The Session Initiation Protocol (SIP) P-Private-Network-Indication Private Header (P-Header)
draft-vanelburg-dispatch-private-network-ind-07

[Ballot comment]
Thank you for addressing the SecDir review comments. 

Thanks for addressing the prior discuss by explaining the risk of spoofing in section 1.2: I would like to understand what prevents spoofing the domain name used in this extension?  The rules included for setting and removing this use of this extension may be enough, but does rely on the security of the devices (proxies) and the network.  As such, it would be helpful to call spoofing out specifically and the mitigations for it in the security considerations section.  It would be helpful to see the set of mitigation described in one spot (Security Considerations).

And I found a couple of nits that would be helpful to correct:

Section 6.1.1 I recommend breaking the first sentence into multiple as it is a bit tough to read.

Security Considerations Section:  Can you add network before "elements" in the first sentence?  In other areas, elements typically refers to data.  Also, traffic should not have an "s" at the end. 
New:
  The private network indication defined in this document MUST only be
  used in the traffic transported between the network elements which are
  mutually trusted

[Ballot comment]
Please do address Spencer's comments and update the applicability section. It not entirely clear to me why we need to be publishing this document, but still, making it clear why we're publishing another P-header would be good.

[Ballot comment]

I've just a bunch of nits. My guess about Specer's
non-post-Snowden question is that probably loads of
IMS stuff assumes physical security, which may well
be questionable. I'd love to be shown that I'm wrong.
I doubt fixing that here is doable though.

I also think Kathleen's discuss is right - calling
out that anyone can spoof the header field values
that are allowed on their n/w would be good.

- 1.2: Is "closed" accurate there really? Just wondering.

- 1.2: RFC 3427 is obsoleted. Does that make any difference
to the applicability statement?  (Funny that the shepherd
write up says this passes the nit checker but the nit
checker in the tracker spots this and the ESP one below.)

- 1.3: Should the section title be "Background"?

- 3.6: I didn't know what Spec(T) meant. Maybe add a
reference to 3324 section 2.4?

- section 5: By "domain name" do you mean it has to be, or
just often is, a real DNS name?

- section 7: Does that syntax allow for i18n?

- section 8: RFC 2406 is obsoleted. That should be fixed.

- section 8: Don't you want to allow SIP/TLS too?

- section 8, para 1: Using "ensures the ..." is somewhat
optimistic isn't it? "needs to ensure the ..." would be
better I think.

- section 8: Also just wondering. Given that this header
field name is quite long and assuming for a moment that it
might be the only difference between private and public SIP
messages, might not the message sizes allow someone to
distinguish such SIP messages even if they are encrypted?
Worth noting? I'm not sure, but the example you give is 42
bytes long which could be a nice distinguisher if one
cared.

[Ballot comment]
I can't quite make myself ballot Discuss on this, but I've been through the Discuss criteria twice looking for justification for a Discuss. Please make good choices.

In this text: 1.2.  Applicability

  According to RFC 3427 [RFC3427], P-headers have a limited
  applicability.  Specifications of P-headers such as this RFC need to
  clearly document the useful scope of the proposal, and explain its
  limitations and why it is not suitable for the general use of SIP on
  the Internet.

RFC 3427 was obsoleted by RFC 5727, and since then we've also published RFC 6648 (as a BCP) that explicitly deprecated the use of P-headers in SIP. So, this paragraph would have been about right in 2008, but it doesn't describe reality today.

I'm fine with publishing this specification for a P-header because it's documenting established practice, and section 1.3 of the draft explains that, but I'd prefer that we not publish an RFC in 2014 that seems to say the draft authors were bound by RFC 3427 requirements that no longer apply.

There are, of course, other ways to address this comment, but chopping the first paragraph in 1.2 would work for me.

In this text: 8.  Security considerations

  The private network indication defined in this document MUST only be
  used in the traffics transported between the elements which are
  mutually trusted.  Traffic protection between network elements can be
  achieved by using the security protocols such as IPsec ESP [RFC2406]
  or sometimes by physical protection of the network. 

(I swear this isn't a post-Snowden question)

This draft was Publication-Requested in its current form because it matches existing deployments, if I'm understanding correctly. Do those existing deployments rely on physical protection of the network for traffic protection?

