Re: [Last-Call] Last Call SECDIR Review of draft-ietf-lisp-6834bis-11

[Donald Eastlake <d3e3e3@xxxxxxxxx>]

Hi Luigi,

Thanks for all the changes. It looks acceptable to me now.

Thanks,
Donald
===============================
 Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
 2386 Panoramic Circle, Apopka, FL 32703 USA
 d3e3e3@xxxxxxxxx

On Thu, Jun 2, 2022 at 8:29 AM Luigi Iannone <ggx@xxxxxxxxx> wrote:

Thanks Donald

Revision -13 includes the text suggested by Alvaro and the fix in section A.3

Ciao

L.

On 2 Jun 2022, at 04:49, Donald Eastlake <d3e3e3@xxxxxxxxx> wrote:

Hi Luigi,

I think -12 is pretty good. The change suggested by Alvaro should be included. And I think the last sentence in Section A.3 in -12 should probably be a separate paragraph and the start should be "Note that ..." rather than "To be noted that ...". With those changes, I am OK with the draft.

Thanks,
Donald
===============================
 Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
 2386 Panoramic Circle, Apopka, FL 32703 USA
 d3e3e3@xxxxxxxxx

On Wed, Jun 1, 2022 at 8:16 AM Luigi Iannone <ggx@xxxxxxxxx> wrote:

Hi Donald,

A new revision of the drafts has been submitted.

Here is the link to the rfcdiff: https://www.ietf.org/rfcdiff?url2=draft-ietf-lisp-6834bis-12.txt

Let  me know if this revision does not address your concerns.

Thanks

Ciao

L.

On 1 Jun 2022, at 10:45, Luigi Iannone <ggx@xxxxxxxxx> wrote:

On 1 Jun 2022, at 05:29, Donald Eastlake <d3e3e3@xxxxxxxxx> wrote:

See below at <de>

On Mon, May 30, 2022 at 9:32 AM Luigi Iannone <ggx@xxxxxxxxx> wrote:

Hi Donald,

Thank you very much for your review.

I take this last updated review and provide some answers inline.

On 30 May 2022, at 04:35, Donald Eastlake <d3e3e3@xxxxxxxxx> wrote:

I have updated my review of the -10 version for -11 below.
Comments/suggestions that I do not comment on still apply.

On Wed, May 25, 2022 at 3:41 PM Donald Eastlake <d3e3e3@xxxxxxxxx> wrote:

I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG.  Document editors and WG chairs should treat these comments just like any other last call comments. Sorry this is a bit late.

The summary of the review is Ready with Issues.

Well, minor issues...

...

SECURITY

This draft appears to completely ignore the issue of Map Version Number advancing so far so quickly that an old version number is encountered that appears to be newer than or equal to the current version number. Why can't this happen? Or if it can, why doesn't that hurt?

This is more of an operational point. If you update a mapping, the best would be to give sufficient time so that everybody updates and there is no such a risk.

What about adding in section 7 “dealing with Map-Version Numbers” the following sentence.

It is an operational question to make sure that Map-Version numbers are not updated so frequently as to create the risk that very old version numbers appear newer (because of the circular space). 

Would that address your issue?    

 

<de> Not really. (1) I think the document needs to say what happens if the numbers wrap around and overlap. (2) Assuming the answer to 1 is as bad as I think, then it is not "an operational question" to avoid this but rather "an operational requirement".  That is, there should be a statement something like "Map Version Number incrementing and TTL MUST be managed so that an old Version Numbers will not be confused as a new Version Number.

This last sentence is great. I will put it in section 7.

Section 8, last paragraph: Says Map-Versioning can only be used in trusted, closed environments but Section 7.1 and 7.2 seem to talk about what to do about the Map-Version field without any reference to this, but mentioning private deployments for certain error conditions. For example, Section 7.2 point 3 says to discard a packet on an erroneous Map-Version value except perhaps in some private deployments. But if you MUST NOT use Map-Versioning on the open internet, shouldn't it be required to discard all LISP encapsulated packets with Map-Version numbering if received over the public Internet?

Actually section 7.1 reads:

Operators can configure exceptions to this
       recommendation, which are outside the scope of this document.

