[Last-Call] Re: RtgDir Last Call review: draft-ietf-lsvr-bgp-spf-39

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Hopefully, my response won’t be truncated like the original.
I’ve incorporated all the comments other than worrying about the early-allocation IANA values that are now being “deprecated”, as opposed to, “removed”. 
In most cases, I’ve used the suggested updates. 

  Hello,

       I have been selected as the Routing Directorate reviewer for this draft.
       The Routing Directorate seeks to review all routing or routing-related
       drafts as they pass through IETF last call and IESG review, and sometimes
       on special request. The purpose of the review is to provide assistance to
       the Routing ADs. For more information about the Routing Directorate, please
       see https://wiki.ietf.org/en/group/rtg/RtgDir

       Although these comments are primarily for the use of the Routing ADs, it
       would be helpful if you could consider them along with any other IETF Last
       Call comments that you receive, and strive to resolve them through
       discussion or by updating the draft.

       Document: draft-ietf-lsvr-bgp-spf-39
       Reviewer: Alvaro Retana
       Review Date: December 5, 2024
       IETF LC End Date: December 10, 2024
       Intended Status: Standards Track


       Summary:

       This document is basically ready for publication, but I have some concerns
       that I think should be resolved before publication.


       Comments:

       I was the Responsible AD for this document until -21, and reviewed -27.  I
       also participated in the WG's discussion of the last RtgDir review (-31).
       I based my review mainly on the diffs between -28 and -39.

       In general, this is a well-written document. Its revisions have improved
       the specification. Any remaining issues (see details below) should be easy
       to address.


       Major Issues:

       While I identified several issues as "major" (below -- mostly because of
       their Normative impact), I only want to highlight 2 here:

       (1) In §5.2.2.1 (BGP-LS Link NLRI Address Family Link Descriptor TLV), the
       case where multiple AFs are supported on the link is not described.  See
       comments around line 616.

       (2) The IANA Considerations subsection 8.2 (BGP-LS-SPF Assignments to
       BGP-LS NLRI and Attribute TLV Registry) addresses the fact that some
       early-allocated values are not required anymore, but rfc9552 doesn't
       specify a process to remove unrequired code points from the registry.  The
       code points should be marked as "Deprecated".  See comments around line
       1324.


       Minor Issues and Nits:  Please see details below.


       Thanks!

       Alvaro.


       [Line numbers from idnits.]

       ...
       182 1.2.  BGP Shortest Path First (SPF) Motivation
       ...
       219   With controller and route-reflector peering models, BGP SPF
       220   advertisement and distributed computation require a minimal number of
       221   sessions and copies of the NLRI since only the latest version of the
       222   NLRI from the originator is required (sed Section 4).  Given that

       [nit] s/sed/see

Fixed.



       ...
       304 3.  BGP Link-State (BGP-LS) Relationship
       ...
       315   The "BGP-LS NLRI and Attribute TLVs" registry [RFC9552] is shared
       316   between the BGP-LS SAFI and the BGP-LS-SPF SAFI.  However, the TLVs
       317   defined in this document are not applicable to the BGP-LS SAFI and
       318   BGP-LS SAFI consumers [RFC9552] MUST NOT result in the NLRI or the
       319   BGP-LS Attribute being considered malformed (section 5.2 of
       320   [RFC9552]).  The list of BGP-LS TLVs applicable to the BGP-LS-SPF
       321   SAFI are described in Section 5.2.  By default, the usage of other
       322   BGP-LS TLVs or extensions are ignored for the BGP-LS-SPF SAFI.
       323   However, this doesn't preclude the usage specification of these TLVs
       324   for the BGP-LS-SPF SAFI in future documents.

       [major] "...the TLVs defined in this document are not applicable to the
       BGP-LS SAFI and BGP-LS SAFI consumers [RFC9552] MUST NOT result in the NLRI
       or the BGP-LS Attribute being considered malformed (section 5.2 of
       [RFC9552])."