I'd feel better about allowing this loophole in 2014 if I knew it applied in target deployments.

[Ballot discuss]
Thank you for addressing the SecDir review comments.  I would like to understand what prevents spoofing the domain name used in this extension?  The rules included for setting and removing this use of this extension may be enough, but does rely on the security of the devices (proxies) and the network.  As such, it would be helpful to call spoofing out specifically and the mitigations for it in the security considerations section.  It would be helpful to see the set of mitigation described in one spot (Security Considerations).

[Ballot comment]
And I found a couple of nits that would be helpful to correct:

Section 6.1.1 I recommend breaking the first sentence into multiple as it is a bit tough to read.

Security Considerations Section:  Can you add network before "elements" in the first sentence?  In other areas, elements typically refers to data.  Also, traffic should not have an "s" at the end. 
New:
  The private network indication defined in this document MUST only be
  used in the traffic transported between the network elements which are
  mutually trusted

IESG/Authors:

IANA has reviewed draft-vanelburg-dispatch-private-network-ind-05.  Authors should review the comments and/or questions below.  Please report any inaccuracies and respond to any questions as soon as possible.

IANA's reviewer has the following comments/questions:

IANA understands that, upon approval of this document, there is a single action which IANA must complete.

In the Header Fields subregistry of the Session Initiation Protocol (SIP) Parameters registry located at:

http://www.iana.org/assignments/sip-parameters/

a single, new SIP header field is to be registered as follows:

Header Name: P-Private-Network-Indication
compact:
Reference: [ RFC-to-be ]

NOTE: The Header Fields subregistry requires Expert Review as per RFC5727.  IANA have sent this to the designated expert for review.  The DE, Adam
Roach, has approved this.

IANA understands that this is the only action required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed
until the document has been approved for publication as an RFC.
This message is only to confirm what actions will be performed.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (The Session Initiation Protocol (SIP) P-Private-Network-Indication Private-Header (P-Header)) to Informational RFC


The IESG has received a request from an individual submitter to consider
the following document:
- 'The Session Initiation Protocol (SIP) P-Private-Network-Indication
  Private-Header (P-Header)'
  as Informational
RFC

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2014-03-14. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  This document specifies the SIP P-Private-Network-Indication P-header
  used by the 3rd-Generation Partnership Project (3GPP).  The
  P-Private-Network-Indication indicates that the message is part of
  the message traffic of a private network, and identifies that private
  network.  A private network indication allows nodes to treat private
  network traffic according to a different set of rules than the set
  applicable to public network traffic.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-vanelburg-dispatch-private-network-ind/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-vanelburg-dispatch-private-network-ind/ballot/


No IPR declarations have been submitted directly on this I-D.

PROTO questionnaire for:  draft-vanelburg-dispatch-private-network-ind-09

To be Published as: Informational

Prepared by: Mary Barnes (mary.ietf.barnes@gmail.com) on 7 February 2014


  (1) What type of RFC is being requested (BCP, Proposed Standard,
      Internet Standard, Informational, Experimental, or Historic)? 
      Why is this the proper type of RFC?  Is this type of RFC indicated 
      in the title page header?

This document follows the SIP change process (RFC 3427) for defining P-headers.
The SIP change process allows publication of documents defining P-headers
to be published as Informational.  This RFC type is indicated on the title page.

    (2) The IESG approval announcement includes a Document Announcement
        Write-Up. Please provide such a Document Announcement Write-Up.
        Recent examples can be found in the "Action" announcements for
        approved documents. The approval announcement contains the
        following sections:

        Technical Summary:

This document specifies the SIP P-Private-Network-Indication P-header
used by the 3rd-Generation Partnership Project (3GPP).  The
P-Private-Network-Indication indicates that the message is part of
the message traffic of a private network, and identifies that private
network.  A private network indication allows nodes to treat private
network traffic according to a different set of rules than the set
applicable to public network traffic.
 
        Working Group Summary:
        Was the document considered in any WG, and if so, why was
        it not adopted as a work item there? Was there controversy
        about particular points that caused the WG to not adopt the
        document?
 
