Subject: [Gen-art] Gen-ART Last Call review of draft-ietf-ccamp-rsvp-te-bandwidth-availability-13

From: Paul Kyzivat <[email-masked]>
Date: Wed, 23 Jan 2019 13:28:41 -0500

I am the assigned Gen-ART reviewer for this draft. The General Area 
Review Team (Gen-ART) reviews all IETF documents being processed by the 
IESG for the IETF Chair. Please treat these comments just like any other 
last call comments. For more information, please see the FAQ at 
<​http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.

Document: draft-ietf-ccamp-rsvp-te-bandwidth-availability-13
Reviewer: Paul Kyzivat
Review Date: 2019-01-23
IETF LC End Date: 2019-01-31
IESG Telechat date: ?

Summary:

This draft is on the right track but has open issues, described in the 
review.

Issues:

Major: 0
Minor: 1
Nits:  1

1) NIT:

Section 3.1 includes the following:

    ... The Ethernet SENDER_TSPEC object
    MAY include more than one Availability TLV. The Availability TLV has
    the following format:

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Index      |                 Reserved                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                          Availability                         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

I find it confusing that this is described as a TLV yet it shows neither 
a type nor a length. Apparently it is only showing the value portion of 
the TLV. The type portion is only mentioned in the IANA considerations 
section, and isn't explicitly linked to this element. I would expect 
this to be shown something like:

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Type=4                     | Length=96                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Index      |                 Reserved                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                          Availability                         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

(But the type value needs to be keyed to the IANA assigned value, since 
there is no guarantee that IANA will assign 4 for this.)

2) MINOR:

Section 3.2 includes the following:

    When a node does not support the Availability TLV, it SHOULD
    generate PathErr message with the error code "Extended Class-Type
    Error" and the error value "Class-Type mismatch" (see [RFC2205]).

I have a question about this: Is this the default behavior that is 
prescribed for any unknown TLV type found in an Ethernet SENDER_TSPEC 
object, or is this behavior specific to the "availability" TLV? It is a 
problem if this is not the default behavior.

And is there a reason for SHOULD (rather than MUST) here? If so, please 
describe the situations where this need not be done.

---

From: "Yemin (Amy)" <[email-masked]>
Date: Thu, 24 Jan 2019 16:00:36 +0000

Hi Paul, 

Thanks for the comments. 
Regarding nits: we followed the usual way, just show the value field. But I don't mind to make a complete figure. 
Minor issue: you're quiet right. It should be a MUST here.  
We will address these comments in next version. Thanks again. 

BR,
Amy
________________________________________
发件人: Paul Kyzivat [[email-masked]]
发送时间: 2019年1月24日 2:28
收件人: [email-masked]
抄送: General Area Review Team
主题: Gen-ART Last Call review of draft-ietf-ccamp-rsvp-te-bandwidth-availability-13

Summary:

Issues:

Major: 0
Minor: 1
Nits:  1

1) NIT:

        0                   1                   2                   3

        0                   1                   2                   3

2) MINOR:

---

From: Paul Kyzivat <[email-masked]>
Date: Thu, 24 Jan 2019 15:38:18 -0500

Amy,

> Regarding nits: we followed the usual way, just show the value field. But I don't mind to make a complete figure.

In most places that define TLVs I see the type and length included in 
the figure. If the documents related to yours don't do that, and you 
want to follow that style, then please at least indicate in the text 
that you are only showing the value part, and explicitly call out the 
type and length.

You didn't mention my question:

> I have a question about this: Is this the default behavior that is prescribed for any unknown TLV type
> found in an Ethernet SENDER_TSPEC object, or is this behavior specific to the "availability" TLV?

You can't mandate new behavior for things that don't implement this 
specification. If this is already the mandated behavior for an unknown 
TLV type then you technically don't need to say anything. If you want 
to, then best to reference the place that mandated this behavior. (I 
didn't find it in RFC2205.) And you could quote what that behavior is, 
or paraphrase it in a non-normative way.

	Thanks,
	Paul