       This document cannot require any action from BGP-LS nodes.

       The text may have been an attempt to copy the specification in §5.1/rfc9552
       (not §5.2): "The presence of unknown or unexpected TLVs MUST NOT result in
       the NLRI or the BGP-LS Attribute being considered malformed."

       Suggestion>
       OLD>
       However, the TLVs defined in this document are not applicable to the
       BGP-LS SAFI and BGP-LS SAFI consumers [RFC9552] MUST NOT result in the
       NLRI or the BGP-LS Attribute being considered malformed (section 5.2
       of [RFC9552]).

       NEW>
       However, the TLVs defined in this document may not be applicable to
       the BGP-LS SAFI.  As specified in Section 5.1 of RFC9552, the presence
       of unknown or unexpected TLVs is required to not result in the NLRI or
       the BGP-LS Attribute being considered malformed.

Fixed.



       ...
       337 4.1.  BGP Single-Hop Peering on Network Node Connections
       ...
       347   An End-of-RIB (EoR) Marker Section 5.3 for the BGP-LS-SPF SAFI MAY be
       348   required from a peer prior to advertising the BGP-LS Link NLRI for
       349   the corresponding link to that peer.

       [nit] s/Section 5.3/(Section 5.3)/g
Fixed.


       [major, but it may just be me] "MAY be required from a peer"

       The Normative text sounds confusing even if "required" is in lowercase.

       The previous text (-28, for example) said "MAY be expected".  I agree that
       adding "from a peer" helps with clarity.

       s/MAY be required from a peer/MAY be expected from a peer/g

Ok - I've changed.



       ...
       498 5.2.1.1.  BGP-LS-SPF Node NLRI Attribute SPF Status TLV
       ...
       528   If a BGP SPF speaker received the Node NLRI but the SPF Status TLV is
       529   not received, then any previously received SPF status information is
       530   considered as implicitly withdrawn and the update is propagated to
       531   other BGP SPF speakers.  A BGP SPF speaker receiving a BGP Update
       532   containing a SPF Status TLV in the BGP-LS attribute [RFC9552] with a
       533   non-reserved value (3-254) that is unknown SHOULD be advertised to
       534   other BGP SPF speakers.  However, a BGP SPF speaker MUST NOT use the
       535   Status TLV in its SPF computation.  An implementation MAY log this
       536   condition for further analysis.  If the SPF Status TLV contains a
       537   reserved value (0 or 255) the TLV is considered malformed and is
       538   handled as described in Section 7.1.

       [major] "non-reserved value (3-254) that is unknown"

       If we're being strict, values 1 and 2 are also "non-reserved" (because they
       are assigned).  Instead of attaching a normative behavior to values that
       may change in the future (and require future documents to Update this one),
       use "unknown".

       s/a non-reserved value (3-254) that is unknown/an unknown value/g


Fixed (3 times for BGP-LS-SPF Node, Link, and Prefix NLRI).



       540 5.2.2.  Link NLRI Usage
       ...
       565   The link descriptors are described in table 4 of [RFC9552].
       566   Additionally, an address family link descriptor is defined to
       567   determine whether an unnumbered link can be used in the IPv4 SPF, the
       568   IPv6, or both (refer to Section 5.2.2.1).

       [nit] s/an address family link descriptor/the Address Family Link
       Descriptor TLV

Fixed.



       570   For a link to be used in SPF computation for a given address family,
       571   i.e., IPv4 or IPv6, both routers connecting the link MUST have
       572   matching addresses (i.e., interface addresses must match the neighbor
       573   addresses).

       [] Maybe it's just me, but "matching addresses" doesn't tell me what the
       characteristics of the addresses should be.  It sounds as if they are
       required to be the same.

       FWIW, the previous description was more explicit: "both routers connecting
       the link MUST have an address in the same subnet for that address family."

Fixed - I tried to not be too verbose here.



