Re: [OSPF] Alexey Melnikov's Discuss on draft-ietf-ospf-segment-routing-extensions-23: (with DISCUSS and COMMENT)

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

Hi Alexey

These all seem to be valid comments except for the one on byte order. Note
that section 3.1 of RFC 2360 already states that IETF document packet
encodings are in Network-Byte Order (NBO).
https://www.ietf.org/rfc/rfc2360.txt

Typically, we have not defined Reserved field usage. However, I guess we
could say that they SHOULD be set to 0 on transmission and MUST be ignored
on reception. This will allow for future reuse in a backward compatible
manner. 

Thanks,
Acee 





On 12/13/17, 5:47 AM, "Alexey Melnikov" <[e-mail]> wrote:

>Alexey Melnikov has entered the following ballot position for
>draft-ietf-ospf-segment-routing-extensions-23: Discuss
>
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>
>
>----------------------------------------------------------------------
>DISCUSS:
>----------------------------------------------------------------------
>
>This is generally a clearly written document, but it needs a few minor
>changes
>before I can recommend its approval for publication.
>
>1) In Section 3.2:
>
>   o  When a router receives multiple overlapping ranges, it MUST
>      conform to the procedures defined in
>      [I-D.ietf-spring-conflict-resolution].
>
>RFC 2119 keyword usage makes the reference a Normative reference, yet it
>is
>currently listed as informative.
>
>3.4.  SRMS Preference TLV
>
>   The Segment Routing Mapping Server Preference TLV (SRMS Preference
>   TLV) is used to advertise a preference associated with the node that
>   acts as an SR Mapping Server.  The role of an SRMS is described in
>   [I-D.ietf-spring-segment-routing-ldp-interop].
>
>As draff-ietf-spring-segment-routing-ldp-interop needs to be read in
>order to
>understand what SR Mapping Server is, this reference must also be
>Normative.
>
>  SRMS preference is defined in [I-D.ietf-spring-conflict-resolution].
>
>This just confirms that this reference must be Normative.
>
>2) In Section 3.1:
>
>   When multiple SR-Algorithm TLVs are received from a given router, the
>   receiver SHOULD use the first occurrence of the TLV in the Router
>   Information LSA.  If the SR-Algorithm TLV appears in multiple Router
>   Information LSAs that have different flooding scopes, the SR-
>   Algorithm TLV in the Router Information LSA with the area-scoped
>   flooding scope SHOULD be used.  If the SR-Algorithm TLV appears in
>   multiple Router Information LSAs that have the same flooding scope,
>   the SR-Algorithm TLV in the Router Information (RI) LSA with the
>   numerically smallest Instance ID SHOULD be used and subsequent
>   instances of the SR-Algorithm TLV SHOULD be ignored.
>
>In the last 2 sentences: why are you using SHOULD (twice) instead of
>MUST? This
>seems to affect interoperability.
>
>(I think there is similar text in another section.)
>
>
>----------------------------------------------------------------------
>COMMENT:
>----------------------------------------------------------------------
>
>Several TLVs have "Reserved" fields, yet you never explain what "Reserved"
>means. You do explain what reserved flags mean in some of them. I suggest
>either explicitly explaining what Reserved means in each case or specify
>this
>in the terminology section near the beginning of the document.
>
>The document never specifies byte order for length fields.
>
>The acronym NSSA is never explained and it has no reference.
>
>