Re: [Lsr] [Technical Errata Reported] RFC8919 (6630)

["Acee Lindem (acee)" <[e-mail]>]

LSR WG, 

This Errata is an outcome of the Flex-Algorithm discussion - is there any further comment? 

Thanks,
Acee

On 7/5/21, 5:48 PM, "RFC Errata System" <[e-mail]> wrote:

    The following errata report has been submitted for RFC8919,
    "IS-IS Application-Specific Link Attributes".

    --------------------------------------
    You may review the report below and at:
    https://www.rfc-editor.org/errata/eid6630

    --------------------------------------
    Type: Technical
    Reported by: Les Ginsberg <[e-mail]>

    Section: GLOBAL

    Original Text
    -------------
    Section 4.2:
    OLD

    If the SABM or UDABM Length in the Application Identifier Bit Mask
    is greater than 8, the entire sub-TLV MUST be ignored.

    (Later in Section 4.2)
    OLD

    If link attributes are advertised associated with zero-length
    Application Identifier Bit Masks for both standard applications and
    user-defined applications, then any standard application and/or any
    user-defined application is permitted to use that set of link
    attributes so long as there is not another set of attributes
    advertised on that same link that is associated with a non-zero-length
    Application Identifier Bit Mask with a matching Application Identifier
    Bit set.

    Section 6.2
    OLD

    Link attribute advertisements associated with zero-length Application
    Identifier Bit Masks for both standard applications and user-defined
    applications are usable by any application, subject to the
    restrictions specified in Section 4.2. If support for a new
    application is introduced on any node in a network in the presence
    of such advertisements, these advertisements are permitted to
    be used by the new application. If this is not what is intended,
    then existing advertisements MUST be readvertised with an explicit
    set of applications specified before a new application is introduced.


    Corrected Text
    --------------
    Section 4.2
    NEW

    If the SABM or UDABM Length in the Application Identifier Bit Mask
    is greater than 8, the entire sub-TLV MUST be ignored.

    When SABM or UDABM Length is non-zero and the L-flag is NOT set, all
    applications specified in the bit mask MUST use the link attribute
    advertisements in the sub-TLV.

    (Later in Section 4.2)
    NEW

    Link attributes MAY be advertised associated with zero-length
    Application Identifier Bit Masks for both standard applications and
    user-defined applications. Such link attribute advertisements MUST be
    used by standard applications and/or user defined applications when
    no link attribute advertisements with a non-zero-length Application
    Identifier Bit Mask and a matching Application Identifier Bit set are
    present for a given link. Otherwise, such link attribute advertisements
    MUST NOT be used.

    Section 6.2
    NEW

    Link attributes MAY be advertised associated with zero-length
    Application Identifier Bit Masks for both standard applications and
    user-defined applications. Such link attribute advertisements MUST be
    used by standard applications and/or user defined applications when
    no link attribute advertisements with a non-zero-length Application
    Identifier Bit Mask and a matching Application Identifier Bit set are
    present for a given link. Otherwise, such link attribute advertisements
    MUST NOT be used.

    Notes
    -----
    RFC 8919 defines advertising link attributes with zero
    length Standard Application Bit Mask (SABM) and zero length User
    Defined ApplicationBit Mask (UDABM) as a means of advertising link
    attributes that can be used by any application. However, the text uses
    the word "permitted", suggesting that the use of such advertisements
    is "optional". Such an interpretation could lead to interoperability
    issues and is not what was intended.

    The replacement text below makes explicit the specific conditions when
    such advertisements MUST be used and the specific conditions under
    which they MUST NOT be used.

    Instructions:
    -------------
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    --------------------------------------
    RFC8919 (draft-ietf-isis-te-app-19)
    --------------------------------------
    Title               : IS-IS Application-Specific Link Attributes
    Publication Date    : October 2020
    Author(s)           : L. Ginsberg, P. Psenak, S. Previdi, W. Henderickx, J. Drake
    Category            : PROPOSED STANDARD
    Source              : Link State Routing
    Area                : Routing
    Stream              : IETF
    Verifying Party     : IESG