Re: [Insipid] AD Evaluation of draft-ietf-insipid-session-id-22

"Paul E. Jones" <paulej@packetizer.com> Wed, 25 May 2016 20:10 UTC

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From: "Paul E. Jones" <paulej@packetizer.com>
To: "Ben Campbell" <ben@nostrum.com>, draft-ietf-insipid-session-id.all@ietf.org, insipid@ietf.org
Date: Wed, 25 May 2016 20:10:40 +0000
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Subject: Re: [Insipid] AD Evaluation of draft-ietf-insipid-session-id-22
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We've been formulating a reply.  Coordination, time, etc.  But, a reply 
is coming very soon.

Paul

------ Original Message ------
From: "Ben Campbell" <ben@nostrum.com>
To: draft-ietf-insipid-session-id.all@ietf.org; insipid@ietf.org
Sent: 5/25/2016 3:57:28 PM
Subject: Re: [Insipid] AD Evaluation of draft-ietf-insipid-session-id-22

>Authors, any thoughts on these?
>
>Thanks!
>
>Ben.
>
>On 14 May 2016, at 19:46, Ben Campbell wrote:
>
>>  Hi,
>>
>>  This is my AD Evaluation of draft-ietf-insipid-session-id-22. I have 
>>a
>>  number of comments, and think that at least the "substantive" 
>>comments
>>  should be addressed prior to IETF last call.
>>
>>  Thanks!
>>
>>  Ben.
>>
>>  ------------- Substantive Comments:
>>
>>  - Abstract: The abstract makes it sound like the draft is
>>  multi-protocol. It's not, it's SIP specific. I recognize the idea is
>>  that the syntax could be used across signaling protocols, but this
>>  particular draft only defines how to do so for SIP. Please clarify.
>>
>>  - General
>>
>>  - 4.1, 2nd paragraph: Why is the requirement for version 4 or 5 UUIDs
>>  only a SHOULD? It seems like we should really avoid any sort of
>>  persistent identifies in the UUID. If we really need the SHOULD, 
>>please
>>  describe when it might be reasonable to choose otherwise.
>>
>>  - 4.2, 2nd paragraph: "such as when a UA first initiates a SIP 
>>request,"
>>
>>  Should that be a SIP INVITE request, or SIP dialog-initiating 
>>request?
>>
>>  -- 2nd to last paragraph: Is there a normative statement elsewhere 
>>than
>>  devices other than conference-focuses MUST NOT reuse UUIDs? (Also, 
>>the
>>  MUST in this paragraph belongs with the section on MDUs. If this text
>>  means to simply point out that the MDU section has this requirement,
>>  then please state it descriptively here.)
>>
>>  -- last paragraph: I'm a bit uncomfortable with making storage
>>  completely out of scope, due to the potential "information-at-rest"
>>  security or privacy implications. (I note that RFC7206 cites 6872 for
>>  this purpose).
>>
>>  - 6, paragraph 8: Has the working group discussed the privacy
>>  implications of requiring an endpoint to keep the same UUID after a
>>  redirect, refer, or INVITE-with-replaces? It may be that the peer and
>>  intermediaries already know the source of the 2nd dialog is the same
>>  that of the first, but I think it's a topic that needs some mention 
>>in
>>  the text.
>>
>>  -- paragraph 10: Both the MAY and MUST seem incorrect here. The MAY 
>>is a
>>  statement of fact, and the MUST is a description of rules elsewhere 
>>in
>>  the draft. I suggest using descriptive language for both.
>>
>>  -7, first paragraph: Does the assumption of no "special treatment" 
>>means
>>  the intermediary  passing the session-id unchanged? Removes it? 
>>Either?
>>
>>  -- 4th paragraph: What happens when a B2BUA that does not implement
>>  session-id aggregates responses? If it passes through the peer UUIDs
>>  unchanged, does anything break? Can the UAC be misled about the UUID 
>>of
>>  the resulting peer?
>>
>>  -- 3rd paragraph from end: I'm confused by "A non- redirected or
>>  rejected response", since responses neither get redirected or 
>>rejected.
>>  Do you mean a redirection response or a rejection response? (Perhaps
>>  using response code classes would be more clear.)
>>
>>  "MUST replace its own UUID" - In what message(s)?