       ...
       588 5.2.2.1.  BGP-LS Link NLRI Address Family Link Descriptor TLV

       590   For unnumbered links, the address family cannot be ascertained from
       591   the endpoint link descriptors.  Hence, the Address Family (AF) Link
       592   Descriptor SHOULD be included with the Link Local/Remote Identifiers
       593   TLV for unnumbered links, so that the link can be used in the
       594   respective address family SPF.  If the Address Family Link Descriptor
       595   is not present for an unnumbered link, the link will not be used in
       596   the SPF computation for either address family.  If the Address Family
       597   Link Descriptor is present for a numbered link, the link descriptor
       598   will be ignored.  If the Address Family Link Descriptor TLV contains
       599   an undefined value (3-254), the link descriptor will be ignored.  If
       600   the Address Family Link Descriptor TLV contains a reserved value (0
       601   or 255) the TLV is considered malformed and is handled as described
       602   in Section 7.1.

       604      0                   1                   2                   3
       605      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       606     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       607     |   Type (TBD)                  |      Length (1 Octet)         |
       608     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       609     | Address Family|
       610     +-+-+-+-+-+-+-+-+

       612     Address Family Values: 0 - Reserved
       613                            1 - IPv4 SPF Computation
       614                            2 - IPv6 SPF Computation
       615                            3-254 - Undefined
       616                            255 - Reserved

       [minor] Why are the AFs called "IPvx SPF Computation" and not simply "IPvx"?

Ok - IPv4 and IPv6 Address Family


       [major] What about the case where multiple AFs are supported on the link?
       Should multiple TLVs be advertised, or should the length (which is not
       specified above) reflect the inclusion of more than one AF?


Added:

     Note that an unnumbered link can be used for both the IPv4 and IPv6
     SPF computation by advertising separate Address Family Link
     Descriptor TLVs for IPv4 and IPv6.


       ...
       752 5.3.  BGP-LS-SPF End of RIB (EoR) Marker

       754   The usage of the End-of-RIB (EoR) Marker [RFC4724] with the BGP-LS-
       755   SPF SAFI is somewhat different than the other BGP SAFIs.  Optionally,
       756   reception of the EoR marker MAY be required prior to advertising an
       757   LINK-NLRI for a given peer.  This is similar to OSPF's [RFC2328]
       758   requirement to not advertise an adjacency until database
       759   synchronization has completed.

       [major] "Optionally, reception of the EoR marker MAY be required..."

       This sentence is confusing because, at first, it sounds redundant
       ("Optionally" and "MAY" basically mean the same thing), but it is then
       mixed with a (possibly) *required* behavior (even if used in lowercase).

       In §4.1 I suggested using "MAY be expected from a peer".  That wording
       should be worked in here as well.  Also, the behavior is already specified
       in §4.1/§4.2, so there's no need to specify it here again.

       Suggestion>
       Reception of the EoR marker is optionally expected from a peer
       prior to advertising a Link NLRI for that peer.

Fixed.


       [major] "This is similar to OSPF's..."

       This is the one remaining sentence that compares BGP SPF to other
       protocols.  Not needed, please remove it.

Ok - I've removed.



       ...
       813 6.1.  BGP SPF NLRI Selection
       ...
       818   1.  NLRI self-originated from directly-connected BGP SPF peers are
       819       preferred.  This condition can be determined by comparing the BGP
       820       Identifiers in the received Local Node Descriptor and the BGP
       821       OPEN message for an active BGP session.  This rule assures that
       822       stale NLRI is updated even if a BGP-LS router loses its sequence
       823       number state due to a cold-start.  Note that once the BGP session
       824       goes down, the NLRI received is no longer considered as being
       825       from a directly connected BGP SPF peer.

       [minor] s/BGP-LS router/BGP SPF router

Fixed.



