Subject: [tcpm] Comments on draft-ietf-tcpm-ao-test-vectors

From: "Scharf, Michael" <[email-masked]>
Date: Mon, 11 Oct 2021 22:10:21 +0000

Joe, Juhamatti,

I have read draft-ietf-tcpm-ao-test-vectors-01. I find this document useful. I 
cannot validate the actual test vectors, but I have some (minor) editorial 
remarks:

* Abstract:  "The vectors also validate both whole TCP segments as well as 
segments whose options are excluded for NAT traversal."

I find the term "NAT traversal" confusing in this context. As outlined in 
Section 9.2 of RFC 5925, "TCP-AO cannot interoperate natively across NAT/NAPT 
(Network Address Port Translation) devices, which modify the IP addresses 
and/or port numbers." The term "middlebox" used in Section 9.1 of RFC 5925 may 
be a better choice.

* Introduction: "This document provides test vectors from an implementation 
that has been validated against another routing vendor for interoperability.."

IMHO a better wording instead of "another routing vendor" would be "another 
implementation" or the like.

Nit: ".." at the end oft he sentence.

* Section 3.1: "The terms 'active' and 'passive' are used as defined for TCP 
[RFC793]."

I think TCPM could (and should) start using 793bis as reference for TCP in 
documents finished after 793bis, as far as possible. Why do we not eat our own 
dogfood?

* Section 3.1.1 and elsewhere

The document uses inconsistent spelling of hex numbers. In section 3.1.1 
capital letters are used, unlike the later examples. I don't understand why. 
Also, maybe it could make sense to better emphasise that some values are 
decimal, while others are hex or binary. In most cases it is relatively clear 
from the context, but in section 3.1.1 one actually has to look at the numbers 
to understand the encoding.

Best regards

Michael
(with chair hat off)

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From: "[email-masked]" <[email-masked]>
Date: Mon, 11 Oct 2021 15:15:19 -0700

Hi, Michael,

Thanks for the comments - some responses below...
—
Joe Touch, temporal epistemologist
www.strayalpha.com

> On Oct 11, 2021, at 3:10 PM, Scharf, Michael <[email-masked]> wrote:
> 
> Joe, Juhamatti,
> 

It should cite rfc6978 for the latter, and NAT is the term used there because this isn’t a generic middlebox issue.

> implementation" or the like.

Agreed.

> Nit: ".." at the end oft he sentence.

Yup. Will fix.

> documents finished after 793bis, as far as possible. Why do we not eat our own 

We don’t necessarily want to hold this doc for that update (if it gets held up). So we’ll take this as it goes (presumably ID nits will complain at some point when the other RFC is published).

> capital letters are used, unlike the later examples. I don't understand why. 

I’ll fix that.

> to understand the encoding.

Agreed.

> Best regards
> 
> Michael
> (with chair hat off)
> _______________________________________________
> tcpm mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/tcpm

---

From: "[email-masked]" <[email-masked]>
Date: Mon, 11 Oct 2021 20:38:29 -0700

—

> On Oct 11, 2021, at 3:15 PM, [email-masked] wrote:
> 

Correction: there are two different features and they are ambiguously indicated.

The abstract should refer to middle box traversal (removing TCP options from coverage); the intro later describes NAT traversal, which omits the port numbers. The two are distinct and this has been clarified in the new text.

Joe

---

From: "Scharf, Michael" <[email-masked]>
Date: Tue, 12 Oct 2021 07:56:20 +0000

Yep, the ambiguous wording in the abstract triggered my comment. Both mechanisms should be explained separately.

Thanks

Michael

From: [email-masked] <[email-masked]>
Sent: Tuesday, October 12, 2021 5:38 AM
To: Scharf, Michael <[email-masked]>
Cc: [email-masked]; [email-masked]
Subject: Re: [tcpm] Comments on draft-ietf-tcpm-ao-test-vectors

—
Joe Touch, temporal epistemologist
www.strayalpha.com<http://www.strayalpha.com>

On Oct 11, 2021, at 3:15 PM, [email-masked]<mailto:[email-masked]> wrote:

Joe