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Question 13/15

Question 13/15 - Network synchronization and time distribution performance
(Continuation of Q13/15 and Q15/15)
Motivation
Network synchronization performance specifications are essential for successful operation and integration of digital transmission networks and associated switching and signalling systems and mobile networks. Network timing performance studies are needed to determine the feasibility and most effective means of implementing a time reference distribution service.
This Question has already studied network synchronization issues related to PDH and SDH during Study Periods from 1988 until 2000, and to OTN during the 2001-2004 and 2008-2012 Study Periods. This question has also started studying the network synchronization issues related to packet networks with focus on mobile network needs from 2004 until 2012.
Continuing effort needs to be put into the study of synchronization issues in packet based networks.
New transmission technologies, services and facilities are regularly being introduced. Inter-operator links need to be efficiently installed, commissioned, brought into service and maintained. Test and measurement instrumentation is required for the installation, commissioning, bringing into service and maintenance of telecommunications equipment and networks. The measurement of the same parameter made with different measuring instruments should give reliable, repeatable and comparable results. Test equipment specification needs continuous review to take account of technology changes and improvements of jitter and wander measurement.
The following major Recommendations, in force at the time of approval of his Question, fall under its responsibility:
TDM: G.781, G.810, G.811, G.812, G.813, G.822, G.823, G.824, G.825 and G.8251
Packet networks: G.8260, G.8261, G.8262, G.8264, G.8265, G.8265.1, G.8261.1, G.8263 and G.8271
Test equipments:  O.172, O.173, O.182 and O.174
Question
Study items to be considered include, but are not limited to:
  • What are the requirements for jitter and wander for the future 100Gbit/s interface (HSSG related)?
  • What is the network functionality required to provide real-time distribution of absolute time-of-day reference services and/or phase synchronization? What network capabilities are required to support the performance levels necessary to satisfy a selected set of time-of-day and/or phase synchronization user applications?
  • How can network synchronization performance be enhanced through the use of synchronization status messages or other techniques?
  • What network synchronization characteristics, for both normal and degraded mode, should be recommended for services carried over packet networks? What is the dependence on synchronization of performance of various methods of service clock recovery with respect to service requirements (e.g., jitter, wander and slips, etc.)?
  • What network synchronization characteristics should be recommended for services carried over packet based networks?
  • What jitter and wander requirements are needed for wireless network applications (e.g., radio relay, satellite)?
  • What synchronization requirements are related to supporting the operation of the mobile network applications (e.g., LTE)?
  • What jitter and wander requirements are needed for access networks (e.g. DSL, PON)?
  • What jitter and wander specification requirements are needed in the evolution of OTN?
  • Synchronization aspects (frequency, phase and time) of packet networks, e.g. Ethernet, MPLS, IP networks.
  • Synchronization aspects related to supporting mobile network operations.
  • Synchronization aspects with regard to transport via satellite networks.
What manual and automatic test and measurement instrumentation and techniques to assess transmission performance need to be specified by ITU-T and what should be the specifications?
The following are examples of instrumentation and techniques which may be studied:
  • measurement and evaluation of error performance parameters and objectives;
  • test instrumentation and techniques associated with various technologies (e.g. PON, OTN PNT, Submarine systems and beyond 100G);
  • test instrumentation and techniques associated with Layer 1 Transmission technologies for metallic and optical media like 1G access, beyond 100G
  • jitter and wander test instrumentation and techniques associated with various technologies (e.g. , PON, OTN,PNT and beyond 100G);
  • test instrumentation and techniques associated with Optical Phase modulations (e.g. ODB,  DQPSK and DP-QPSK) ;
  • keeping O-Series Recommendations up to date.
Tasks
Tasks include, but are not limited to:
  • Continue development of recommendations related to the transport of frequency through packet networks, G.8260, G.8261, G.8261.1, G.8262, G.8263, G.8264 (and G.8265).
  • Continue development of recommendations related to the transport of phase and time through packet networks, G.8260, G.8271, G.8271.1, G.8272, G.8273, G.8273.1, G.8273.2, G.8273.3, G.8275, G.8275.1, G.8275.2 and others in the same series as necessary.
  • Revisions and enhancements to Recommendation G.8251.
  • Continue work on the transport of clients through OTN e.g. PTP, etc
  • Consider need for new Recommendation on jitter and wander instrumentation for packet-based networks (O-series), e.g. O.175. 
  • Consider need for new Recommendation on physical layer test instrumentation associated with Optical Phase modulations (ODB, DQPSK and DP-QPSK).
Relationships
Recommendations:
  • Q.551,  G.783, G.798, Y.1731, Y.17tom
  • G.81X series, G.825, G.783, G.8251, G.826X, G.827X series, GR 253
Questions:
  • Q2/15, Q3/15, Q4/15, Q6/15, Q8/15, Q9/15, Q10/15 and Q11/15
Study Groups:
  • ITU-T SG2 on telecommunication management
  • ITU-T SG13 on MPLS, OAM,  IP and NGN requirements
  • ITU-T SG9
  • ITU-R SG4 on satellites
  • ITU-R SG6 on broadcasting
  • ITU-R SG8 on mobile
  • ITU-R SG9 on radio relay
Standardization bodies, forums and consortia:
  • ATISCOAST on synchronization
  • IETF PWE3 on circuit over packet
  • IETF TICTOC
  • IETF NTP
  • MEF on circuit emulation over Ethernet and measurement delay
  • MEF mobile backhaul
  • IEEE 1588
  • IEEE 802.3
  • IEEE 802.1AS
  • IEEE 802.16 (Wireless MAN)
  • IEEE 3GPP
  • Broadband Forum
  • IEC TC86
  • Optical Interworking Forum (OIF)