       ...
       899 6.3.  SPF Calculation based on BGP-LS-SPF NLRI
       ...
       1054              -  For unnumbered links to match during the IPv4 or IPv6
       1055                 SPF computation, Current-Link and Remote-Link's Address
       1056                 Family link descriptor must match address family of the
       1057                 IPv4 or IPv6 SPF computation, the Current--Link's Local
       1058                 Identifier MUST match the Remote-Link's Remote
       1059                 Identifier, and the Current-Link's Remote Identifier
       1060                 MUST the Remote-Link's Local Identifier.  Since the
       1061                 Link's Remote Identifier may not be known, a value of 0
       1062                 is considered a wildcard and will match any Current or
       1063                 Remote Link's Local Identifier (see TLV 258 [RFC9552]).

       [nit] s/Current-Link and Remote-Link's Address Family link descriptor/the
       Current-Link and Remote-Link's Address Family Link Descriptor TLV value


       [minor] s/the Current-Link's Remote Identifier MUST the Remote-Link's Local
       Identifier/the Current-Link's Remote Identifier MUST match the
       Remote-Link's Local Identifier

Fixed.



       ...
       1298 8.2.  BGP-LS-SPF Assignments to BGP-LS NLRI and Attribute TLV Registry

       1300   IANA has assigned five TLVs for BGP-LS-SPF NLRI in the "BGP-LS NLRI
       1301   and Attribute TLV" registry.  These TLV types include the SPF Status
       1302   TLV types, Address Famliy Link Descriptor TLV type, and Sequence
       1303   Number TLV type.

       1305     +==========+=================+=================================+
       1306     | TLV Code | Description     | Reference                       |
       1307     | Point    |                 |                                 |
       1308     +==========+=================+=================================+
       1309     | TBD      | Address Family  | Section 5.2.2.1, RFCXXXX ([this |
       1310     |          | Link Descriptor | document]).                     |
       1311     +----------+-----------------+---------------------------------+
       1312     | 1181     | Sequence Number | RFCXXXX ([this document]),      |
       1313     |          |                 | Section 5.2.4                   |
       1314     +----------+-----------------+---------------------------------+
       1315     | 1184     | SPF Status      | Section 5.2.1.1, RFCXXXX ([this |
       1316     |          |                 | document]), Section 5.2.2.2 and |
       1317     |          |                 | Section 5.2.3.1                 |
       1318     +----------+-----------------+---------------------------------+

       1320                       Table 1: NLRI Attribute TLVs

       1322   The early allocation assignments for the TLV types SPF Capability
       1323   (1180), IPv4 Prefix Length (1182), and IPv6 Prefix Length (1183) are
       1324   no longer required and can be removed.

       [major] RFC9552 doesn’t specify a process for removing unrequired code
       points from the registry.  Therefore, I believe the correct action in this
       document is to request that the code points be marked as “Deprecated."

       Note that §7.2/rfc9552 says that the "WG chairs may inform IANA that a
       deprecated code point can be completely deallocated (i.e., made available
       for new allocations) at any time after it has been deprecated if there is a
       shortage of unallocated code points in the registry."  I believe the "WG
       chairs" referred to here are the idr chairs -- and there's no shortage.


I just changed "removed" to "deprecated" and IANA after discussions with David Dong from IANA.

