[tsvwg] draft-ietf-tsvwg-ecn-tunnel-04 - Editorial comments.

[Gorry Fairhurst <gorry at erg.abdn.ac.uk>]

In addition, I have a few minor comments on rev -04 below:

---
Abstract:
- I found the sentence that starts below to be a little hard to read, 
rephrasing would be helpful:
"The new rules propagate the ECN field whether..."
---
Abstract:
- There seems some recommendations buried in section 7, if these are 
useful they may benefit from a mention in the abstract, such as:

"RFC 4774 permits the Diffserv codepoint (DSCP) [RFC2474] to
'switch in' alternative behaviours for marking the ECN field and 
requires new methods to consider the implications of tunnel encapsulated 
packets. Section 7 of this document extends the considerations in 
section 5.4 of RFC 4774."
<see comments email for discussion on Section 7>
---
Section 3:
- Typo, :
"inAppendix A"
   ^
---
Section 4:
NiT:
"If absolutely necessary..."
    ^^^^^^^^^^
- Perhaps it is strong enough to say "necessary"? or to move the NOT 
RECOMMENDED to the start of the paragraph to emphasise this.
---
Section 5.1:
- This section makes a claim that some codepoint..
"has never been used on the Internet"
- Rather than face a pedantic correction with a corner case, it may be 
safer just to say "is not known to have been used"...
- The same comment applies to 5.2.
---
Section 5.1:
"However, this is such a remote possibility that in general.. are NOT 
REQUIRED to implement."
- The in "in general" part worries me. I think this should be expressed 
more clearly, since it contains some RFC 2119 keywords.
---
Section 5.3.2:
- This section reads better, but still repeats a little the covert 
channel theme.
---
Section 7:
- separate email.
---
Section 10:
- Para starting:
"The new rules...
- I think the last sentence would read better without a "But" at the start.
---
Section 12:
- This section could be removed as we move to a WGLC, or marked for 
later RFC-Ed removal.
---
Appendix B.1:
- Para starting:
"ECN at the IP layer..."
This para finishes with:
"Therefore the goals of IPsec and ECN are incompatible."
- I don't mind if this stays as it is written, but it does sound a kind 
of philosophical view, and seems odd to me.
---
Appendix D:
- I wonder if thus Appendix could be more concise? (e.g. it does repeat 
the covert channel case). Given this is now standards-action can we 
compact some of this?
---
Appendix E:
- This appendix was usefult to dervive the Spec. It now appears to 
repeat what is now said earlier, and I suspect much of this text is not 
needed here and would already be covered in 
[I-D.ietf-pcn-marking-behaviour] - which I now think is also scheduled 
for publication by PCN.
---