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jclark / rpi-cm4-ptp-guide

Guide to using the hardware PTP support in the Raspberry Pi CM4
MIT License
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MOTU AVB switch as TC #15

Open kondou opened 1 year ago

kondou commented 1 year ago

It looks like two types of MOTU AVB switch and both are slightly different, but I'm not sure if there is any differences in its functionality.

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And I expected MOTU AVB switch behaves as TC and correction field in PTP data should have meaningful data, but seeing from the ethernet data via wireshark, correction field is always all zero. The result of tcpdump at slave shows all zero correlation data from GMC. All devices are connected to MOTU AVB switch. I have both types MOTU AVB switch, and I cannot see any data other than zero in correlation field for both type. The firmware of the switch is the latest one.

Do i misunderstand what TC does, or am I missing something?

jclark commented 1 year ago

It would be great to be able to get this working. I don't know much about this...

I am guessing that the problem here is that it is specifically an AVB switch rather than a general-purpose IEEE1588 switch, and that this means it will only work when IEEE1588 is being used in an AVB-compliant way.

AVB includes the 802.1AS profile of IEEE1588, which is also called gPTP, plus a bunch of other stuff. I see there's a file /usr/share/doc/linuxptp/configs/gPTP.cfg, so I think the first thing to try is using that config.

kondou commented 1 year ago

Thank you very much for the comment.

At first, I tried to run ptp4l with -2 while the configuration file was not changed, but it looked like no PTP related ethernet data sent to the network. Then I tried to use gPTP.cfg as the configuration file without -2 option, but ptp4l didn't send anything related to PTP. I ran tcpdump at PTP slave which was prepared to monitor how PTP slave behaves to see if any PTP ethernet data can be received.

Seeing from the situation, MOTU AVB switch may not be suitable for the current environment. This means there is no TC in my network environment, and I may not expect sub micro precision from GMC. Then, I may need to connect PTP slave directly to GMC without L2 switch...

jclark commented 1 year ago

That's surprising. I have tried ptp4l before with the -2 option and it worked fine (I was able to synchronize two CM4s).

kondou commented 1 year ago

Hmm, I have no idea why it doesn't work...

Honestly speaking, the reason why I need to have GMC is to use Dante connecting over WAN. Dante looks like expecting IP based PTP, not L2. In that sense, my decision to use MOTU AVB was incorrect (sigh...). I didn't consider so much when I tried to collect PTP enabled cheap switch. I simply referred to 'CM4 is missing IEEE1588-2008 support through BCM54210PE' when I decided to buy MOTU AVB without deep thought. I had already bought them before you announced rpi-cm4-ptp-guide..

Now, I think I need to have IES3110-8TF-R for my situation, and I see you've already been using IES3110-8TF without any issue. It'd be much helpful for me to let me know if I need to be careful to use this switch.

jclark commented 1 year ago

Looks like AVB also needs some VLANs and traffic control stuff. See https://tsn.readthedocs.io/avb.html#system-setup

But, as you say, if Dante is expecting UDP transport rather than L2, then I guess it's going to be difficult to make it work.

I just got an IES3110-8TF-R as well, but I haven't set it up yet. There's some updated FW here: https://www.fs.com/sg/products_support/search.html?id=148180 (which the IES3110-8TF doesn't yet have). the The CLI manual has a bunch of new PTP stuff. I think it's likely the best option.

kondou commented 1 year ago

Thank you very much for the information. Now, I give up MOTU AVB for my usage.

I've just ordered IES3110-8TF-R, which expects be delivered middle of June. Until I receive them, I try to be more familiar to PTP operation and its behavior.

p.s. For GNSS, I found how to enable QZSS a few days ago. I did survey several times changing where the antenna is located in the veranda, but it still didn't provide good result. I decreased the number of GPS to be used to avoid SVs which looked like observed via reflected radio wave via some of tall buildings around my house, and did survey again for short period. This provided much better result than what I've done many times. After survey, it started fixed (time) mode, and I decreased more of GPS so that QZSS would be referred much more. This may be tricky, but I'm going to see how it will look like.

JN19aban commented 1 year ago

If you want to use Dante / AES67 (udp transport) try to find a refurbished Cisco SG350 / CBS 350 they are cheap enough and have tons of configuration, but there are not PTP aware.

kondou commented 1 year ago

Thank you very much for the information.

I used to use SG300, not 350, for daily work, it's too noisy (fan noise) for private use. Even for the used one, it looks much expensive in Japan than what James suggested (feisu.com aka fs.com).

JN19aban commented 1 year ago

The 10 port versions have no fan as the biggest models but the fs are nice too.