Re: [Rift] AD review https://datatracker.ietf.org/doc/draft-ietf-rift-rift/ (v-18) (review up to Section 4.3)

[James Guichard <[e-mail]>]

Okay makes sense and I can see your point of view – not a big deal.

Jim

From: Tony Przygienda <[e-mail]>
Sent: Friday, September 29, 2023 2:49 PM
To: Jordan Head <jhead=[e-mail]>
Cc: James Guichard <[e-mail]>; [e-mail]; [e-mail]
Subject: Re: [Rift] AD review https://datatracker.ietf.org/doc/draft-ietf-rift-rift/ (v-18) (review up to Section 4.3)

I just chime in on one bigger topic


Section 4.1.5:  Addressing the Fallen Leaves Problem

Jim> General comment: I think the document would be much easier to follow if sections 4.1.2 - 4.1.5 were moved into an appendix with a pointer to
that appendix in section 4.1.1 (for those readers interested in multiplane). For those readers not familiar with complex datacenter design it is
going to be very confusing to read and in some sense detracts from the specification which is the next section.

jhead>> I will concede that this topic quite dense, but that’s just the nature of multiplane fabrics. However, this is a protocol specification that at baseline is for those who plan to implement the protocol in its entirety. The Reader’s Digest section exists to help readers navigate the document depending upon their level and area of interest. For those that are interested in multiplane fabrics, moving the section to the appendix will not shield them from the complexity, but I do think it will make the document feel disjointed. For those who are not interested, be it an implementor or an operator, the Reader’s Digest will steer them around the topic.



I'm fully with Jordan here. Moving this section down will make lots of specification parts like e.g. negative disaggregation and necessity to flood northbound on horizontal links at ToF completely incomprehensible. Reader's digest already explains the structure if one wants to skip the multiplane while possibly being baffled by some things down later but e.g. the explanation of generic concept of representation of fabric and its variables (thanks Pascal here) and the resulting problems of falling leaves/inversion I hear good things about. Some large shops ended up telling their engineers to read those sections to normalize the language spoken about fabrics, even when not running rift or further pursuing its concepts in production

-- tony