This document has been discussed in the DISPATCH WG.  The DISPATCH WG
does not progress any documents as WG documents.  The DISPATCH WG
selects one the following actions for contributions to the WG that have been
adequately reviewed and discussed:
- None in the case of work items for which there is inadequate interest or
feedback indicates that the work should not be progressed (e.g., it's a
bad idea or not within scope for RAI area or IETF)
- New work item in currently chartered WG
- New WG or mini-WG in the case where the deliverable is likely a
single document - e.g. a new SIP header
- IETF official BoF - typically for work items that are of broad interest
and potential impact within the RAI area and across areas.
- Individual/AD sponsored - for items limited in scope and applicability

Individual/AD sponsored was the consensus of the DISPATCH WG
for this document and the AD(s) agreed to progress the document. 
There was no controversy around this decision. 

        Document Quality
        Are there existing implementations of the protocol? Have a
        significant number of vendors indicated their plan to
        implement the specification? Are there any reviewers that
        merit special mention as having done a thorough review,
        e.g., one that resulted in important changes or a
        conclusion that the document had no substantive issues? If
        there was a MIB Doctor, Media Type or other expert review,
        what was its course (briefly)? In the case of a Media Type
        review, on what date was the request posted?

This document is required for the 3GPP/IMS specifications, thus any
vendor that implements the 3GPP specifications follows this specification. 
John Elwell thoroughly reviewed earlier versions of this document.
In addition, James Yu provided a detailed review and Paul Kyzivat
reviewed one of the more recent versions. 


        Personnel
        Who is the Document Shepherd? Who is the Responsible Area
        Director?

Mary Barnes (DISPATCH WG co-chair) is the Document Shepherd. 
Richard Barnes is the Responsible AD.

    (3) Briefly describe the review of this document that was
        performed by the Document Shepherd.  If this version of
        the document is not ready for publication, please explain
        why the document is being forwarded to the IESG.

The Document Shepherd has thoroughly reviewed this version of the document. 
     
    (4) Does the document Shepherd have any concerns about the depth
        or breadth of the reviews that have been performed?

There are no concerns about the depth or breadth of the reviews.

    (5) Do portions of the document need review from a particular
        or from broader perspective, e.g., security, operational
        complexity, AAA, DNS, DHCP, XML, or internationalization?
        If so, describe the review that took place.
No.

    (6) Describe any specific concerns or issues that the Document
        Shepherd has with this document that the Responsible Area Director
        and/or the IESG should be aware of? For example, perhaps he or
        she is uncomfortable with certain parts of the document,
        or has concerns whether there really is a need for it. In any
        event, if the interested community has discussed those issues
        and has indicated that it still wishes to advance the document,
        detail those concerns here.

There are no specific concerns or issues.

    (7) Has each author confirmed that any and all appropriate IPR
        disclosures required for full conformance with the provisions
        of BCP 78 and BCP 79 have already been filed. If not, explain why.

Yes.
 
    (8) Has an IPR disclosure been filed that references this document?
        If so, summarize any discussion and conclusion regarding the IPR
        disclosures.

No.

    (9) How solid is the consensus of the interested community behind this
        document? Does it represent the strong concurrence of a few
        individuals, with others being silent, or does the interested
        community as a whole understand and agree with it?

There is WG consensus that AD sponsored is the best approach for
progressing this document. No one has expressed concerns about its progression. 

    (10) Has anyone threatened an appeal or otherwise indicated extreme
        discontent? If so, please summarise the areas of conflict in
        separate email messages to the Responsible Area Director. (It 
        should be in a separate email because this questionnaire is
        publicly available.)

No.

    (11) Identify any ID nits the Document Shepherd has found in this
        document. (See http://www.ietf.org/tools/idnits/ and the
        Internet-Drafts Checklist). Boilerplate checks are not enough;
        this check needs to be thorough.

The document was checked using idnits 2.13.01  There are no nits to be
addressed.

    (12) Describe how the document meets any required formal review
        criteria, such as the MIB Doctor, media type, and URI type
        reviews.

Per the SIP change process, this document requires expert review
as it defines P-headers.  John Elwell performed an earlier expert
eview with additional review by other SIP experts more recently on the mailing list.

