1. Related work in other SDOs
Silvana Rodrigues
System Architect
Phone:

2. Standards Organizations
Multiple standards bodies are involved with Synchronisation of the Packet Network
International Telecommunication Union (ITU-T)
Defining synchronization requirements for Packet Networks
Institute of Electrical and Electronic Engineer – IEEE1588TM
Defining the Protocol to be used to carry Synchronisation over the Packet Network
IEEE802.1AS – Audio/Video Bridging Task Group
Timing and Synchronization for Time-Sensitive Applications in Bridged Local Area Networks
ATIS - Optical Transport and Synchronization Committee – OPTXS-SYNC
Defining a technical report “Synchronization of Packet Networks”

3. ITU-T – Study Group 15, Working Part 3, Question 13 – Synchronization experts group
October 2003
Proposal for investigating precision timing synchronization requirements & characteristics over asynchronous packet Networks were presented
April 2004 – Start the work on G.pactiming
February 2006
G.8261 (former G.pactiming) was consented
February 2006 – Question 13 decided to:
Continue to work on G.8261
Start the work on G.paclock
Start the work on G.pacmod
Rapporteur – Jean-Loup Ferrant from Alcatel

4. ITU, Study Group 15, Question 13 cont’d
ITU-T G.8261
Recommendation published in May 2006 available
Defines timing and synchronization elements of packet networks
Specifies the minimum equipment tolerance to jitter and wander at the boundary of the packet networks at TDM interfaces
Outlines the minimum requirements for the synchronization function of network elements
Editor: Stefano Ruffini from Ericsson
ITU-T G.pacmod
Under development
Defines various aspects related to timing distribution in packet networks and to its modeling.
Includes clock distribution (network and equipment), network equipment modeling and SSM usage
Editor: Michael Mayer from Nortel

5. ITU, Study Group 15, Question 13 cont’d
ITU-T G.paclock
Under development
Outlines minimum requirements for timing devices used in synchronizing network equipment that operates in the IWF and to other Network Elements as defined in G.8261
Supports clock distribution based on plesiochronous and network synchronous method (e.g. Synchronous Ethernet) and packet-based methods (e.g. Adaptive and Differential Clock Recovery)
Defines clock (PLL) performance characteristics such as wander, jitter, phase transients, clock bandwidth, frequency accuracy, holdover, etc…
Synchronous Ethernet clocks will be similar to G.813 (Timing characteristics of SDH equipment slave clocks – SEC) performance characteristics
Editor: Silvana Rodrigues from Zarlink

6. IEEE-1588
IEEE-1588 – Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems
Defines a Precision Time Protocol (PTP) designed to synchronize real-time clocks in a distributed system
Intended for Local Area Networks using multicast communications (including Ethernet)
IEEE-1588 designed to work within a building or factory
Intended typically for industrial automation and test and measurement systems (e.g. synchronized printing presses)
Targeted accuracy of microsecond to sub-microsecond
Approved in September 2002 and published November 2002
Available from the IEEE-1588 web site

7. IEEE-1588 – Version 2
The PAR (Project Authorization Request) was approved in March 2005
P1588 – Precise Networked Clock Synchronization Working Group was formed
Resolution of known errors
Conformance enhancements
Enhancements to address new applications (including telecom)
P1588 meets twice a week via conference calls
Chairman – John Eidson from Agilent
Secretary – Silvana Rodrigues from Zarlink
Editor – John MacKay from Progeny

8. IEEE-1588 – Version 2 cont’d
Version 2 of the standard includes key features for Telecom
Short Frame
Unicast
Fault Tolerant Clocks
Allows different methods for Master clock selection
The technical work is complete
No technical features will be introduced or deleted in the standard
Correct errors and ambiguities of technical facts
Correct editorial mistakes and English
Consider inputs from NIST for the security informative appendix
Letter ballot in April/May 2007

9. Profiles in Version 2
Profile is a set of required options, prohibited options, and the ranges and defaults of configurable attributes
“An IEEE-1588 profile may be developed by external organizations including:
a)  A recognized standards organization with jurisdiction over the industry, e.g. IEC, IEEE, IETF, ANSI, ITU, or;
b)  An industry trade association or other similar organization recognized within the industry as having standards authority for the industry;
c)   Other organizations as appropriate.”
The purpose of an IEEE 1588 profile is to allow organizations to specify specific selections of attribute values and optional features of IEEE 1588 that when using the same transport protocol will inter-work and achieve a performance that meets the requirements of a particular application.

10. IEEE 802.1AS
Home entertainment applications for voice, video, interactive applications and musical equipment
Trend is to use Ethernet to connect home entertainment equipment
For example, playing different audio tracks in each room, or playing same track in multiple room
Network model of 7 Switches
Synchronization accuracy
1us maximum wander from the grand-master station
Status
PAR approved May 25, 2006
Draft 0.6 available at
Editor: Geoff Garner from Samsung
AVB stands for Audio Video Bridging
1st bullet -> Residential Ethernet can be considered the backbone for home. There are also non-residential applications like Professional Audio/Video studios. All these applications need precise synchronization
2nd bullet:
Sometimes, the user wants one digital audio receiver to be
the “master” and control what songs are played in other
rooms through “slave” receivers
– A single song in the whole house
– A single song in selected rooms; e.g. living room, dining
room, and study, but not bedroom
• Simultaneous audio playing in multiple rooms requires
synchronization and phase control of audio within the
limits of human hearing to prevent “reverberation”
throughout the house

11. ATIS – OPTXS OPTXS-SYNC (formerly T1X1.3) United States input to ITU-T
Working on a technical report “Synchronization of Packet Networks”
addresses synchronization issues in packet networks
The technical report is going through the letter ballot process
United States input to ITU-T
US position
Sector member contributions
Next meeting
May 2007

12. Thank you!