Thanks,
Acee


> On Dec 5, 2024, at 17:12, Alvaro Retana <aretana.ietf@xxxxxxxxx> wrote:
> 
> Hello,
> 
> I have been selected as the Routing Directorate reviewer for this draft.
> The Routing Directorate seeks to review all routing or routing-related
> drafts as they pass through IETF last call and IESG review, and sometimes
> on special request. The purpose of the review is to provide assistance to
> the Routing ADs. For more information about the Routing Directorate, please
> see https://wiki.ietf.org/en/group/rtg/RtgDir
> 
> Although these comments are primarily for the use of the Routing ADs, it
> would be helpful if you could consider them along with any other IETF Last
> Call comments that you receive, and strive to resolve them through
> discussion or by updating the draft.
> 
> Document: draft-ietf-lsvr-bgp-spf-39
> Reviewer: Alvaro Retana
> Review Date: December 5, 2024
> IETF LC End Date: December 10, 2024
> Intended Status: Standards Track
> 
> 
> Summary:
> 
> This document is basically ready for publication, but I have some concerns
> that I think should be resolved before publication.
> 
> 
> Comments:
> 
> I was the Responsible AD for this document until -21, and reviewed -27.  I
> also participated in the WG's discussion of the last RtgDir review (-31).
> I based my review mainly on the diffs between -28 and -39.
> 
> In general, this is a well-written document. Its revisions have improved
> the specification. Any remaining issues (see details below) should be easy
> to address.
> 
> 
> Major Issues:
> 
> While I identified several issues as "major" (below -- mostly because of
> their Normative impact), I only want to highlight 2 here:
> 
> (1) In §5.2.2.1 (BGP-LS Link NLRI Address Family Link Descriptor TLV), the
> case where multiple AFs are supported on the link is not described.  See
> comments around line 616.
> 
> (2) The IANA Considerations subsection 8.2 (BGP-LS-SPF Assignments to
> BGP-LS NLRI and Attribute TLV Registry) addresses the fact that some
> early-allocated values are not required anymore, but rfc9552 doesn't
> specify a process to remove unrequired code points from the registry.  The
> code points should be marked as "Deprecated".  See comments around line
> 1324.
> 
> 
> Minor Issues and Nits:  Please see details below.
> 
> 
> Thanks!
> 
> Alvaro.
> 
> 
> [Line numbers from idnits.]
> 
> ...
> 182 1.2.  BGP Shortest Path First (SPF) Motivation
> ...
> 219   With controller and route-reflector peering models, BGP SPF
> 220   advertisement and distributed computation require a minimal number of
> 221   sessions and copies of the NLRI since only the latest version of the
> 222   NLRI from the originator is required (sed Section 4).  Given that
> 
> [nit] s/sed/see
> 
> 
> 
> ...
> 304 3.  BGP Link-State (BGP-LS) Relationship
> ...
> 315   The "BGP-LS NLRI and Attribute TLVs" registry [RFC9552] is shared
> 316   between the BGP-LS SAFI and the BGP-LS-SPF SAFI.  However, the TLVs
> 317   defined in this document are not applicable to the BGP-LS SAFI and
> 318   BGP-LS SAFI consumers [RFC9552] MUST NOT result in the NLRI or the
> 319   BGP-LS Attribute being considered malformed (section 5.2 of
> 320   [RFC9552]).  The list of BGP-LS TLVs applicable to the BGP-LS-SPF
> 321   SAFI are described in Section 5.2.  By default, the usage of other
> 322   BGP-LS TLVs or extensions are ignored for the BGP-LS-SPF SAFI.
> 323   However, this doesn't preclude the usage specification of these TLVs
> 324   for the BGP-LS-SPF SAFI in future documents.
> 
> [major] "...the TLVs defined in this document are not applicable to the
> BGP-LS SAFI and BGP-LS SAFI consumers [RFC9552] MUST NOT result in the NLRI
> or the BGP-LS Attribute being considered malformed (section 5.2 of
> [RFC9552])."
> 
> This document cannot require any action from BGP-LS nodes.
> 
> The text may have been an attempt to copy the specification in §5.1/rfc9552
> (not §5.2): "The presence of unknown or unexpected TLVs MUST NOT result in
> the NLRI or the BGP-LS Attribute being considered malformed."
> 
> Suggestion>
> OLD>
