Re: [sfc] Progression of use case documents in the SFC WG

["Jim Guichard (jguichar)" <[e-mail]>]

Hi Hongyu,

In our email to the list Thomas and I specifically said (with regards to draft-liu-sfc-use-cases):

"But that document includes text on three topics that would be covered in more detail elsewhere (broadband, mobile, and DC). While this document could contain pointers to the other documents, that leaves the document with very little standalone content -- raising the question of what should be done with it, or what content it could incorporate in order to be worthwhile as a standalone document.”

You will note that this is not an outright rejection of draft-liu-sfc-use-cases but rather specific questions on the validity of adopting the document given that our preference (and the majority of responses from the WG support this view) is to produce standalone documents for mobility and data center, and liaise with BBF for broadband. Therefore, what content is left in the more general document to justify adopting as a separate document? Further if adopted how as a WG can we avoid duplication of content across multiple documents?

From: "Hongyu Li (Julio)" <[e-mail]<mailto:[e-mail]>>
Date: Saturday, March 29, 2014 at 12:47 AM
To: Jim Guichard <[e-mail]<mailto:[e-mail]>>, "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>
Subject: RE: Progression of use case documents in the SFC WG

Objection to this proposal, which is contrary to major voice in previous email discussion as well as in London.

Draft-liu has its value at least in following aspects:


1.      It provides a general view of where SFC could be applied to. New comers don’t have to go through each standalone use case draft and read through tens of pages to understand scenarios.

2.      It is a container for those valuable use cases that don’t have to be a standalone draft to make it clear, even though listing all possible use cases is unnecessary. A good example is draft-krishnan-sfc-long-lived-flow-use-cases. It also a good place for reference to pertinent work in other SDOs, e.g. BBF, which can avoid duplicated work.

3.      It provides an abstraction of common features of all use case, see section 4 in latest revision draft-liu-sfc-use-cases<http://tools.ietf.org/id/draft-liu-sfc-use-cases-04.txt>. This is a good guidance for requirements and architecture derivation.

Hongyu

From: sfc [mailto:[e-mail]] On Behalf Of Jim Guichard (jguichar)
Sent: Thursday, March 27, 2014 1:54 AM
To: [e-mail]<mailto:[e-mail]>
Subject: [sfc] Progression of use case documents in the SFC WG

WG:

In a message back in January, we (the chairs) proposed that the SFC WG handle the topic of use case documents as follows:

1) Have the WG develop one use case document that documents a small number of representative use cases.  The document presented by Hongyu Li at the Vancouver BOF could serve for this purpose
(http://datatracker.ietf.org/doc/draft-liu-service-chaining-use-cases).

3) For additional use cases not covered in 1) above, allow for a small number of documents that are applicable to specific
environments (e.g.  mobility, data center, broadband, and so forth.) These documents would provide more detailed information and applicability of SFC to these specific environments, and would need to go beyond what is covered in the general use case document (1). Note that it is not the intention to have every potential use case documented.

Since then, and based on the presentations/discussion in London, it appears that we have a number of documents that warrant being developed as standalone documents. Specifically:

1) A use case document on mobility, e.g., http://datatracker.ietf.org/doc/draft-haeffner-sfc-use-case-mobility/

2) A use case document on Data Centers, e.g., http://datatracker.ietf.org/doc/draft-kumar-sfc-dc-use-cases/

3) Possibly a use case document on Broadband scenarios. However, use cases from a broadband perspective are being developed in the BBF (see the liaison statement at https://datatracker.ietf.org/liaison/1304/). We also have http://datatracker.ietf.org/doc/draft-meng-sfc-broadband-usecases/.  It does not seem appropriate to adopt a WG document on the topic of broadband (at least at this time) without clarifying the relationship between draft-meng-sfc-broadband-usecases and the BBF work. In addition, we would need to understand why two efforts — one in BBF and one in the IETF -- on the same topic would be appropriate. Hence, at the present time, we do not intend to adopt a WG document on broadband scenarios, and expect to receive primary guidance on this topic from the BBF.

That leaves: http://datatracker.ietf.org/doc/draft-liu-sfc-use-cases/, a more general document. But that document includes text on three topics that would be covered in more detail elsewhere (broadband, mobile, and DC). While this document could contain pointers to the other documents, that leaves the document with very little standalone content -- raising the question of what should be done with it, or what content it could incorporate in order to be worthwhile as a standalone document.

Thus, the chairs recommendation at this time is:

1) Call for WG adoption of draft-haeffner-sfc-use-case-mobility-00.txt and draft-kumar-sfc-dc-use-cases-00.txt as WG documents (target: informational).

2) Defer action on draft-liu-service-chaining-use-cases<http://datatracker.ietf.org/doc/draft-liu-service-chaining-use-cases>  and draft-meng-sfc-broadband-usecases<http://datatracker.ietf.org/doc/draft-meng-sfc-broadband-usecases/> per the above discussion.

Does this make sense?

Jim & Thomas