[stir] Editorial comments on sections 3 and 4 of draft-ietf-stir-passport-divert-02 [was: drafts for london]

Christer Holmberg <christer.holmberg@ericsson.com> Tue, 06 March 2018 21:55 UTC

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From: Christer Holmberg <christer.holmberg@ericsson.com>
To: "Peterson, Jon" <jon.peterson@team.neustar>, "stir@ietf.org" <stir@ietf.org>
Thread-Topic: Editorial comments on sections 3 and 4 of draft-ietf-stir-passport-divert-02 [was: drafts for london]
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Date: Tue, 06 Mar 2018 21:55:52 +0000
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Subject: [stir] Editorial comments on sections 3 and 4 of draft-ietf-stir-passport-divert-02 [was: drafts for london]
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Hi Jon,

I see that the new version covers some of the issues that I raised previously. Thank you for that!

I did take a look at the new version (mostly focusing on Sections 3 and 4), and I have some editorial comments, mostly related to inconsistent terminology. But, there is also a couple of comments where I think we need more clarification.

(You may call some of my comments nit picking, but I personally think that fixing them would make the document easier to read)

---

Q1:

Throughout the document, you use different terminology for the claims. You at least use "claim", "array", "field".

I suggest to always use "claim", i.e., "div" claim, "dest" claim etc.

The fact that a claim might be an array is an encoding issue.


A few examples of where I identified this problem:

"occupy the "div" field in the new PASSporT."

(s/field/claim)


"...the original identifier for the called party in the "dest" array will become the "div" claim in the new PASSporT.  If the "dest" array of the original PASSporT contains multiple identifiers,..."

(s/array/claim)


"becomes the value of the "dest" array of the new PASSporT."

(s/array/claim)

---

Q2:

Throughout the document, you talk about "div" PASSporT, "div" PASSporT type, etc.

Please don't use the same name for the claim and the PASSPorT. Instead say something like "to the PASSporT carrying the "div" claim", "the diversion PASSporT", or something like that.

---

Q3:

Throughout the document, the text talks about "original PASSPorT".

Since there might be (at least in theory) multiple incoming PASSPorTs you need to define what "original" means.

---

Q4:

The text in Section 3 says:

"A PASSporT claims object containing "div""

I don't think we need to say "claims object". It is enough to just talk about PASSPorT (you do that elsewhere).

---

Q5:

The text in Section 3 says:

"These new PASSporT generated by retargeting entities MUST include the "div" PASSporT type,.."

Please explicitly indicate which header field includes the "div" type (i.e., the "ppt")

---

Q6:

The text in Section 3 says:

   "...for all PASSporTs using the "div" type the
   signature MUST be created with a credential with authority over the
   identity present in the "div" claim.  So for the example above, where
   the original "dest" is "12155551213", the signer of the new PASSporT
   object MUST have authority over that telephone number,..."

I think the text can be clarified in the following way:

   "...for all PASSporTs using the "div" type the
   signature MUST be created with a credential with authority over the
   identity present in the "div" claim, which means that the signer MUST
   have authority over the "dest" claim in the original PASSporT."

Because, I think this is a generic normative statement, not just a description of an example.
---

Q7:

The text in Section 4.1. says:

   "An authentication service only adds an Identity header field
   containing the "div" PASSporT type to an SIP request that already
   contains at least one Identity header field; it MUST NOT add a "div"
   request to an INVITE that contains no other Identity headers fields."

Is there a reason why you first say "SIP request" and then "INVITE"? Can't the "it MUST NOT add..." part be removed?

---

Q8:

In Section 4, when the new PASSPorT has been created and added to a SIP message, we need to clarify where the associated Identity header field is located in relation to other Identity header fields.

Alt A:

Identity: incoming_PASSPorT
Identity: div_PASSPorT

Alt B:

Identity: div_PASSPorT
Identity: incoming_PASSPorT

Regards,

Christer