>   However, the TLVs defined in this document are not applicable to the
>   BGP-LS SAFI and BGP-LS SAFI consumers [RFC9552] MUST NOT result in the
>   NLRI or the BGP-LS Attribute being considered malformed (section 5.2
>   of [RFC9552]).
> 
> NEW>
>   However, the TLVs defined in this document may not be applicable to
>   the BGP-LS SAFI.  As specified in Section 5.1 of RFC9552, the presence
>   of unknown or unexpected TLVs is required to not result in the NLRI or
>   the BGP-LS Attribute being considered malformed.
> 
> 
> 
> ...
> 337 4.1.  BGP Single-Hop Peering on Network Node Connections
> ...
> 347   An End-of-RIB (EoR) Marker Section 5.3 for the BGP-LS-SPF SAFI MAY be
> 348   required from a peer prior to advertising the BGP-LS Link NLRI for
> 349   the corresponding link to that peer.
> 
> [nit] s/Section 5.3/(Section 5.3)/g
> 
> 
> [major, but it may just be me] "MAY be required from a peer"
> 
> The Normative text sounds confusing even if "required" is in lowercase.
> 
> The previous text (-28, for example) said "MAY be expected".  I agree that
> adding "from a peer" helps with clarity.
> 
> s/MAY be required from a peer/MAY be expected from a peer/g
> 
> 
> 
> ...
> 498 5.2.1.1.  BGP-LS-SPF Node NLRI Attribute SPF Status TLV
> ...
> 528   If a BGP SPF speaker received the Node NLRI but the SPF Status TLV is
> 529   not received, then any previously received SPF status information is
> 530   considered as implicitly withdrawn and the update is propagated to
> 531   other BGP SPF speakers.  A BGP SPF speaker receiving a BGP Update
> 532   containing a SPF Status TLV in the BGP-LS attribute [RFC9552] with a
> 533   non-reserved value (3-254) that is unknown SHOULD be advertised to
> 534   other BGP SPF speakers.  However, a BGP SPF speaker MUST NOT use the
> 535   Status TLV in its SPF computation.  An implementation MAY log this
> 536   condition for further analysis.  If the SPF Status TLV contains a
> 537   reserved value (0 or 255) the TLV is considered malformed and is
> 538   handled as described in Section 7.1.
> 
> [major] "non-reserved value (3-254) that is unknown"
> 
> If we're being strict, values 1 and 2 are also "non-reserved" (because they
> are assigned).  Instead of attaching a normative behavior to values that
> may change in the future (and require future documents to Update this one),
> use "unknown".
> 
> s/a non-reserved value (3-254) that is unknown/an unknown value/g
> 
> 
> 
> 540 5.2.2.  Link NLRI Usage
> ...
> 565   The link descriptors are described in table 4 of [RFC9552].
> 566   Additionally, an address family link descriptor is defined to
> 567   determine whether an unnumbered link can be used in the IPv4 SPF, the
> 568   IPv6, or both (refer to Section 5.2.2.1).
> 
> [nit] s/an address family link descriptor/the Address Family Link
> Descriptor TLV
> 
> 
> 
> 570   For a link to be used in SPF computation for a given address family,
> 571   i.e., IPv4 or IPv6, both routers connecting the link MUST have
> 572   matching addresses (i.e., interface addresses must match the neighbor
> 573   addresses).
> 
> [] Maybe it's just me, but "matching addresses" doesn't tell me what the
> characteristics of the addresses should be.  It sounds as if they are
> required to be the same.
> 
> FWIW, the previous description was more explicit: "both routers connecting
> the link MUST have an address in the same subnet for that address family."
> 
> 
> 
> ...
> 588 5.2.2.1.  BGP-LS Link NLRI Address Family Link Descriptor TLV
> 
> 590   For unnumbered links, the address family cannot be ascertained from
> 591   the endpoint link descriptors.  Hence, the Address Family (AF) Link
> 592   Descriptor SHOULD be included with the Link Local/Remote Identifiers
> 593   TLV for unnumbered links, so that the link can be used in the
> 594   respective address family SPF.  If the Address Family Link Descriptor
> 595   is not present for an unnumbered link, the link will not be used in
> 596   the SPF computation for either address family.  If the Address Family
> 597   Link Descriptor is present for a numbered link, the link descriptor
