Re: [Pce] Chair review of draft-lee-pce-flexible-grid

[Dhruv Dhody <[e-mail]>]

Hi Authors, 

Most of the comments that we received for the WSON RWA I-D [https://datatracker.ietf.org/doc/draft-ietf-pce-wson-rwa-ext/] during the IESG reviews are also applicable to this document. I would request the authors to also update this I-D and incorporate those comments while it is fresh in your minds. I am fine with this being done post WG adoption is resolved.

Thanks! 
Dhruv

--

Dhruv Dhody 
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> -----Original Message-----
> From: Pce [mailto:[e-mail]] On Behalf Of Adrian Farrel
> Sent: 19 February 2019 03:40
> To: [e-mail]
> Cc: [e-mail]
> Subject: [Pce] Chair review of draft-lee-pce-flexible-grid
> 
> Hi,
> 
> As this document is being polled for adoption, I thought I should review
> it.  There are a considerable number of nits, but nothing that prevents
> adoption in my view.  In the event that this document is adopted, I think
> the authors would do well to address the changes shortly afterwards.  If
> the document is not adopted but the authors want to continue with the work,
> they should pick up these nits.
> 
> Thanks,
> Adrian
> 
> ---
> 
> Please fix the RFC 2119 boilerplate to use the latest form...
> 
> 
>    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
>    "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
>    "OPTIONAL" in this document are to be interpreted as described in BCP
>    14 [RFC2119] [RFC8174] when, and only when, they appear in all
>    capitals, as shown here.
> 
> ....You'll need to add a reference to RFC 8174
> 
> ---
> 
> idnits shows a lot of issues with references. It is not hard to run idnits
> so please get into the habit of running it before you ask for WG adoption.
> 
> For your convenience, here are all of the issues
> 
>   == Missing Reference: 'RFC3209' is mentioned on line 318, but not
>      defined
> 
>   == Unused Reference: 'RFC2863' is defined on line 654, but no explicit
>      reference was found in the text
> 
>   == Unused Reference: 'RFC6566' is defined on line 683, but no explicit
>      reference was found in the text
> 
>   == Unused Reference: 'RFC7420' is defined on line 687, but no explicit
>      reference was found in the text
> 
>   == Unused Reference: 'RFC7446' is defined on line 692, but no explicit
>      reference was found in the text
> 
>   == Unused Reference: 'RFC5521' is defined on line 708, but no explicit
>      reference was found in the text
> 
>   == Unused Reference: 'RFC6205' is defined on line 712, but no explicit
>      reference was found in the text
> 
>   == Unused Reference: 'RFC7689' is defined on line 719, but no explicit
>      reference was found in the text
> 
>   == Unused Reference: 'RFC7688' is defined on line 722, but no explicit
>      reference was found in the text
> 
>   == Unused Reference: 'RFC7581' is defined on line 731, but no explicit
>      reference was found in the text
> 
>   ** Downref: Normative reference to an Informational RFC: RFC 7698
> 
> The last issue is a warning, and you can keep the downwards reference if
> you think it is the right thing to do.
> 
> ---
> 
> Please check that all abbreviations are expanded on first use.
> 
> I see:
> 
> ERO
> PCE
> 
> ---
> 
> Move the first sentence of paragraph 4 of Section 3 down to the end of
> that paragraph so that the use of the term "flexi-grid" comes after it has
> been explained.
> 
> ---
> 
> Section 3 has
> 
>    This document provides PCEP extensions to support Routing and
>    Spectrum Assignment (RSA) in in Spectrum Switched Optical Networks
>    (SSON)[RFC7698].
> 
> s/in in/
> s/(SSON)[RFC7698]/(SSON} [RFC7698]/
> 
> The terms RSA and SSON are, of course, defined in RFC 7698. But the terms
> come as a surprise in this document. Perhaps you could insert a short
> paragraph above this one to say...
> 
>    The terms "Routing and Spectrum Assignment" (RSA) is introduced in
>    [RFC7698] to refer to blah blah.  The term "Spectrum Switched
>    Optical Networks" is also introduced in [RFC7698] and indicates a
>    network that is blah blah blah.
> 
> That would leave you with
> 
>    This document provides PCEP extensions to support RSA in SSONs.
> 
> ---
> 
> Section 3
> 
> s/extensions are going to be specified/extensions are specified/
> 
> ---
> 
> Section 4
> 
> Bullet b) has a second sentence (beginning "This document aligns...") that
> doesn't seem specific to that bullet. Maybe it belongs at the top of the
> section.
> 
> ---
> 
> Section 4 has
> 
>    Additionally, given a range of potential spectrums to allocate, the
>    request SHOULD convey the heuristic / mechanism to the allocation.
> 
> The reader is left wondering how to meet that "SHOULD" and also why to