    (13) Have all references within this document been identified as
        either normative or informative?

Yes.

    (14) Are there normative references to documents that are not ready
        for advancement or are otherwise in an unclear state?
        If such normative references exist, what is the plan for their
        completion?

No.

    (15) Are there downward normative references references (see RFC 3967)?
        If so, list these downward references to support the Area Director
        in the Last Call procedure.

No.

    (16) Will publication of this document change the status of any
        existing RFCs? Are those RFCs listed on the title page header,
        listed in the abstract, and discussed in the introduction?
        If the RFCs are not listed in the Abstract and Introduction,
        explain why, and point to the part of the document where the
        relationship of this document to the other RFCs is discussed.
        If this information is not in the document, explain why the
        interested community considers it unnecessary.

No.

    (17) Describe the Document Shepherd's review of the IANA considerations
        section, especially with regard to its consistency with the body
        of the document. Confirm that all protocol extensions that the
        document makes are associated with the appropriate reservations
        in IANA registries. Confirm that any referenced IANA registries
        have been clearly identified. Confirm that newly created IANA
        registries include a detailed specification of the initial
        contents for the registry, that allocations procedures for future
        registrations are defined, and a reasonable name for the new
        registry has been suggested (see RFC 5226).

This document defines a new SIP header field: P-Private-Network-
Indication.  The document clearly indicates that this header field
needs to be registered in the SIP Parameters registry under the
Header Fields subregistry.

    (18) List any new IANA registries that require Expert Review for
        future allocations. Provide any public guidance that the IESG
        would find useful in selecting the IANA Experts for these new
        registries.

This document defines no new IANA registries. 

    (19) Describe reviews and automated checks performed by to validate 
        sections of the document written in a formal language, such as
        XML code, BNF rules, MIB definitions, etc.

The ABNF for this document was validated using Bill Fenner's ABNF web
parsing tool.

PROTO questionnaire for:  draft-vanelburg-dispatch-private-network-ind-09

To be Published as: Informational

Prepared by: Mary Barnes (mary.ietf.barnes@gmail.com) on 7 February 2014


  (1) What type of RFC is being requested (BCP, Proposed Standard,
      Internet Standard, Informational, Experimental, or Historic)? 
      Why is this the proper type of RFC?  Is this type of RFC indicated 
      in the title page header?

This document follows the SIP change process (RFC 3427) for defining P-headers.
The SIP change process allows publication of documents defining P-headers
to be published as Informational.  This RFC type is indicated on the title page.

    (2) The IESG approval announcement includes a Document Announcement
        Write-Up. Please provide such a Document Announcement Write-Up.
        Recent examples can be found in the "Action" announcements for
        approved documents. The approval announcement contains the
        following sections:

        Technical Summary:

This document specifies the SIP P-Private-Network-Indication P-header
used by the 3rd-Generation Partnership Project (3GPP).  The
P-Private-Network-Indication indicates that the message is part of
the message traffic of a private network, and identifies that private
network.  A private network indication allows nodes to treat private
network traffic according to a different set of rules than the set
applicable to public network traffic.
 
        Working Group Summary:
        Was the document considered in any WG, and if so, why was
        it not adopted as a work item there? Was there controversy
        about particular points that caused the WG to not adopt the
        document?
 
This document has been discussed in the DISPATCH WG.  The DISPATCH WG
does not progress any documents as WG documents.  The DISPATCH WG
selects one the following actions for contributions to the WG that have been
adequately reviewed and discussed:
- None in the case of work items for which there is inadequate interest or
feedback indicates that the work should not be progressed (e.g., it's a
bad idea or not within scope for RAI area or IETF)
- New work item in currently chartered WG
- New WG or mini-WG in the case where the deliverable is likely a
single document - e.g. a new SIP header
- IETF official BoF - typically for work items that are of broad interest
and potential impact within the RAI area and across areas.
- Individual/AD sponsored - for items limited in scope and applicability

Individual/AD sponsored was the consensus of the DISPATCH WG
for this document and the AD(s) agreed to progress the document. 
There was no controversy around this decision. 

