improvement for gptp gen 1 (ieee 802.1 as)
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
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
IEEE 802.1 Plenary Session – OrlandoPage 2 2013-03-14
Structure of this Presentation
1. Recap of basic mechanisms
- Announce Frame
- Sync Frame
2. Recap of the previous presented possible solutions
- Network with “old” stored information
- Proposed Solutions
3. Preferred Solution
- Usage of the “syncReceiptTimeout”
- Identification of the GM in the Sync
IEEE 802.1 Plenary Session – OrlandoPage 3 2013-03-14
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
IEEE 802.1 Plenary Session – OrlandoPage 4 2013-03-14
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)
B0
B1 B3
B2
B4 GM
M MSS
MMS P
MS
M
S
P
MasterPort (RSTP Designated-Port)
SlavePort (RSTP-Root Port)
PassivePort (other States)
DisabledPortD
Time Aware System (Bridge /End-Station)
B5M SM
M
Established Sync Tree
IEEE 802.1 Plenary Session – OrlandoPage 5 2013-03-14
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
B4 GM1
B0
B1 B3
B2
B5
Sync Messages
IEEE 802.1 Plenary Session – OrlandoPage 6 2013-03-14
Problem with the 802.1 as Sync Tree
Stations with a Passive Port should not answer with old, previously stored informationRing-Topology with stored GM Information's
B0
B1 B3
B2
B4 GM
M MSS
MMS P
MS
GM + GM-failed
Old GM
GM
Stack-Time
31 20S P31 20 SP
31 20
Sharing of „wrong“ GM Information
Answer with stored Information
Wished Behaviournew Information should renew
the old stored information
Real behaviour stored information dominates
Deletion of the old stored information
IEEE 802.1 Plenary Session – OrlandoPage 7 2013-03-14
Structure of this Presentation
1. Recap of basic mechanisms
- Announce Frame
- Sync Frame
2. Recap of the previous presented possible solutions
- Network with “old” stored information
- Proposed Solutions
3. Preferred Solution
- Usage of the “syncReceiptTimeout”
- Identification of the GM in the Sync
IEEE 802.1 Plenary Session – OrlandoPage 8 2013-03-14
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
Industrial Ring
B0 B1
B48B2
GM
1
2
3
50
B3
B49
B4750 devices in the Ring
49
48
GM1
2 GM B0
16 Byte
4 Byte
Path SequenceTLV Type+ Length
N * 8 Byte
802.1 as Announce Frame
„Guard“-Timer to remind the deletion of the GM
S PSP
0 1 2 3
IEEE 802.1 Plenary Session – OrlandoPage 9 2013-03-14
Structure of this Presentation
1. Recap of basic mechanisms
- Announce Frame
- Sync Frame
2. Recap of the previous presented possible solutions
- Network with “old” stored information
- Proposed Solutions
3. Preferred Solution
- Usage of the “syncReceiptTimeout”
- Identification of the GM in the Sync
IEEE 802.1 Plenary Session – OrlandoPage 10 2013-03-14
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)
IEEE 802.1 Plenary Session – OrlandoPage 11 2013-03-14
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 B4 GM
Established Sync-Path
B0
B1 B3
B2
B5GM2
M
S
Sync Message
GM1
GM2
P
Sync Path Diode
B
IEEE 802.1 Plenary Session – OrlandoPage 12 2013-03-14
Open Problem for Gen 2! – Identification of the GM
High Available Synchronization
B4 GM
Established Sync-Path
B0
B1 B3
B2
B5
M
S
Sync Message
GM1
GM2
P
Sync Path Diode
B4
B0
B1 B3
B2
B5GM
P
Sync-Pathfor GM 1
Sync-Pathfor GM 2
Sync from GM1 or GM2 ?
B4 GM
Only OnlyB5GM
=
B4 GM1
B0
B1 B3
B2
B5GM2
B4 GM1
B5GM2
&
Marcel KießlingInnovation ManagerI IA SC IC TI
Phone: +49(911)-895 3888
E-Mail: [email protected]
Thank you for your attention!
Improvement for gPTP Gen 1 (IEEE 802.1 AS)