Re: [Detnet] Roman Danyliw's Discuss on draft-ietf-detnet-mpls-oam-14: (with DISCUSS and COMMENT)

[Greg Mirsky <[e-mail]>]

Hi Roman,
thank you for your questions and comments. Please find my notes below
tagged by GIM>>.

Regards,
Greg

On Wed, Jan 3, 2024 at 7:03 AM Roman Danyliw via Datatracker <
[e-mail]> wrote:

> Roman Danyliw has entered the following ballot position for
> draft-ietf-detnet-mpls-oam-14: Discuss
>
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> for more information about how to handle DISCUSS and COMMENT positions.
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>
>
> ----------------------------------------------------------------------
> DISCUSS:
> ----------------------------------------------------------------------
>
> ** Section 3.1
>
>       Level - is a 3-bit field.  The Level field is used to cope with
>       the "all active path forwarding" characteristics of the PREOF
>       concept.  A hierarchical relationship between OAM domains can be
>       created using the Level field value.
>
> How are level values constructed in an interoperable way?  How does one
> know
> where a value fits in a hierarchy?
>
GIM>> Thank you for pointing this out to me. The Level field is analogous
to the Maintenance Domain (MD) Level used in ETH-OAM and discussed in
Section 18.3 IEEE Std.802.1Q-2014. Figure 18.7 is very helpful in
illustrating the relationships among different MD Levels. Would the updated
text address your concern:
NEW TEXT:
      Level - is a 3-bit field.  Semantically, the Level field is
      anlogous to the Maintenance Domain Level in [IEEE.802.1Q].  The
      Level field is used to cope with the "all active path forwarding"
      characteristics of the PREOF concept.  A hierarchical relationship
      between OAM domains can be created using the Level field value,
      illustrated by Figure 18.7 in [IEEE.802.1Q].

>
>
> ----------------------------------------------------------------------
> COMMENT:
> ----------------------------------------------------------------------
>
> Thank you to Hilarie Orman for the SECDIR review.
>
> I support the DISCUSS position of Martin Duke.
>
> ** Section 3.1.
>       Sequence Number - is an unsigned circular 8-bit field.  The
>       sequence number space is circular with no restriction on the
>       initial value.
>
> -- is an “unsigned circular … field” an unsigned integer that wraps around?
>
GIM>> Correct.

>
> -- how is wrap-around handled?
>
GIM>> The sequencing of packets in DetNet is used by Packet Elimination and
Packet Ordering Functions on the DetNet service sub-layer. The former
eliminates replicated copies of the earlier forwarded packet. The latter
improves in-order delivery within a given DetNet flow.

>
> ** Per the SECDIR review noting these OAM headers could enable tracking or
> fingerprinting, it would be valuable to make a statement to that effect in
> the
> Security Considerations.
>
GIM>> Thank you for your kind reminder about that suggestion. In this
draft, we missed noting that the Security Considerations discussed in
draft-ietf-detnet-oam-requirements are inherited. If we do that (see
below), would it be sufficient considering the following text in the DetNet
OAM Requirements:
   Furthermore, the analysis of OAM security concerns in
   Section 6 of [RFC7276] also applies to DetNet OAM, including the use
   of OAM for network reconnaissance.

NEW TEXT:
6.  Security Considerations

   Security considerations discussed in DetNet specifications [RFC8655],
   [RFC9055], [RFC8964], and [I-D.ietf-detnet-oam-framework] are
   applicable to this document.  Security concerns and issues related to
   MPLS OAM tools like LSP Ping [RFC8029], and BFD over PW [RFC5885] also
   apply to this specification.