Subject: Secdir last call review of draft-ietf-isis-reverse-metric-13

From: Barry Leiba <[email-masked]>
Date: Thu, 04 Oct 2018 10:36:59 -0700

Reviewer: Barry Leiba
Review result: Ready

This document is well written and seems ready to go.  The only security issue I
thought of as I read through it (attacking by spoofing a reverse metric) is
covered in the Security Considerations section.

I found one sentence to be slightly ambiguous, but only very slightly.  In
Section 3.5:

   A router MUST advertise a Reverse Metric TLV toward a neighbor only
   for the operational maintenance window period during which it wants a
   neighbor to temporarily update its IS-IS metric or Traffic
   Engineering parameters towards it.

It begins to look like it's saying that a router MUST advertise this under
certain conditions, and it took me a moment to get that it's actually
*limiting* when it should be advertised (the "MUST" applies to the "only"
clause).  If you think my suggested replacement reads well, you might use it;
if not, no problem:

   A router MUST limit the period during which it advertises a Reverse Metric
   TLV toward a neighbor only to the operational maintenance window period
   during which it wants that neighbor to temporarily update its IS-IS metric
   or Traffic Engineering parameters towards it.

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From: Tony Przygienda <[email-masked]>
Date: Thu, 4 Oct 2018 10:42:35 -0700

funny enough,
https://tools.ietf.org/html/draft-shen-isis-spine-leaf-ext-06#page-12 by
the overlaping author set seems already to circumvent this ;-)

On Thu, Oct 4, 2018 at 10:37 AM Barry Leiba <[email-masked]> wrote:

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From: "Naiming Shen (naiming)" <[email-masked]>
Date: Fri, 5 Oct 2018 04:33:17 +0000

Hi Barry,

Thanks for the review and your suggestion makes sense. The original wording
is confusing. Also, as Tony has pointed out in the same thread, this sentence
was the original intention when start of the draft, but it has been extended for
other use cases described in section 1. How about this on top of your suggestions:

   For the use case in section 1.1, Node and Link Isolation, a router MUST limit
   the period during which it advertises a Reverse Metric TLV toward a neighbor
   only to the operational maintenance window period during which it wants that
   neighbor to temporarily update its IS-IS metric or Traffic Engineering parameters
   towards it.

Best Regards,
- Naiming

> On Oct 4, 2018, at 10:36 AM, Barry Leiba <[email-masked]> wrote:
> 
> Reviewer: Barry Leiba
> Review result: Ready
>

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From: Barry Leiba <[email-masked]>
Date: Fri, 5 Oct 2018 00:36:35 -0400

Perfect; thanks.

Barry

On Fri, Oct 5, 2018 at 12:33 AM Naiming Shen (naiming) <[email-masked]>
wrote:

> --
Barry
--
Barry Leiba  ([email-masked])
http://internetmessagingtechnology.org/