Double Migration of Packet Clocks

Transcription

1 Double Migration of Packet Clocks Kenneth Hann Principal Engineer Artwork:Tanja Hann November 1,

2 Packet Clocks... the first migration Land of Phase Data Com Republic Legacy Land

3 Packet Clocks... the first migration Land of Phase Data Com Republic Legacy Land

4 Packet Clocks... the first migration Land of Phase Data Com Republic Legacy Land

5 Agenda 1. From here Timely progress 3. Supporting PTP migration 4. To Phase (eventually) 5. Conclusions 1st Migration 2nd Migration 10/25/10 5

6 1. From here : mobile FDD Ethernet backhaul that last E1 November 1,

7 From Legacy Sync... to SyncE E1 Operator Network (TDM) N x E1 Ethernet Network RNC N x E1 all SyncE Network RNC SyncE flow

8 From Legacy Sync... to PTP E1 Operator Network (TDM) N x E1 Network (3rd party) RNC N x E1 PTP slave Network (3rd party) PTP master RNC PTP timing flow (G )

9 From Legacy Sync... to Hybrid networks E1 Operator Network (TDM) N x E1 Network (3rd party) RNC N x E1 PTP slave Network (3rd party) PTP master RNC SyncE PTP timing flow SyncE flow

10 2. Timely Progress Network limits G Packet Equipment Clock model G.8263 PEC knowledge base G.8260 November 1,

11 Output limits for a packet Clock (frequency / FDD applications) G Sneak Preview 50ppb 2us 18us MTIE 2us +16ppb 18us + 50ppb Or... MTIE 18 µs 9 µs 16ppb 18us + 16ppb Observation interval τ (s) 2G / 3G / LTE mobile requires 50ppb frequency stability 11

12 Factors impacting Packet clock performance : Local oscillator stability Accuracy of timestamps Sync rate PDV characteristics of the network PDV filtering in the packet clock 2011 Packet selection algorithm Number of synchronization flows in Ensemble Ensemble combining algorithm 2010 Adaptive clock recovery algorithm None Some of above being standardized

13 Model of a frequency PEC (G.8263) Master_1... Master_n Packet selection Ensemble 2 nd order PLL PEC output Noise Amplitude (us) November 1,

14 PEC output for worst case input Worst case Noise Amplitude 2 nd order PLL Output FFO November 1,

15 Max output FFO for all frequencies (ppb) Packet Equipment Clock model not just secret plans and clever tricks PEC Time constant guarentees a noise tolerance Time Constant (seconds) 100µs PDV Triangular noise 200µs PDV Triangular noise 500µs PDV Triangular noise 16ppb objective 5000s line November 1,

16 3. Supporting PTP migration (Frequency FDD) PDV metrics Clock output monitoring Live network deployments 10/25/10 16

17 Monitoring of the Synchronization network Mobile networks: need synchronization <50ppb May be >10,000 nodes Some must migrate to IEEE1588 PECs viewed with suspicion Are fairly new Telecom standards still evolving Performance partially dependent on network conditions Operators need to be conservative 17

18 Packet Metrics work in progress Available, but... Hard to interpret... Needs mapped to FFO /25/10 18

19 IEEE1588 Clock Monitoring True PEC output monitoring (Built-in wander meter) q PEC Phase comparitor q SD H Needs a reference, but... Fortunately legacy provides the reference (temporarily). TIE + MTIE > Mask Alarm q SD H q PEC... Node Clock 10/25/10 19

20 TIE measurement TIE measurements

21 MTIE measurements (up to 10 x 24h) 21

22 Which of my 10,000 nodes should I monitor? Filter for 1588 Mask Crossed alarms Change mask for senarios Why not monitor all 10,000? March 14, DRAFT 22

23 Network management Supports 1588 clock monitoring Select reference (for Migration use last E1 ). Configure MTIE mask and monitoring period Set Fall Back List priorities (determines node clock) E.g. Initially E1 then switch to PTP Automate configuration using tools; rules and macros March 14, DRAFT 23

24 Large scale evaluation of IEEE1588 performance (TDM to IEEE1588 migration) Work flow: 1. Configure clock monitoring (Node clock = E1) 2. Periodically during migration filter faults to show synchronization trouble spots launch clock monitoring on selected node optionally tighten MTIE mask for scenarios 3. Preference PTP over E1 (Node clock = PTP) (clock selection process does the switchover) 4. Decommission the last E1 from nodes Perhaps leave a few measurements points... March 14, DRAFT 24

25 4. Future Directions (phase synchronization TDD/LTE adv.) Phase requirements (new network) Telecoms boundary clock Network phase & service phase 10/25/10 25

26 Telecom Phase and frequency solutions are very different but same management (SSM) for both 10/25/10 26

27 Prepare for the phase migration RNC LTE-TDD and LTE-advanced Require phase synchronization 1us or better accuracy GPS extension using IEEE1588 GPS Network (Ethernet) GPS Standardization work ongoing Nodes T-BC Hardware Ready PPS Initially islands around 10/25/10 GPS27

28 Synchronization Topology Provisioned, uses SSM for ring protection L3 L2 PR T C L1 L3 SyncE Microwave links SyncE 10G SDH RNC Migration to support phase means Upgrading PRC to PRTC Upgrading EEC s to T-BC s Network timing flow Network phase flow Topology management is the same for phase 10/25/10 28

29 Phase sync needs 4 timestamps Delivery mechanisms differ... Master T1 T4 a) Slave T2 T3 T4 IEEE1588 Delay Request Mechanism T2 T3 b) T1 T4 ESMC timestamp mechanism (Phase Synchronous Ethernet) T2 c) T1 T3 T4 IEEE1588 Pdelay Request Mechanism (Sync message free for Service Phase ) November 1,

30 Service phase and Network Phase Service Phase(s) SGW SGW L3 IP Network Phase L2 Ethernet Network Frequency L1 SyncE Telecoms BC Service GW T-BC Telecoms BC Service GW E.g. When a carrier has several mobile customers... 10/25/10 30

31 5. Conclusions Everyone is leaving Legacy Land on... SyncE; PTP; Hybrid (or anything that floats) Packet Equipment clocks - ready for Ethernet prime-time PEC output monitoring gives a confidence boost Last service of the Last E1 Large-scale, live network, field monitoring is available Prepare for 2 nd migration Phase support needs new clocks (Nodes HW phase ready ) SSM and the sync hierarchy remain the same! 10/25/10 31

32 Thank you! Questions?

33 Enabling the mobile Internet November 1,

34 A PEC s got to know it s limitations PTSF 10/25/10 34