-----Original Message----- From: Miroslav Lichvar [mailto:mlich...@redhat.com] Sent: 27 April 2021 21:54 To: Ramana Reddy Cc: linuxptp-devel@lists.sourceforge.net; Amar Subramanyam; Richard Cochran <richardcoch...@gmail.com> (richardcoch...@gmail.com) Subject: Re: [Linuxptp-devel] [PATCH] To support Ordinary Clock-Subordinate/Slave just a bunch of devices(jbod) feature.
CAUTION: This email originated from outside of Altiostar. Do not click on links or open attachments unless you recognize the sender and you are sure the content is safe. You will never be asked to reset your Altiostar password via email. On Tue, Apr 27, 2021 at 03:59:05PM +0000, Ramana Reddy wrote: > <Ramana> As I said, running independent clients defeats the purpose of BMC > algorithm and breaks the ITU-T G.8275.2 > Spec compliance. The BMC algorithm should be run locally on all ports of > every ordinary and boundary clock in a domain. Since it > runs continuously, it continually readapts to changes in the network or the > clocks. Pls check section 9.3 in IEEE1588-2008 > Spec for details on BMC algorithm. Also refer to Section 6.7 of A-BMCA > requirements of ITU-T G.8275.2 spec. Can you please refer to the exact page and paragraph which prevents multiple ptp4l instances to be running on a computer which has multiple clocks? Ramana> Can you please refer to IEEE1588-2008 spec section 9.3 Best Master Clock Algorithm and specifically it refers to below note in page # 84 : "The BMC algorithm is run locally on all ports of every ordinary and boundary clock in a domain. Since it runs continuously, it continually readapts to changes in the network or the clocks" PTP is specified from a clock point of view. If you have multiple clocks, you need multiple PTP instances, or you can pretend it's a single clock with the jbod option. In either case, your requirement "BMC algorithm should be run locally on all ports of every ordinary and boundary clock in a domain" is satisfied. > I tried --boundary_clock_jbod=1 --clientOnly=1 with two interfaces and > it seems to be switching them between the LISTENING and > UNCALIBRATED/SLAVE states as expected. > <Ramana> This I believe was explained in detailed on what are the existing > issues, design choices we have, > Motivation for the new changes. Pls refer attached mail from Amar. The only relevant part from that mail I found is this: > b. As the other PTP redundant ports part of bundle are in LISTENING > state, BMCA will not be able to select best master when there is best clock > carried in the other ports (other than the port which is already locked). > Please refer to IEEE1588 section 9.2.4 where they mention the definition of > LISTENING and PASSIVE state interpretations. Please explain what exactly prevents the selection. I didn't see it in my test. Ramana> I see there is some disconnect in understanding the existing issues. To ease the things, we tried to came up with Document listing all the existing issues with boundary_clock_job and ClientOnly config. We tried to be as much clear As possible. If you have any questions or need any clarifications, we could do a quick 30mins call tomorrow and help you clarify. Attached the document. Hope it helps. -- Miroslav Lichvar
issues_with_ptp4l_boundary_clock_client_only_mode_with_multiple_ports.docx
Description: issues_with_ptp4l_boundary_clock_client_only_mode_with_multiple_ports.docx
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