Extensions to the Path Computation Element Communication Protocol (PCEP) for Route Exclusions
draft-ietf-pce-pcep-xro-06

[Ballot comment]
The security considerations section notes that

  The new exclude route mechanisms defined in this document allow
  finer and more specific control of the path computed by a PCE. Such
  control increases the risk if a PCEP message is intercepted,
  modified, or spoofed. Therefore, the security techniques described
  in [PCEP] are considered more important.

The phrase "increases the risk" begs the question "what risk?"  After reviewing
pce-pcep-12, I would hazard a guess that the increases in risk are limited to
PCEP Privacy (section 10.2 of pce-pcep) and possibly the DOS attacks described
under Request Input Shaping/Policing (section 10.3.2 of pce-pcep).  If my analysis
is correct, it would be nice to expand on "risk" and explicitly identify the concerns.
If other risks are impacted by this specification, that would be very helpful as well.

[Ballot discuss]
Need 4 byte ASN support.

3.1.1 - this is kindof odd defn:

" The L bit of the PKS subobject in the XRO is defined as follows.

  L
    The L bit MUST be ignored.
"


I'd beef up the security section w/ more from 3.1.1 but, I get both sections as is.

[Ballot comment]
Section 1, third paragraph:

In order to achieve path computation for a
  secondary (backup) path, a PCE may act as a PCC to request another

Incomplete sentence.

[Ballot comment]
The Manageability Consideration section includes a reference to a PCEP MIB document:

  'A MIB module for management of the PCEP is specified in a separate
  document. This MIB module allows examination of individual PCEP
  messages, in particular requests, responses and errors.

  The MIB module MUST be extended to include the ability to view the
  route exclusion extensions defined in this document.'

Actually right now there is no PCEP MIB in works. The WG is indeed working on a MIB document http://www.ietf.org/internet-drafts/draft-ietf-pce-disc-mib-02.txt but the approach taken there is to manage the PCE Discovery process and results, without reference to a PCEP. If a PCEP MIB will be the object of future work the text needs to be changed accordingly to avoid confusion.

[Ballot discuss]
The Manageability Consideration section includes a reference to a PCEP MIB document:

  'A MIB module for management of the PCEP is specified in a separate
  document. This MIB module allows examination of individual PCEP
  messages, in particular requests, responses and errors.

  The MIB module MUST be extended to include the ability to view the
  route exclusion extensions defined in this document.'

Actually right now there is no PCEP MIB in works AFAIK. The WG is indeed working on a MIB document http://www.ietf.org/internet-drafts/draft-ietf-pce-disc-mib-02.txt but the approach taken there is to manage the PCE Discovery process and results, without reference to a PCEP. If a PCEP MIB will be the object of future work the text needs to be changes accordingly to avoid confusion.

IANA Last Call comments:

NOTE: IANA has a question about action #2.

Action #1 (Section 4.2):

Upon approval of this document, the IANA will make the following
assignments in the "Path Computation Element Protocol (PCEP)"
registry to be created by [RFC-ietf-pce-pcep-12] at
http://www.iana.org/assignments/TBD-PCEP

Registry Name: PCEP Objects

Object Name Reference
Class
---------+-----------------------------------------------+--------------
TBD-17 | XRO | [RFC-pce-pcep-xro-05]
| Object-Type |
| 1: Route exclusion | [RFC-pce-pcep-xro-05]
| Sub-objects |
| 1 IPv4 prefix | [RFC3209]
| 2 IPv6 prefix | [RFC3209]
| 4 Unnumbered Interface ID | [RFC3477]
| 32 Autonomous system number | [RFC3209]
| 34 SRLG | [RFC4874]
| 64 IPv4 Path Key | [PCE-PATH-KEY]
| 65 IPv6 Path Key | [PCE-PATH-KEY]


Action #2 (Section 4.2):

QUESTION: Is the subobject “Explicit Exclusion Route subobject (EXRS)”
a sub-registration of object type “Include Route”?


Action #3 (Section 4.3):

Upon approval of this document, the IANA will make the following
assignment in the "Path Computation Element Protocol (PCEP)"
registry to be created by [RFC-ietf-pce-pcep-12] at
http://www.iana.org/assignments/TBD-PCEP

Registry Name: Error Types and Values

Error
Type Meaning Reference
-------+----------------------------------------------+---------
11 | Unrecognized EXRS subobject | [RFC-pce-pcep-xro-05]


Action #4 (Section 4.4):

Upon approval of this document, the IANA will create the following
registry at http://www.iana.org/assignments/TBD-PCEP

Registry Name: Exclude Route Flags
Registration Procedures: IETF Consensus

Registry:
Bit | Name | Description | Reference
-----------+----------+-----------------------+---------------
0-14 | Unassigned
15 | F-bit | Fail bit | [RFC-pce-pcep-xro-05]


We understand the above to be the only IANA Actions for this
document.

PROTO writeup by JP Vasseur:

Here is the proto write-up for draft-ietf-pce-pcep-xro-05.txt

Intended status : Standards Track

> (1.a)  Who is the Document Shepherd for this document?  Has the
>        Document Shepherd personally reviewed this version of the
>        document and, in particular, does he or she believe this
>        version is ready for forwarding to the IESG for publication?

JP Vasseur is the document shepherd and has reviewed the document. He thinks that the document is ready to be forwarded to the IESG for publication.

> (1.b)  Has the document had adequate review both from key WG members
>        and from key non-WG members?  Does the Document Shepherd have
>        any concerns about the depth or breadth of the reviews that
>        have been performed?