> vary that "SHOULD".
> 
> ---
> 
> Section 4 needs a reference to RFC 5511 to explain the notation.
> 
> ---
> 
> Section 4
> 
>    If the SA object is present in the request, it MUST be encoded after
>    the ENDPOINTS object.
> 
> I think that should be 'GENERALIZED ENDPOINTS object'
> 
> ---
> 
> Section 4 has
> 
>    The following new flags SHOULD be set
> 
> But I think you are equally happy for the bit to be set or cleared.
> 
> ---
> 
> 4.1
> 
>    This TLV
>    MUST NOT be used when the M bit is cleared.
> 
> I think you may mean...
> 
>    SHOULD NOT be present and MUST be ignored
> 
> ---
> 
> I think you are going to need an IANA registry for the Frequency-Slot
> Assignment (FSA) Method.
> 
> ---
> 
> 4.1 is going to need an explanation of what the 'n' parameter is.
> 
> ---
> 
> 4.1
> 
>       -  S bit not supported: a PathErr MUST be generated with the
>          Error Code "Routing Problem" (24) with error sub-code
>          "Unsupported Frequency slot Selection Symmetry value" (TDB).
> 
> This is a bit unclear. Presumably the issue is "S bit clear not supported".
> You might consider reversing the meaning of the S bit and then this would
> be a lot clearer.
> 
> ---
> 
> Please distinguish the different TBDs as TBD1, TBD2, etc.
> 
> (And note you have several cases of "TDB")
> 
> ---
> 
> 4.1
> 
>    As defined in
>    [RFC7570], the R bit reflects the LSP_REQUIRED_ATTRIBUTE and
>    LSP_ATTRIBUTE semantic defined in [RFC5420], and it SHOULD be set
>    accordingly.
> 
> It is not clear what R bit you are referring to.
> 
> ---
> 
> 4.1
> 
>    A Frequency Slot Selection TLV can be constructed by a node and
>    added to an ERO Hop Attributes subobject in order to be processed
>    by downstream nodes (transit and egress).  As defined in
>    [RFC7570], the R bit reflects the LSP_REQUIRED_ATTRIBUTE and
>    LSP_ATTRIBUTE semantic defined in [RFC5420], and it SHOULD be set
>    accordingly.
> 
>    Once a node properly parses the Spectrum Selection sub-TLV
>    received in an ERO Hop Attributes subobject, the node use the
>    indicated spectrum assignment method (at that hop) for the LSP.
>    In addition, the node SHOULD report compliance by adding an RRO
>    Hop Attributes subobject with the WSON Processing Hop Attribute
>    TLV (and its sub-TLVs) that indicate the utilized method.
>    Frequency-Slot Selection TLVs carried in an RRO Hop Attributes
>    subobject are subject to [RFC7570] and standard RRO processing;
>    see [RFC3209].
> 
> There's something odd here.
> 
> - Doesn't this section say/imply that the Frequency-Slot Selection TLV
>   belongs in the Spectrum Assignment object? Why are you talking about
>   TLVs in the Hop Attribute TLV and the ERO Hop Attributes subobject?
>   Maybe the first paragraph here should read...
>   A Frequency Slot Selection TLV can also be constructed by a node...
> 
> - Why are you talking about the Spectrum Selection sub-TLV? Doesn't that
>   belong in Section 5?
> 
> ---
> 
> 4.2
> 
>    For any request that contains a Frequency-slot assignment, the
>    requester (PCC) MUST be able to specify a restriction on the
>    frequency-slots to be used.
> 
> I think you can s/MUST/must/
> 
> ---
> 
> 4.2
> 
>    <Frequency-lot Restriction Constraint> ::=
> 
>                   <Action> <Count> <Reserved>
> 
>                   (<Link Identifiers> <Freq-slot Restriction>)...
> 
> I don't think you need to list every field of the frequency slot TLV in
> the RBNF, and in particular you should not list the reserved field.
> 
> ---
> 
> 4.2
> 
>    Note that a PCC MAY add a spectrum restriction that applies to all
>    links by setting the Count field to zero and specifying just a set
>    of spectrums.
> 
> I think s/spectrum/frequency slot/   twice
> 
> ---
> 
> 4.2
> 
>    and Section 3.3.1 for the Spectrum Restriction Field encoding,
>    respectively.
> 
> Why do you point us at the definition of this field?
> 
> ---
> 
> 4.2.1 broken reference
> 
> ---
> 
> 5.
> 
>    The Spectrum Allocation TLV type is TBD, recommended value is TBD.
> 
> No need to recommend a value of TBD :-)
> 
> ---
> 
> 5.
> 
>    The type
>    value of the Spectrum Restriction Constraint TLV is TBD by IANA.
> 
> This seems out of place and is the first mention of this TLV.
> 
> ---
> 
> Section 7 could use some external references.
> 
> ---
> 
> Section 8
> 
>    IANA maintains a registry of PCEP parameters. IANA has made
>    allocations from the sub-registries as described in the following
>    sections.
> 
> Hmmm, I think IANA has not actually made these allocations. You should say
> "IANA is requested to make allocations..."
> 
> ---
> 
> I think the titles of 9.1 and 9.2 may be reversed.
> 
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