Re: [Linuxptp-devel] 802.1AS Time-Aware Bridge
On Mon, Mar 27, 2017 at 12:32:46PM +0200, Burkhard Ilsen wrote: > My use case is a bridged end-station, i.e. a time-aware bridge with an > application that needs to be synchronized. So we don't actually support TC or TAB. Those patches were only a rudimentary proof of concept. Did you see the TODO list? > The AS model of operation allows every time-aware system (including TAB) to > include a ClockSlave and provide an application interface to a ClockTarget. If you are talking about 802.1AS-2011 Clause 9, then I recommend just ignoring it. It is not one of the more brilliant examples of standards writing. In linuxptp, applications can find out everything they need to know via the management interface. In particular, the TIME_STATUS_NP TLV is designed for use with gPTP and the free_running option. > Syntonization is done by multiplying the residence time with the rate ratio, > no servo needed, right? No, syntonization means choosing a master and calculating the rate ratio. > So the servo should be free for synchronizing the ClockSlave but this > requires the offset. > Would this be possible with linuxptp? > Any advice is appreciated. You have two options: 1. Use TIME_STATUS_NP and implement the servo in the application. 2. Adjust the TC clock. Depending on your environment, this may be acceptable. Even though 802.1AS-2011 says not to, 1588 allows it. HTH, Richard -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot ___ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
Re: [Linuxptp-devel] 802.1AS Time-Aware Bridge
>> According to 802.1 AS all message timestamps shall be based on a free >> running clock (LocalClock) in order to minimize the errors resulting from a >> varying clock frequency. >> Also phase discontinuities in the pdelay_resp(fup) messages are avoided this >> way. >> So the SlaveClock controlled by the servo is different from the hardware >> clock taking the timestamps. >> An implementation would require to translate hardware timestamps into the >> SlaveClock epoch to compute the master offset correctly. >> >> I was not able to find this behavior implemented in linuxptp. Did I miss >> something, or was this already issued? >You are mistaken. The master offset is irrelevant for TC operation. >The TC is supposed to syntonize only. You are right, a plain TC does not need the offset. My use case is a bridged end-station, i.e. a time-aware bridge with an application that needs to be synchronized. The AS model of operation allows every time-aware system (including TAB) to include a ClockSlave and provide an application interface to a ClockTarget. Syntonization is done by multiplying the residence time with the rate ratio, no servo needed, right? So the servo should be free for synchronizing the ClockSlave but this requires the offset. Would this be possible with linuxptp? Any advice is appreciated. Regards, Burkhard Hilscher Gesellschaft für Systemautomation mbH | Rheinstrasse 15 | 65795 Hattersheim | Germany | www.hilscher.com Sitz der Gesellschaft / place of business: Hattersheim | Geschäftsführer / managing director: Dipl.-Ing. Hans-Jürgen Hilscher Handelsregister / commercial register: Frankfurt B 26873 | Ust. Idnr. / VAT No.: DE113852715 Registergericht / register court: Amtsgericht Frankfurt/Main Important Information: This e-mail message including its attachments contains confidential and legally protected information solely intended for the addressee. If you are not the intended addressee of this message, please contact the addresser immediately and delete this message including its attachments. The unauthorized dissemination, copying and change of this e-mail are strictly forbidden. The addresser shall not be liable for the content of such changed e-mails. Wichtiger Hinweis: Diese E-Mail einschließlich ihrer Anhänge enthält vertrauliche und rechtlich geschützte Informationen, die nur für den Adressaten bestimmt sind. Sollten Sie nicht der bezeichnete Adressat sein, so teilen Sie dies bitte dem Absender umgehend mit und löschen Sie diese Nachricht und ihre Anhänge. Die unbefugte Weitergabe, das Anfertigen von Kopien und jede Veränderung der E-Mail ist untersagt. Der Absender haftet nicht für Inhalte von veränderten E-Mails. Body.rtf Description: Binary data -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot___ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
Re: [Linuxptp-devel] 802.1AS Time-Aware Bridge
I’d like to use the JBOD mode with intel i210s. It seems like the “just use standard Linux interfaces” approach means it will work with just about any configuration! From: Chris Healy [mailto:cphe...@gmail.com] Sent: Thursday, September 15, 2016 2:21 PM To: Erik Hons <erik.h...@ni.com> Subject: Re: [Linuxptp-devel] 802.1AS Time-Aware Bridge Hi Erik, I was interested in getting this working in the past but have not had a chance to dedicate the energy. What type of HW configuration are you looking at making it work with? Regards, Chris On Thu, Sep 15, 2016 at 11:51 AM, Erik Hons <erik.h...@ni.com<mailto:erik.h...@ni.com>> wrote: Hey All, Sorry if this has come up before. I scanned the archive but didn’t see anything about this. Is there a technical or deliberate reason that ptp4l doesn’t support 802.1AS time-aware bridge? If not, would the project be open to that being contributed? -- ___ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net<mailto:Linuxptp-devel@lists.sourceforge.net> https://lists.sourceforge.net/lists/listinfo/linuxptp-devel -- ___ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
Re: [Linuxptp-devel] 802.1AS Time-Aware Bridge
I don't have a working version to post I'm afraid. But I'm considering making the effort. Sounds like it'd be well received! Can you share the TC concept you did? And the direction you need it to go? It wouldn't happen to be this would it: https://github.com/richardcochran/linuxptp-as/ -Original Message- From: Richard Cochran [mailto:richardcoch...@gmail.com] Sent: Thursday, September 15, 2016 3:55 PM To: Erik Hons <erik.h...@ni.com> Cc: linuxptp-devel@lists.sourceforge.net Subject: Re: [Linuxptp-devel] 802.1AS Time-Aware Bridge On Thu, Sep 15, 2016 at 06:51:35PM +, Erik Hons wrote: > Is there a technical or deliberate reason that ptp4l doesn't support > 802.1AS time-aware bridge? The only reason is that this feature would be a lot of work. > If not, would the project be open to that being contributed? (Wow, you have it already? Please post it ;) I already did a simple proof of concept for a P2P TC, and that is not too different from a TAB. I know the direction to go, but it will have to wait until I find some free time... So I do want to have TC/TAB in linuxptp for version 2.0. Thanks, Richard -- ___ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
Re: [Linuxptp-devel] 802.1AS Time-Aware Bridge
On Thu, Sep 15, 2016 at 06:51:35PM +, Erik Hons wrote: > Is there a technical or deliberate reason that ptp4l doesn't support > 802.1AS time-aware bridge? The only reason is that this feature would be a lot of work. > If not, would the project be open to that being contributed? (Wow, you have it already? Please post it ;) I already did a simple proof of concept for a P2P TC, and that is not too different from a TAB. I know the direction to go, but it will have to wait until I find some free time... So I do want to have TC/TAB in linuxptp for version 2.0. Thanks, Richard -- ___ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