> 598   will be ignored.  If the Address Family Link Descriptor TLV contains
> 599   an undefined value (3-254), the link descriptor will be ignored.  If
> 600   the Address Family Link Descriptor TLV contains a reserved value (0
> 601   or 255) the TLV is considered malformed and is handled as described
> 602   in Section 7.1.
> 
> 604      0                   1                   2                   3
> 605      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> 606     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> 607     |   Type (TBD)                  |      Length (1 Octet)         |
> 608     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> 609     | Address Family|
> 610     +-+-+-+-+-+-+-+-+
> 
> 612     Address Family Values: 0 - Reserved
> 613                            1 - IPv4 SPF Computation
> 614                            2 - IPv6 SPF Computation
> 615                            3-254 - Undefined
> 616                            255 - Reserved
> 
> [minor] Why are the AFs called "IPvx SPF Computation" and not simply "IPvx"?
> 
> 
> [major] What about the case where multiple AFs are supported on the link?
> Should multiple TLVs be advertised, or should the length (which is not
> specified above) reflect the inclusion of more than one AF?
> 
> 
> 
> ...
> 752 5.3.  BGP-LS-SPF End of RIB (EoR) Marker
> 
> 754   The usage of the End-of-RIB (EoR) Marker [RFC4724] with the BGP-LS-
> 755   SPF SAFI is somewhat different than the other BGP SAFIs.  Optionally,
> 756   reception of the EoR marker MAY be required prior to advertising an
> 757   LINK-NLRI for a given peer.  This is similar to OSPF's [RFC2328]
> 758   requirement to not advertise an adjacency until database
> 759   synchronization has completed.
> 
> [major] "Optionally, reception of the EoR marker MAY be required..."
> 
> This sentence is confusing because, at first, it sounds redundant
> ("Optionally" and "MAY" basically mean the same thing), but it is then
> mixed with a (possibly) *required* behavior (even if used in lowercase).
> 
> In §4.1 I suggested using "MAY be expected from a peer".  That wording
> should be worked in here as well.  Also, the behavior is already specified
> in §4.1/§4.2, so there's no need to specify it here again.
> 
> Suggestion>
>   Reception of the EoR marker is optionally expected from a peer
>   prior to advertising a Link NLRI for that peer.
> 
> 
> [major] "This is similar to OSPF's..."
> 
> This is the one remaining sentence that compares BGP SPF to other
> protocols.  Not needed, please remove it.
> 
> 
> 
> ...
> 813 6.1.  BGP SPF NLRI Selection
> ...
> 818   1.  NLRI self-originated from directly-connected BGP SPF peers are
> 819       preferred.  This condition can be determined by comparing the BGP
> 820       Identifiers in the received Local Node Descriptor and the BGP
> 821       OPEN message for an active BGP session.  This rule assures that
> 822       stale NLRI is updated even if a BGP-LS router loses its sequence
> 823       number state due to a cold-start.  Note that once the BGP session
> 824       goes down, the NLRI received is no longer considered as being
> 825       from a directly connected BGP SPF peer.
> 
> [minor] s/BGP-LS router/BGP SPF router
> 
> 
> 
> ...
> 899 6.3.  SPF Calculation based on BGP-LS-SPF NLRI
> ...
> 1054              -  For unnumbered links to match during the IPv4 or IPv6
> 1055                 SPF computation, Current-Link and Remote-Link's Address
> 1056                 Family link descriptor must match address family of the
> 1057                 IPv4 or IPv6 SPF computation, the Current--Link's Local
> 1058                 Identifier MUST match the Remote-Link's Remote
> 1059                 Identifier, and the Current-Link's Remote Identifier
> 1060                 MUST the Remote-Link's Local Identifier.  Since the
> 1061                 Link's Remote Identifier may not be known, a value of 0
> 1062                 is considered a wildcard and will match any Current or
> 1063                 Remote Link's Local Identifier (see TLV 258 [RFC9552])

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