The document has been discussed and reviewed by several key WG members, with no review of non WG members that has been considered necessary.

> (1.c)  Does the Document Shepherd have concerns that the document
>        needs more review from a particular or broader perspective,
>        e.g., security, operational complexity, someone familiar with
>        AAA, internationalization or XML?

No concerns.

> (1.d)  Does the Document Shepherd have any specific concerns or
>        issues 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 WG has discussed those issues and has indicated
>        that it still wishes to advance the document, detail those
>        concerns here.  Has an IPR disclosure related to this document
>        been filed?  If so, please include a reference to the
>        disclosure and summarize the WG discussion and conclusion on
>        this issue.

No specific concern about this document. The solution specified in this document has a good support in the WG, and satisfies a well specified requirement for the PCEP protocol (RFC4657).

There was no filed IPR disclosure related to this document.

> (1.e)  How solid is the WG consensus behind this document?  Does it
>        represent the strong concurrence of a few individuals, with
>        others being silent, or does the WG as a whole understand and
>        agree with it?

Good consensus. No concern or additional comments received during WG Last Call.

> (1.f)  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
>        entered into the ID Tracker.)

No threats. No discontent.

> (1.g)  Has the Document Shepherd personally verified that the
>        document satisfies all ID nits?  (See
>        http://www.ietf.org/ID-Checklist.html and
>        http://tools.ietf.org/tools/idnits/).  Boilerplate checks are
>        not enough; this check needs to be thorough.  Has the document
>        met all formal review criteria it needs to, such as the MIB
>        Doctor, media type and URI type reviews?

The Document has been checked.

> (1.h)  Has the document split its references into normative and
>        informative?  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
>        strategy for their completion?  Are there normative references
>        that are downward references, as described in [RFC3967]?  If
>        so, list these downward references to support the Area
>        Director in the Last Call procedure for them [RFC3967].

References split.
No downrefs. The normative reference is intended to follow a Standard Track:

[PCE-PATH-KEY] R. Bradford, JP Vasseur, and A. Farrel, "Preserving
            Topology Confidentiality in Inter-Domain Path Computation
            using a key based mechanism", draft-ietf-pce-path-key
            (work in progress).

> (1.i)  Has the Document Shepherd verified that the document IANA
>        consideration section exists and is consistent with the body
>        of the document?  If the document specifies protocol
>        extensions, are reservations requested in appropriate IANA
>        registries?  Are the IANA registries clearly identified?  If
>        the document creates a new registry, does it define the
>        proposed initial contents of the registry and an allocation
>        procedure for future registrations?  Does it suggest a
>        reasonable name for the new registry?  See [RFC2434].  If the
>        document describes an Expert Review process has Shepherd
>        conferred with the Responsible Area Director so that the IESG
>        can appoint the needed Expert during the IESG Evaluation?

The document specifies PCEP protocol extensions and a IANA section exists that makes use of the same language as the PCEP specification.

Note that to help ensure consistent allocation of protocol codepoints, a temporary (non-definitive) registry is maintained at www.olddog.co.uk/pcep-codepoints.txt


> (1.j)  Has the Document Shepherd verified that sections of the
>        document that are written in a formal language, such as XML
>        code, BNF rules, MIB definitions, etc., validate correctly in
>        an automated checker?

No such formal language is used.

> (1.k)  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
>          Relevant content can frequently be found in the abstract
>          and/or introduction of the document.  If not, this may be
>          an indication that there are deficiencies in the abstract
>          or introduction.

  The Path Computation Element (PCE) defined in [RFC4655] is an entity
  that is capable of computing a network path or route based on a
  network graph, and applying computational constraints. A Path
  Computation Client (PCC) may make requests to a PCE for paths to be
  computed.

  When a PCC requests a PCE for a route, it may be useful for the PCC
  to specify abstract nodes, resources, and Shared Risk Link Groups
  (SRLGs) that are to be explicitly excluded from the route.

  For example, disjoint paths for inter-domain LSPs may be computed by
  cooperation between PCEs, each of which computes segments of the
  paths across one domain. In order to achieve path computation for a
  secondary (backup) path, a PCE may act as a PCC to request another

  PCE for a route that must be node/link/SRLG disjoint from the
  primary (working) path. Another example is where a network operator
  wants a path to avoid specified nodes for administrative reasons,
  perhaps because the specified nodes will be out-of-services in the
  near future.

  [RFC4657] specifies generic requirements for a communication
  protocol between PCCs and PCEs. Generic constraints described in
  [RFC4657] include route exclusions for links, nodes, and SRLGs. That
  is, the requirement for support of route exclusions within the PCC-
  PCE communication protocol is already established.

  The PCE communication protocol (PCEP) is designed as a communication
  protocol between PCCs and PCEs and is defined in [PCEP]. This
  document presents PCEP extensions to satisfy the requirements for
  route exclusions as described in Sections 5.1.4 and 5.1.16 of
  [RFC4657].

  Note that MPLS-TE and GMPLS signaling extensions for communicating
  route exclusions between network nodes for specific Label Switched
  Paths (LSPs) are described in [RFC4874]. Route exclusions may be
  specified during provisioning requests for specific LSPs by setting
  the mplsTunnelHopInclude object of MPLS-TE-STD-MIB defined in
  [RFC3812] to false (2).

>        Working Group Summary
>          Was there anything in WG process that is worth noting?  For
>          example, was there controversy about particular points or
>          were there decisions where the consensus was particularly
>          rough?

The PCE WG has good consensus with no disagreement.

>        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?

There is one known implementation of this document with several other unknown implementations. An interoperability event (ISOCRE) with multiple implementations is planned.