Re: [Linuxptp-users] (no subject)

[Wolfgang W. <wol...@br...>]

Hi Delio,

> >> 2) Differences in the BMC algorithm
> >> 
> >> Is it possible to specify a different best master clock algorithm than that of the default PTP profile?
> > 
> > No, not yet.  I have some patches in the works for allowing different
> > BMC variants, because some profiles will require it.
> > 
> > However, the AS mode should work fine with the default BMC…
> 
> I can confirm AS mode works with the default BMC. As Richard says below the differences result in extra delays but peers eventually “converge”.

Ok, thanks for the clarification.

> >> 4) Path Trace TLV
> > @Delio, I see you allow announce without the TLV:
> > 
> >   https://github.com/audioscience/linuxptp/commit/0b6d8ca73332391af9bddc25177df254b066d669
> > 
> > Can you tell us why?
> 
> This is tricky because in some places 802.1AS-2011 seems to imply a TLV is mandatory but when you dig down into the implementation details you find that: in 10.3.13.2.1 (f) txAnnounce() appends the TLV *only if* it doesn’t exceed the transport’s MTU and in 10.3.10.2.1 (c) and (d) qualifyAnnounce() accepts an announce message without a TLV. So a TLV is present *if* it fits in the transport’s MTU but a compliant implementation has to accept an announce message without path trace TLV. 

I haven't studied the 802.1AS specification in detail yet, but your description matches my current understanding of how the path trace TLVs work.

regards, Wolfgang