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Question 11/15

Question 11/15 - Signal structures, interfaces, equipment functions, and interworking for transport networks
(Continuation of Q11/15 and part of Q9/15)
The explosive growth of the Internet, optical networks, standardisation of 40 and 100Gbit/s Ethernet, anticipated standardisation of Ethernet rates greater than 100 Gbit/s, and other packet based traffic are the key drivers for the development of new transport network equipment and Network Node Interface (NNI) related standards. In addition, the development of the Optical Transport Network (OTN) provides the ability to dramatically increase the bandwidth, and thus traffic carrying capacity, of optical networks.  Furthermore, the advent of the ODUflex and the Hitless Adjustment of ODUflex (HAO) has enabled efficient data traffic transport over OTN in much the same way as the earlier development of Generic Framing Procedure (GFP), virtual concatenation and Link Capacity Adjustment Scheme (LCAS) did for SDH. This and other enhanced capabilities, as well as the need to support any new management capabilities, have resulted in a need for the revision of existing equipment Recommendations as well as the development of new Recommendations for transport equipment. Increased utilization of OTN technology for a wider set of applications has driven the demand for support of new client signals, including high speed Ethernet, Storage Area Network (SAN) interfaces (such as Fibre Channel and Enterprise Systems CONnection (ESCON) flows), as well as wireless network interfaces like Common Public Radio Interface (CPRI).   Further work is expected to enhance the OTN Recommendations to carry future Ethernet and other data client interfaces.
The area of responsibility under this Question includes:
  • Specification of transport signal structures, such as SDH, GFP, and OTN
  • Specification of adaptations of client signals into server transport layers
  • Specification of interface characteristics for the transport and supervision of client signals
  • Specification of all equipment functions, supervision  related to the OTN and SDH layer networks including equipment functions related to access networksSpecification of fundamental transmission parameters and determination of the effect of various transmission impairments. This includes transmission error and availability performance objectives and allocation methods for efficient design of digital networks and associated transmission equipment.
  • Investigation of power saving mechanisms for transport network equipment in the wider context of ICTs (Information and Communications Technologies).
  • Investigation and possible specification of OTN Services
The following major Recommendations, in force at the time of approval of this Question, fall under its responsibility: G.703, G.704, G.707/Y.1322, G.709/Y.1331, G.7041/Y.1303, G.7042/Y.1305, G.7043/Y.1343, G.7044/Y.1347, G.8040/Y.1340, X.85/Y.1321, X.86/Y.1323, G.705, G.781, G.783, G.798, G.798.1, G.806, G.821, G.826, G.827, G.828, G.829 and G.8201.
Study items to be considered include, but are not limited to:
  • What enhancements should be made to the existing NNI related Recommendations or what new Recommendations should be developed
    • for the Optical Transport Network (OTN) hierarchy to accommodate new Ethernet clients?
    • to reflect additional transport network applications (e.g. ASON) and interworking scenarios?
    • for networks optimized for transport of packet data, including packet over packet and circuit over packet adaptations and aspects related to connectionless layer networks?
  • What transport equipment functions must be specified to enable compatible transport equipment in inter-office and long distance networks, including evolution to the optical transport network?
  • What transmission error performance parameters and objectives need to be recommended?
  • What enhancements should be made to the existing equipment function Recommendations or what new Recommendations should be developed :
    • for the SDH and OTN (OTN equipment in this context relates to equipment functions and the assembly of optical components and sub-systems)?
    • to support the development of CBR transport over packet based networks?
    • in order to meet the needs of  the access network, the NGN and transport of Internet and other packet based traffic?  This includes examining the impact, if any, on synchronisation layer functions.
  • What should be specified for the definition of new transport networks (including NGN), while insuring transverse compatibility and interworking with previously specified technologies?
  • What enhancements to existing Recommendations are required to provide energy savings directly or indirectly in Information and Communication Technologies (ICTs) or in other industries? What enhancements to developing or new Recommendations are required to provide such energy savings?
  • What OTN services exist and how should they be specified?  What are the interfaces (UNI/ENNI) and transfer characteristics of OTN services?
Tasks include, but are not limited to:
  • Enhancement to relevant Recommendations for transport networks to increase network transport capacity and accommodate greater than100 Gbit/s Ethernet services
  • Maintain and update, as necessary, OTN equipment Recommendations G.798 and G.798.1
  • Maintain and update, as necessary, the error performance Recommendations G.821, G.826, G.827, G.828, G.829 and G.8201
  • Maintain and update, as necessary, PDH, SDH, OTN and LAPS Recommendations
  • Evolution of GFP, LCAS, and HAO related Recommendations
  • Further development of the OTN Interface Recommendation
  • Development of OTN service definitions
NOTE: An up-to-date status of work under this Question is contained in the SG15 Work Programme at:
  • G.784, G.825, G.7710, G.693, G.694, G.695, G.698, G.8080, G.8110, G.8251, G.8261, G.8262, G.8264, G.993.x, Y.2601 and Y.2611
  • G.783, G.798, G.806, G.872, G.957, G.959.1, G.8010, G.8021, G.8110.1 and G.8121.
  • Q3/15, Q4/15, Q6/15, Q9/15, Q10/15, Q12/15, Q13/15 and Q14/15.
Study Groups:
  • ITU-T SG2 on network maintenance
  • ITU-T SG12 on network performance
  • ITU-T SG13 responsible for NGN aspects
Standardization bodies, forums and consortia:
  • MEF on Ethernet services and Ethernet Equipment
  • IEEE 802.1, 802.3on Ethernet
  • IEEE 802.17 on Resilient Packet Rings
  • T11 on SAN flows transport
  • IETF working groups on MPLS and IP transport  packet/circuit over packet