        Document Quality
        Are there existing implementations of the protocol? Have a
        significant number of vendors indicated their plan to
        implement the specification? Are there any reviewers that
        merit special mention as having done a thorough review,
        e.g., one that resulted in important changes or a
        conclusion that the document had no substantive issues? If
        there was a MIB Doctor, Media Type or other expert review,
        what was its course (briefly)? In the case of a Media Type
        review, on what date was the request posted?

This document is required for the 3GPP/IMS specifications, thus any
vendor that implements the 3GPP specifications follows this specification. 
John Elwell thoroughly reviewed earlier versions of this document.
In addition, James Yu provided a detailed review and Paul Kyzivat
reviewed one of the more recent versions. 


        Personnel
        Who is the Document Shepherd? Who is the Responsible Area
        Director?

Mary Barnes (DISPATCH WG co-chair) is the Document Shepherd. 
Richard Barnes is the Responsible AD.

    (3) Briefly describe the review of this document that was
        performed by the Document Shepherd.  If this version of
        the document is not ready for publication, please explain
        why the document is being forwarded to the IESG.

The Document Shepherd has thoroughly reviewed this version of the document. 
     
    (4) Does the document Shepherd have any concerns about the depth
        or breadth of the reviews that have been performed?

There are no concerns about the depth or breadth of the reviews.

    (5) Do portions of the document need review from a particular
        or from broader perspective, e.g., security, operational
        complexity, AAA, DNS, DHCP, XML, or internationalization?
        If so, describe the review that took place.
No.

    (6) Describe any specific concerns or issues that the Document
        Shepherd has with this document that the Responsible Area Director
        and/or the IESG should be aware of? For example, perhaps he or
        she is uncomfortable with certain parts of the document,
        or has concerns whether there really is a need for it. In any
        event, if the interested community has discussed those issues
        and has indicated that it still wishes to advance the document,
        detail those concerns here.

There are no specific concerns or issues.

    (7) Has each author confirmed that any and all appropriate IPR
        disclosures required for full conformance with the provisions
        of BCP 78 and BCP 79 have already been filed. If not, explain why.

Yes.
 
    (8) Has an IPR disclosure been filed that references this document?
        If so, summarize any discussion and conclusion regarding the IPR
        disclosures.

No.

    (9) How solid is the consensus of the interested community behind this
        document? Does it represent the strong concurrence of a few
        individuals, with others being silent, or does the interested
        community as a whole understand and agree with it?

There is WG consensus that AD sponsored is the best approach for
progressing this document. No one has expressed concerns about its progression. 

    (10) Has anyone threatened an appeal or otherwise indicated extreme
        discontent? If so, please summarise the areas of conflict in
        separate email messages to the Responsible Area Director. (It 
        should be in a separate email because this questionnaire is
        publicly available.)

No.

    (11) Identify any ID nits the Document Shepherd has found in this
        document. (See http://www.ietf.org/tools/idnits/ and the
        Internet-Drafts Checklist). Boilerplate checks are not enough;
        this check needs to be thorough.

The document was checked using idnits 2.13.01  There are no nits to be
addressed.

    (12) Describe how the document meets any required formal review
        criteria, such as the MIB Doctor, media type, and URI type
        reviews.

Per the SIP change process, this document requires expert review
as it defines P-headers.  John Elwell performed an earlier expert
eview with additional review by other SIP experts more recently on the mailing list.

    (13) Have all references within this document been identified as
        either normative or informative?

Yes.

    (14) Are there normative references to documents that are not ready
        for advancement or are otherwise in an unclear state?
        If such normative references exist, what is the plan for their
        completion?

No.

    (15) Are there downward normative references references (see RFC 3967)?
        If so, list these downward references to support the Area Director
        in the Last Call procedure.

No.

    (16) Will publication of this document change the status of any
        existing RFCs? Are those RFCs listed on the title page header,
        listed in the abstract, and discussed in the introduction?
        If the RFCs are not listed in the Abstract and Introduction,
        explain why, and point to the part of the document where the
        relationship of this document to the other RFCs is discussed.
        If this information is not in the document, explain why the
        interested community considers it unnecessary.

No.