We should have done the same for 7.2, will do in a revision.

<de> Well, adding that to Section 7.2 would help. But the problem is the following sentence in Section 8:

   Map-Versioning MUST NOT be used over the public Internet and SHOULD
   only be used in trusted and closed deployments.

It seems to me that sentence says you can only use Map-Versioning in a private network and that private network SHOULD be trusted. So I guess it allows use in an untrusted private network... Is that what you want to say?

This is similar to the comment made by Paul.

His suggestion is to change the SHOULD in a MUST. Would this work for you as well?

 

Otherwise, the Security Considerations seem adequate although I think the 1st and 2nd paragraphs of Section 8 should be swapped.

Yes, it may read better. Will be swapped in the next revision.

OTHER ISSUES

Section 6, right after equation 3: Isn't "(69 + 4096) mod 4096" the same as "69"? And isn't 69 equal to 69, not less than 69? Shouldn't it say "Map-Version numbers in the range [69 + 2049; 68] are smaller than 69"? Or actually "in the ranges [69 + 2049; 4095] and [1;68] are smaller than 69"?

Wonderful catch. Should be 

[69 +  2049; (69 + 4095) mod 4096]

Will fix.

Section A.3: How is it possible to tell that no more traffic will be received? Should this instead be something like wait the TTL of the mappings to that RLOC plus estimated transit time and some margin for safety?

Absolutely right, the sentence should be:

   Upon updating the mapping, the RLOC will receive the less and less 

   traffic because remote LISP sites will get the updated mapping. 

   At least one TTL after the mapping was updated, it could be 

   considered safe to shut down the RLOC gracefully, because all 

   sites actively using the mapping should have updated

   it. 

Sounds better?

<de> Yes, that's better. But I would suggest alternate wording such as the following:

     "Upon updating the mapping, the RLOC will receive less and less 

   traffic because remote LISP sites will request the updated

   mapping and see that it is disabled. At least one TTL, plus a

   little time for traffic transit, after the mapping is updated,

   it should be safe to shut down the RLOC gracefully, because

   all sites actively using the mapping should have been updated."

Thanks a lot, it reads much better. 

TYPOS/MINOR

Should the document say anything about mapping changes possibly causing re-ordering?

Not sure what do you mean by “re-ordering”, can you articulate?

<de> I was thinking about adding one sentence somewhere something like the following: 

"A change in map version resulting in a change in ETR for a flow can result in the re-ordering of the packet in the flow just as any other routing change could cause re-ordering."

Yes, that is again absolutely correct. I will add the sentence.

Section 1: I think the following should end with "ITR": "If this is not the case, the ETR can directly send a Map-Request containing the updated mapping to the ETR,"

Above fixed in -11.

Section 7.2, first sentence just after point 3: Suggest using "MAY" in "may be more restrictive."

Will be changed in the next revision.

Section A.2.3: "provider edge" pops up here with no other mention or explanation anywhere in the draft.

Either drop the term or provide some sort of definition/explanation.

Provider edge should actually be just “domain"

<de> OK. 

Section A.2.3: The last two sentences sound like they contradict each other. I assume the last sentence is refering to change in the Source mapping. Suggest "the mapping" -> "the Source mapping".

Yes, is

With this setup, the Proxy-ETR, by looking at the Source Map-Version Number, 

is able to check whether the mapping has changed.

<de> OK. 

EDITORIAL

Section 1: "This operation is two-fold." -> "This information has two uses."

New Section 6: "... MUST consist in an increment ..." -> "... MUST
consist of an increment ..."

New Section A.2.3: "uRPF" is used only once so the acronym should be
dropped and only the expansion used.

Will update as suggested in the next revision.

<de> OK.

Thanks again for the feedback.

Ciao

L.

<de> Thanks,

Donald
===============================
 Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
 2386 Panoramic Circle, Apopka, FL 32703 USA
 d3e3e3@xxxxxxxxx

Thanks again for the review.

Let me know if the proposed changes address your comments.

Ciao

L.

Thanks,
Donald
===============================
Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
2386 Panoramic Circle, Apopka, FL 32703 USA
d3e3e3@xxxxxxxxx

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