>>
>>  -- 2nd to last paragraph: Why are the SHOULDs not MUSTs? Can you
>>  describe situations in which one might reasonably not follow the
>>  SHOULDs?
>>
>>  -- last paragraph: The first "MAY" seems like a statement of fact. Is
>>  the 2nd MAY appropriate? That is, intermediary allowed to _not_ do 
>>this,
>>  and let endpoints get out of sync?
>>
>>  -8, last paragraph: Why is the SHOULD not a MUST? When might one
>>  reasonably not follow it?
>>
>>  -9, 2nd paragraph: Does this assume that the conference is new to 
>>each
>>  subsequent MCU? That is, one would never use this approach to bridge 
>>two
>>  existing conferences that already have their own UUIDs?
>>
>>  - 10.3: Why doesn't the b2bua send a re-invite to update the uuid as 
>>in
>>  the next example?
>>
>>  - 10.5: Please don't use the name of a trademarked, commercial 
>>service
>>  in an RFC. Can you recast this as a "web-based conference service"?
>>
>>  Also, this should be clarified to be one of many ways to implement 
>>this
>>  use case, not necessarily a preferred way. (For example,  endpoints
>>  might initiate the INVITE requests toward the focus.)
>>
>>  - 10.7, first bullet: It seems highly unlikely that a 3pcc server 
>>would
>>  not be dialog stateful.
>>
>>  - 11: This section creates MUST level requirements for an 
>>implementation
>>  to be backwards compatible with a pre-standard, proprietary version.
>>  That seems to be a stretch. Did the working group really intend that 
>>an
>>  implementation could not choose not to implement this section?
>>
>>  -- 4th bullet: Wny isn't the presence or absence of remote-uuid
>>  sufficient for responses?
>>
>>  -- 5th bullet: This seems out of place; it's about non-compliant
>>  implementations of this document, not about backwards compatibility.
>>
>>  - 6th bullet: Why would an "old" implementation include "remote-uuid" 
>>at
>>  all?
>>
>>  - 12, first paragraph: The MUST here seems to conflict with the 
>>previous
>>  SHOULD about using UUID versions other than 4 or 5. (see previous
>>  comment).
>>
>>  -- 3rd paragraph: Is there an impact if something tampers with or 
>>lies
>>  about session-Id values?
>>
>>  - 15: Thank you for including this.
>>
>>  Editorial Comments and Nits:
>>
>>  -1, first paragraph: Please expand SIP on first mention.
>>
>>  - 4.2, 4th paragraph: Please expand PBX on first mention.
>>
>>  -- 2nd to last paragraph: This referes to conference focus, but most 
>>of
>>  the relevant section discusses MDUs. Please use consistent terms.
>>  (either may be okay, but "focus" probably better captures the 
>>signaling
>>  vs media role.)
>>
>>  -6, paragraph 9: What is meant by "negatively affect"? Is this 
>>allowed
>>  to affect the session in neutral or positive ways?
>>
>>  -- paragraph 11: Consider s/"MUST take care to ensure"/"MUST ensure".
>>  The "take care" part softens the message.
>>
>>  -- 2nd to last paragraph: Redundant normative statements. Consider
>>  making the first one descriptive, since the second is the more 
>>precise
>>  of the two. (This pattern repeats in section 7 paragraph 7)
>>
>>  - 7, 2nd paragraph: "which is why intermediaries" I think that's one
>>  reason why. There are likely others.
>>
>>  -- 7th paragraph: "If an intermediary receives a SIP message without 
>>a
>>  Session-ID header field or valid header field value..."
>>
>>  Does this mean either without session-id, or with session-Id but 
>>without
>>  a valid value? (As worded, the second part reads like it means 
>>without
>>  any valid header fields, but that doesn't make sense.)
>>
>>  -8, first paragraph: This seems redundant to previous sections.
>>
>>  10.1, paragraph before SIP detail: It's not really complete if you 
>>omit
>>  stuff :-)
>>
>>  10.3: There's no description of the initial re-invite.
>>
>>  11, paragraph 5: It's not clear what "that" refers to.
>>
>>
>>
>>
>>
>>
>>
>>
>>
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