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Improvement for gPTP Gen 1 (IEEE 802.1 AS)

Improvement for gPTP Gen 1 (IEEE 802.1 AS). 08-01- 2013 IEEE 802.1 Plenary Meeting – Orlando Marcel Kießling, Siemens AG Franz-Josef Götz, Siemens AG. Structure of this Presentation. Recap of basic mechanisms Announce Frame Sync Frame Recap of the previous presented possible solutions

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Improvement for gPTP Gen 1 (IEEE 802.1 AS)

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  1. Improvement for gPTP Gen 1 (IEEE 802.1 AS) 08-01- 2013 IEEE 802.1 Plenary Meeting – Orlando Marcel Kießling, Siemens AG Franz-Josef Götz, Siemens AG

  2. Structure of this Presentation • Recap of basic mechanisms • Announce Frame • Sync Frame • Recap of the previous presented possible solutions • Network with “old” stored information • Proposed Solutions • Preferred Solution • Usage of the “syncReceiptTimeout” • Identification of the GM in the Sync

  3. Type of FramesSync- and Announce Frames • All gPTP frames are P2P frames • Announce frames • Elect best Grandmaster • Port Role (Slave / Master) • Sync frames • Time Sync • Path Delay frames • Measure Path/Link Delay • Request • Response • Response Follow Up

  4. Announce frame • Every device starts with periodically sending Announce Messages every announce interval • Announce Messages include the time-synchronization spanning tree vectors • Best Master Clock Algorithm (BMCA) uses these vectors to set up the loop-free Sync Tree (like BPDUs for the RSTP Tree) • Established Sync Tree

  5. Sync frame • Sync Frame is send more frequently than Announce Frames and includes information for synchronization • Follow the given sync tree established through announce frames • Loop prevention by using loop-free sync tree

  6. Problem with the 802.1 as Sync Tree • Stations with a Passive Port should not answer with old, previously stored information • Ring-Topology with stored GM Information's

  7. Structure of this Presentation • Recap of basic mechanisms • Announce Frame • Sync Frame • Recap of the previous presented possible solutions • Network with “old” stored information • Proposed Solutions • Preferred Solution • Usage of the “syncReceiptTimeout” • Identification of the GM in the Sync

  8. previous presented possible solutions • Optimized path trace TLV • Avoid long Announce Messages • Hop-Count • How to get a useful maximum Number • Deletion of stored information • What should cause the deletion • Using a special frame information • Like proprietary solutions • Using an timeout • Sync Messages are send out more often

  9. Structure of this Presentation • Recap of basic mechanisms • Announce Frame • Sync Frame • Recap of the previous presented possible solutions • Network with “old” stored information • Proposed Solutions • Preferred Solution • Usage of the “syncReceiptTimeout” • Identification of the GM in the Sync

  10. Usage of the “syncReceiptTimeout” • Definition: • Use the “syncReceiptTimeout” to • delete the stored information of the old GM on all ports (Passive Ports) • rerun the BMCA (without old information)

  11. Open Problem in Gen 1? – Identification of the GM • GM identification is not needed up to now because: • Only one GM exists • no Identification • Sync follow the loop free path • Port Roles block wrong frames

  12. Open Problem for Gen 2! – Identification of the GM • High Available Synchronization

  13. Thank you for your attention! Improvement for gPTP Gen 1 (IEEE 802.1 AS) Marcel Kießling Innovation Manager I IA SC IC TI Phone: +49(911)-895 3888 E-Mail: kiessling.marcel@siemens.com

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