Re: Gen-art LC review: draft-ietf-teas-te-express-path-03

[Robert Sparks <rjsparks@xxxxxxxxxxx>]

On 10/1/15 8:49 AM, Alia Atlas wrote:

Hi Robert,

Thanks for your review.

On Mon, Sep 28, 2015 at 3:29 PM, Robert Sparks <rjsparks@xxxxxxxxxxx> wrote:

I am the assigned Gen-ART reviewer for this draft. The General Area
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by the IESG for the IETF Chair.  Please treat these comments just
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Document: draft-ietf-teas-te-express-path-03
Reviewer: Robert Sparks
Review Date: 28 Sep 2015
IETF LC End Date: 30 Sep 2015
IESG Telechat date: 1 Oct 2015

Summary: Ready for publication as Informational, with nits

Nits/editorial comments:

This document is all about considerations. Specifically, it discusses what to consider if you were to build a path computation function that uses the kind of information you get from the TE metric extensions in RFC7471 and draft-ietf-isis-te-metric-extensions. It does not appear to be requirements for standardization work - rather, it is information for operators to use when building functions that don't necessarily need standardization.

However, it looks as if the document may have once contemplated actually specifying a path computation function, and has legacy text from that thought?

No - it was always about how one could use the information and isn't trying to standardize a particular function. 

 

The abstract says "This specification uses network performance data ... to perform such path selections." But this document doesn't perform such path selections (or specify how to do them).

Would you prefer

"This specification describes how a path computation function may use network performance data, such as is advertised via the OSPF and ISIS TE metric extensions (defined outside the scope of this document) to perform such path selections."

Yes, thanks!

 

Section 1.1 says "The following are the requirements that motivate this solution." But this draft doesn't actually specify a "solution". It discusses what to consider if you were to build a path computation function. Could this be framed as a set of goals to keep in mind while building your own such function?

Would you be ok with changing it to ".. that motivate this document?"

They were used to drive the document contents (that's not obvious) and not to inform what an implementation should achieve?

Perhaps the sentence could be replaced with

"As these considerations were assembled, care was taken to discuss points relevant to an implementation's ability to:"

?

 

The third paragraph of section 1.2 could use clarification. I suspect the word "even" in the 4th sentence should be removed, and the judgement in "There may be legitimate use" is out of place. Consider rewriting the paragraph using simpler sentences.

I've removed the word "even" and changed the last sentence about "There may be legitimate use..." to be

"However, there may be uses of a..."

Section 2.3 appears to be considerations specifically for interpreting the anomalous bit in one specific extension? If so, the introduction to the section should call that out. If not, the section's structure needs improvement. The section also calls out two questions, but only discusses one of them explicitly.

 In Sec 2.3.1, the anomalous bit behavior is described for latency, loss, and jitter.  On double-checking, I see that the Anomalous Bit was removed for jitter in RFC7471 and draft-ietf-isis-te-metric-extensions.   I've removed the last sentence in the second paragraph of 2.3.1 that discussed how to handle that case.

Sec 2.3.2 discusses the second question and how to handle it in detail.  

Thanks again for the review!  The changes will be in 04.

Regards,

Alia

 

RjS