) framework, in collaboration with other SGs and SDOs,
  • coordinate, assign and prioritise the studies done by the Study Groups (recognising their mandates) to ensure the development of consistent, complete and timely Recommendations,
SG15 is continuing studies under various Questions on the following aspects of optical transport networks, leading to several series of published and planned Recommendations. These Recommendations include aspects such as:
  • architecture;
  • equipment functional characteristics;
  • protection switching (linear, ring and shared-mesh)
  • operation, maintenance and administration(OAM);
  • structure and mapping aspects;
  • network synchronization and time/timing distribution functions;
  • management aspects;
  • control aspects (signalling, routing, discovery and restoration)
  • test and measurement functions;
  • physical layer characteristics physical media functions;
Standardization topics to be coordinated include:
  • OTN networks
  • Packet-based transport networks (Ethernet and MPLS-TP)
  • ASON (Automatically Switched Optical Network)
  • Maintenance of established standards such as SDH technologies
A coordination and communication activity among the involved Questions is fundamental in order to facilitate the most efficient completion of the work. This activity includes the identification of missing work areas and those that are overlapping, or potentially so, between multiple Questions or other standards groups. In case of a new work area, clarification of general requirements and framework by this Question would facilitate the work on specific aspects by relevant Questions. It includes encouraging the relevant work items in the most appropriate Questions, helping to define a suitable time schedule, and monitoring its development in a consistent way.
In addition, some general aspects such as terminology, reliability and availability, need to be captured.
A communications, publicity, and promotion activity is also important to support the adoption of ITU-T Recommendations throughout the industry. External communications activities should aid in the consistency of Recommendations and other standards related to optical and packet-based transport technologies across the industry.
The following major Recommendations, in force at the time of approval of this Question, fall under its responsibility: G.871, G.780/Y.1351, G.870/Y.1352, G.8081/Y.1353, G.8001/Y.1354, G.8101/Y.1355.
What characteristics of optical and packet-based transport networks still need to be fully developed in the various network environments (e.g. metropolitan, backbone, etc.), in what Study Question and within what time schedule?
What aspects of optical and packet-based transport networks, related to optical and packet transport of OTN, Ethernet, MPLS(-TP) and so on, need to be assigned to what Study Question for timely development?
What enhancements to OTNT SWP or what new Recommendation(s) or mechanisms are necessary to capture, within this framework, new or evolving aspects of optical transport networks, their general terminology, and reliability/availability characteristics?
What form of communication or publicity is prudent to enhance the use of and alignment with ITU-T standards in the area of optical and packet-based transport networks and technologies?
What are the general requirements for future optical and packet-based transport technologies and with what framework should each aspect of these technologies be developed?
What coordination is needed to provide energy savings directly or indirectly in Information and Communication Technology (ICTs) or in other industries?
Study items to be considered include, but are not limited to:
Coordination of work in the following areas:
  • Transport network protection/restoration  (Q9/15)
  • Interfaces, Interworking, OAM and Equipment specifications for Packet based Transport Networks  (Q10/15)
  • Signal structures, interfaces, equipment functions, and interworking for transport networks (Q11/15)
  • Transport network architectures   (Q12/15)
  • Network synchronization and time distribution performance (Q13/15)
  • Management and control of transport systems and equipment (Q14/15)
  • OTN physical layer characteristics (Q5, Q6 and Q7/15)
  • Optical systems for fibre access networks (Q2/15)
Tasks include, but are not limited to:
  • Develop, maintain, and regularly distribute a baseline overview/work plan that documents the work and time schedules of all major new optical transport network activities (OTNT SWP)
  • Prepare possible new Recommendation(s) to address the tasks above, and other items that may be identified (e.g. a terminology Recommendation), as required
  • Harmonize and align related terminology definitions across Recommendations, striving for a single normative definition for each term
  • Maintain terminology Recommendations G.780/Y.1351, G.870/Y.1352, G.8081/Y.1353, & G.8001/Y.1354,G.8101/Y.1355 in a timely manner by basically revising them to correct, add or delete corresponding terms and definitions in source Recommendations or other References.
  • Check if there are any duplicated terms and definitions at least within each technology and, if a duplication is identified, coordinate the issue to avoid the duplication as much as possible.
  • Develop Recommendations on general requirements and framework for optical and packet-based technologies. (Revise Recommendation G.871; as appropriate)
  • Publicize results of ITU-T related to optical and packet-based transport networks and technologies in the form of press releases, brochures, etc. when appropriate.
  • Coordinate any work during SG15 meeting to facilitate discussion among questions, including operators’ meeting, vendors’ meeting, off-line session and so on.
NOTE: An up-to-date status of work under this Question is contained in the SG15
  • Generic transport characteristics, OTN, Ethernet, MPLS-TP, SDH, ASON
  • Q2/15, Q6/15, Q7/15, Q9/15, Q10/15, Q11/15, Q12/15, Q13/15, Q14/15, Q9/12 and Q17/12.
Study Groups:
  • ITU-T SG13 on IP and NGN requirements
  • ITU-T SG12 on performance aspects
  • ITU-T SG2 on management aspects
Standardization bodies, forums and consortia:
  • IETF on IP-related networks and protocols related to ASON, OTN, MPLS(-TP) and AON
  • IEEE on Ethernet
  • MEF on Ethernet
  • OIF on optical networking
  • ATIS,
  • TIA
  • IEC