Subject: [tsvwg] NQB draft - comments from David B

From: "Black, David" <[email-masked]>
Date: Sun, 15 Sep 2019 23:11:42 +0000

Some short comments on a few topics as an individual - all of these are IMHO.  Sorry for the delayed silence - I got laid out for several days by a kidney stone starting on Sep 4, and catching up has taken a while.

-- [1] Traffic Protection (e.g., Queue Protection) and the NQB PHB.

If Traffic Protection/Queue Protection is completely optional for the NQB PHB, would someone please explain how this PHB differs from EF and VOICE-ADMIT?  In particular (at the least as a straw proposition for demolition purposes) - Should the NQB draft be re-focused on why non-queue-building flows are good fits to those PHBs and how to effectively use traffic protection (e.g., queue protection) with those PHBs??

FWIW, my take on the discussion so far is that the "no incentives to misuse" claim lacks credibility, making "MUST implement traffic protection" an appropriate place to start from to proceed to specify exceptions.  The walled-garden/app-store example might be one such exception, although that appears to assume perfect curation of the app store, a proposition for which there are plenty of counterexamples.

-- [2] Priority Queuing or the lack thereof.

If NQB PHB traffic is never supposed to be subject to priority queuing, then 0x2A sure looks like the wrong default DSCP to recommend (IMHO).

-- [3] RFC 2119 hair-splitting.

> To prove MUST is necessary, you have to prove protection is necessary in every scenario.

That's definitely wrong for "MUST implement" and likely wrong for "MUST use."   The "MUST implement" view is not just my opinion - this is how the Security Area views implementation requirements for security mechanisms - "MUST implement" ensures that the mechanisms are available if the operator should discover that she needs them.  As we appear to be dealing with potential for  theft and denial of service attacks, we should expect to have to answer to the Security Area on this topic.

With regards to "in every scenario," I would suggest listing the interesting/important scenarios that are exceptions to "MUST implement" with cogent explanations of why they are exceptions.

Thanks, --David
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David L. Black, Senior Distinguished Engineer
Dell EMC, 176 South St., Hopkinton, MA  01748
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