    (17) Describe the Document Shepherd's review of the IANA considerations
        section, especially with regard to its consistency with the body
        of the document. Confirm that all protocol extensions that the
        document makes are associated with the appropriate reservations
        in IANA registries. Confirm that any referenced IANA registries
        have been clearly identified. Confirm that newly created IANA
        registries include a detailed specification of the initial
        contents for the registry, that allocations procedures for future
        registrations are defined, and a reasonable name for the new
        registry has been suggested (see RFC 5226).

This document defines a new SIP header field: P-Private-Network-
Indication.  The document clearly indicates that this header field
needs to be registered in the SIP Parameters registry under the
Header Fields subregistry.

    (18) List any new IANA registries that require Expert Review for
        future allocations. Provide any public guidance that the IESG
        would find useful in selecting the IANA Experts for these new
        registries.

This document defines no new IANA registries. 

    (19) Describe reviews and automated checks performed by to validate 
        sections of the document written in a formal language, such as
        XML code, BNF rules, MIB definitions, etc.

The ABNF for this document was validated using Bill Fenner's ABNF web
parsing tool.

PROTO questionnaire for:  draft-vanelburg-dispatch-private-network-ind-09

To be Published as: Informational

Prepared by: Mary Barnes (mary.ietf.barnes@gmail.com) on 7 February 2014


  (1) What type of RFC is being requested (BCP, Proposed Standard,
      Internet Standard, Informational, Experimental, or Historic)? 
      Why is this the proper type of RFC?  Is this type of RFC indicated 
      in the title page header?

This document follows the SIP change process (RFC 3427) for defining P-headers.  The SIP change process allows publication of documents defining P-headers to be published as Informational.  This RFC type is indicated on the title page.

    (2) The IESG approval announcement includes a Document Announcement
        Write-Up. Please provide such a Document Announcement Write-Up.
        Recent examples can be found in the "Action" announcements for
        approved documents. The approval announcement contains the
        following sections:

        Technical Summary:

This document specifies the SIP P-Private-Network-Indication P-header
used by the 3rd-Generation Partnership Project (3GPP).  The
P-Private-Network-Indication indicates that the message is part of
the message traffic of a private network, and identifies that private
network.  A private network indication allows nodes to treat private
network traffic according to a different set of rules than the set
applicable to public network traffic.
 
        Working Group Summary:
        Was the document considered in any WG, and if so, why was
        it not adopted as a work item there? Was there controversy
        about particular points that caused the WG to not adopt the
        document?
 
This document has been discussed in the DISPATCH WG.  The DISPATCH WG does not progress any documents as WG documents.  The DISPATCH WG selects one the following actions for contributions to the WG that have been adequately reviewed and discussed:
- None in the case of work items for which there is inadequate interest or feedback indicates that the work should not be progressed (e.g., it's a bad idea or not within scope for RAI area or IETF)
- New work item in currently chartered WG
- New WG or mini-WG in the case where the deliverable is likely a single document - e.g. a new SIP header
- IETF official BoF - typically for work items that are of broad interest and potential impact within the RAI area and across areas.
- Individual/AD sponsored - for items limited in scope and applicability

Individual/AD sponsored was the consensus of the DISPATCH WG for this document and the AD(s) agreed to progress the document.  There was no controversy around this decision. 

        Document Quality
        Are there existing implementations of the protocol? Have a
        significant number of vendors indicated their plan to
        implement the specification? Are there any reviewers that
        merit special mention as having done a thorough review,
        e.g., one that resulted in important changes or a
        conclusion that the document had no substantive issues? If
        there was a MIB Doctor, Media Type or other expert review,
        what was its course (briefly)? In the case of a Media Type
        review, on what date was the request posted?

This document is required for the 3GPP/IMS specifications, thus any vendor that implements the 3GPP specifications follows this specification. 
John Elwell thoroughly reviewed earlier versions of this document. In addition, James Yu provided a detailed review and Paul Kyzivat reviewed one of the more recent versions. 


        Personnel
        Who is the Document Shepherd? Who is the Responsible Area
        Director?

Mary Barnes (DISPATCH WG co-chair) is the Document Shepherd.  Richard Barnes is the Responsible AD.

    (3) Briefly describe the review of this document that was
        performed by the Document Shepherd.  If this version of
        the document is not ready for publication, please explain
        why the document is being forwarded to the IESG.

