[secdir] Secdir last call review of draft-ietf-isis-reverse-metric-13

Barry Leiba <barryleiba@computer.org> Thu, 04 October 2018 17:36 UTC

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From: Barry Leiba <barryleiba@computer.org>
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Date: Thu, 04 Oct 2018 10:36:59 -0700
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Subject: [secdir] Secdir last call review of draft-ietf-isis-reverse-metric-13
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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.