Re: [Lsr] Secdir last call review of draft-ietf-isis-segment-routing-msd-16

"Les Ginsberg (ginsberg)" <> Wed, 26 September 2018 20:45 UTC

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From: "Les Ginsberg (ginsberg)" <>
To: David Waltermire <>, "" <>
CC: "" <>, "" <>, "" <>
Thread-Topic: Secdir last call review of draft-ietf-isis-segment-routing-msd-16
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Date: Wed, 26 Sep 2018 20:45:03 +0000
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Subject: Re: [Lsr] Secdir last call review of draft-ietf-isis-segment-routing-msd-16
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David -

Thanx for the review.
A new version of the draft (17) has been published to address your comments - subject to my responses below.

> -----Original Message-----
> From: David Waltermire <>
> Sent: Tuesday, September 25, 2018 12:14 PM
> To:
> Cc:;; draft-ietf-isis-segment-routing-
> Subject: Secdir last call review of draft-ietf-isis-segment-routing-msd-16
> Reviewer: David Waltermire
> Review result: Has Issues
> I have reviewed this document as part of the security directorate's ongoing
> effort to review all IETF documents being processed by the IESG.  These
> comments were written primarily for the benefit of the security area
> directors.
>  Document editors and WG chairs should treat these comments just like any
> other last call comments.
> The summary of the review is Ready with (minor) issues
> My apologies for the late review on this draft. Overall I found this document
> to be well-written, and concise.
> General Comments:
> This document uses a mix of case around RFC2119 language (e.g., MAY may).
> You should use text from RFC8174 to indicate that lowercase versions of the
> keywords are not normative, or adjust the case of the lowercase words to
> ensure there is no confusion.
[Les:] Section 1.2 does include the standard boilerplate for RFC 2119/RFC8174.

I checked all the lower case uses of "may" and they are intentional.
There was one instance of "should" that I changed to uppercase.

> Minor nit: There is some inconsistency in the use of "MSD-Type" (the value)
> and "MSD type" (the concept). Suggest cleaning this up.
[Les:] Done

> Specific comments:
> Section 1:
> Para 1: s/to insure/to ensure/

[Les:] Done.

> Section 4:
> The last paragraph establishes a requirement on the registration of an MSD
> Type to define what the absence of a given MSD Type means. This is an
> important requirement that must be addressed during registration of new
> MSD Types. IMHO, this requirement should be echoed in the registration
> information in section 6 to make sure it is not overlooked.
[Les:] I disagree. Section 6 is defining exactly what should go into the new IANA registry.
The definition of "absence" is something that will have to be provided in the documents which define new MSD-types, but that will NOT be captured in the registry so including this in Section 6 isn’t appropriate.

> Section 6:
> The "Base MPLS Imposition MSD" should reference section 5 of this
> document.

[Les:] Again - Section 6 is defining what will go into the registry. The registry will reference the document - not a specific section of the document.

> The registration for "Experimental" should be marked as "Reserved for
> Experimental Use" or just "Experimental Use" to align with RFC8126. RFC8126
> states that "it is not appropriate for documents to select explicit values from
> registries or ranges with this policy". It might be good to add a note alongside
> the one on "Designated Experts" indicating that values from this range are
> not assignable.
[Les:] I have changed the text to "Experimental Use".
I think the rest of your comment is addressed by RFC 8126 - which is referenced.

> The "Interior Gateway Protocol (IGP) Parameters" registry has the
> "Standards Action" policy assigned. The new "IGP MSD Types" sub-registry
> does not have the "Standards Action" policy. Was this intentional? If so, this
> should be explained. This is also confusing since the guidance for expert
> reviewers in
> RFC7370 implies that registrations are based on the "RFC Required" or
> "Standards Action" policies.
[Les:] IS-IS registries are typically Expert Review. This derives from considerations related to the liason with ISO JTC 1/SC6 (RFC 3563).
OSPF registries are typically Standards Action.

As IGP Parameters was defined by draft-ietf-ospf-segment-routing-extensions, it is Standards Action.
But as MSD-Types is being defined in an IS-IS draft...

Please learn to live with this.
It isn’t a significant issue in my view.

> Section 7:
> The security considerations in RFC7981 ask that security considerations
> around the disclosure and modification of this type of information is
> described in extensions. This has been done, but RFC7981 also asks that an
> integrity mechanism be provided if there is a high risk resulting from
> modification of capability information. There is no discussion in the
> document's security consideration about the nature of risk in this case and
> why an integrity mechanism is not needed. It seems like false information
> can be used to cause a denial of service regarding computed paths. This
> sounds like having this happen could be bad. I am not an expert on routing
> protocols, so I am not sure if this is an issue. How bad and likely is such a risk?

[Les:] The integrity mechanism is (as you point out) discussed in the Security section of RFC 7981 - which is referenced in the Security Section of this document.
The introduction of a new TLV does not alter the integrity mechanism requirements.