The Document Shepherd has thoroughly reviewed this version of the document. 
     
    (4) Does the document Shepherd have any concerns about the depth
        or breadth of the reviews that have been performed?

There are no concerns about the depth or breadth of the reviews.

    (5) Do portions of the document need review from a particular
        or from broader perspective, e.g., security, operational
        complexity, AAA, DNS, DHCP, XML, or internationalization?
        If so, describe the review that took place.
No.

    (6) Describe any specific concerns or issues that the Document
        Shepherd has with this document that the Responsible Area Director
        and/or the IESG should be aware of? For example, perhaps he or
        she is uncomfortable with certain parts of the document,
        or has concerns whether there really is a need for it. In any
        event, if the interested community has discussed those issues
        and has indicated that it still wishes to advance the document,
        detail those concerns here.

There are no specific concerns or issues.

    (7) Has each author confirmed that any and all appropriate IPR
        disclosures required for full conformance with the provisions
        of BCP 78 and BCP 79 have already been filed. If not, explain why.

Yes.
 
    (8) Has an IPR disclosure been filed that references this document?
        If so, summarize any discussion and conclusion regarding the IPR
        disclosures.

No.

    (9) How solid is the consensus of the interested community behind this
        document? Does it represent the strong concurrence of a few
        individuals, with others being silent, or does the interested
        community as a whole understand and agree with it?

There is WG consensus that AD sponsored is the best approach for progressing this document. No one has expressed concerns about its progression. 

    (10) Has anyone threatened an appeal or otherwise indicated extreme
        discontent? If so, please summarise the areas of conflict in
        separate email messages to the Responsible Area Director. (It 
        should be in a separate email because this questionnaire is
        publicly available.)

No.

    (11) Identify any ID nits the Document Shepherd has found in this
        document. (See http://www.ietf.org/tools/idnits/ and the
        Internet-Drafts Checklist). Boilerplate checks are not enough;
        this check needs to be thorough.

The document was checked using idnits 2.13.01  There are no nits to be
addressed.

    (12) Describe how the document meets any required formal review
        criteria, such as the MIB Doctor, media type, and URI type
        reviews.

Per the SIP change process, this document requires expert review as it defines P-headers.  John Elwell performed an earlier expert review with additional review by other SIP experts more recently on the mailing list.

    (13) Have all references within this document been identified as
        either normative or informative?

Yes.

    (14) Are there normative references to documents that are not ready
        for advancement or are otherwise in an unclear state?
        If such normative references exist, what is the plan for their
        completion?

No.

    (15) Are there downward normative references references (see RFC 3967)?
        If so, list these downward references to support the Area Director
        in the Last Call procedure.

No.

    (16) Will publication of this document change the status of any
        existing RFCs? Are those RFCs listed on the title page header,
        listed in the abstract, and discussed in the introduction?
        If the RFCs are not listed in the Abstract and Introduction,
        explain why, and point to the part of the document where the
        relationship of this document to the other RFCs is discussed.
        If this information is not in the document, explain why the
        interested community considers it unnecessary.

No.

    (17) Describe the Document Shepherd's review of the IANA considerations
        section, especially with regard to its consistency with the body
        of the document. Confirm that all protocol extensions that the
        document makes are associated with the appropriate reservations
        in IANA registries. Confirm that any referenced IANA registries
        have been clearly identified. Confirm that newly created IANA
        registries include a detailed specification of the initial
        contents for the registry, that allocations procedures for future
        registrations are defined, and a reasonable name for the new
        registry has been suggested (see RFC 5226).

This document defines a new SIP header field: P-Private-Network-
Indication.  The document clearly indicates that this header field
needs to be registered in the SIP Parameters registry under the
Header Fields subregistry.

    (18) List any new IANA registries that require Expert Review for
        future allocations. Provide any public guidance that the IESG
        would find useful in selecting the IANA Experts for these new
        registries.

This document defines no new IANA registries. 

    (19) Describe reviews and automated checks performed by to validate 
        sections of the document written in a formal language, such as
        XML code, BNF rules, MIB definitions, etc.

The ABNF for this document was validated using Bill Fenner's ABNF web
parsing tool.