Hi Rémi,

Thank you for the comments.

Please see inline.

Cheers,
Med 

-----Message d'origine-----
De : Rémi Després [mailto:[email protected]] 
Envoyé : lundi 9 mai 2011 11:10
À : Satoru Matsushima; BOUCADAIR Mohamed OLNC/NAD/TIP; Yiu Lee; Olaf Bonness; 
Isabel Borges
Cc : Softwires-wg
Objet : Re: [Softwires] Motivation draft for stateless v4 over v6 solution

Satoru-san, Med, all authors,

Congratulation for this important I-D, and for the quick convergence among all 
of you. 

Here are, after a detailed review, some remarks:

1. Sec 2 - Terminology (and some other instances of "port range")

"Port space", as used in sec. 5.3, or "port set", would be more appropriate 
than "port range" in a motivation document because:
- A port range is a particular case of port set or port space, but not the 
reverse.
- At least one documented solution uses port sets that contain several port 
ranges.

Med: I don't see much the difference between a port range and a port set. IMO, 
what is important is to use consistent terminology in the document. Do you have 
any pointer (other that the solution document you are referring to) where "port 
set" is defined? If needed, I can update the text to state that both "port 
range" and "port set" are used interchangeably.


2. Sec 3. IPv4 Service Use case

While the "Host based model is out of scope", it would be IMHO good to note 
that:
"The model can however apply to any host that includes a CPE function".

Med: I prefer having the explicit statement to say the host-based model is out 
of scope.


5.1. Dependency Between IPv4 and IPv6 Address Assignments

The I-D says "Providing two IPv6 prefixes avoids the complexity related to the 
adaptation of the IPv6 addressing scheme to the IPv4 addressing scheme".
But some solutions don't require to adapt the IPv6 addressing scheme to that of 
IPv4.
(A particular example is described in sec 3.2 of draft-despres-softwire-sam-01. 
With it, several IPv4 prefixes are supported without any impact on the IPv6 
addressing scheme)
Suggestion: after "complexity", add "that may be".

Med: Done. FWIW, I also updated that section with a comment received from R. 
Maglione:

"For Service Providers requiring to apply specific policies on per 
Address-Family (e.g., IPv4, IPv6), some provisioning tools (e.g., DHCPv6 
option) may be required to derive in a deterministic way the IPv6 address to be 
used for the IPv4 traffic based on the IPv6 prefix delegated to the home 
network. "


5.3. Port Randomization

The I-D says "Other means than the (IPv4) source port randomization to provide 
protection against attacks should be used (e.g., use
[I-D.vixie-dnsext-dns0x20] to protect against DNS attacks, [RFC5961] to improve 
the robustness of TCP against Blind In-Window Attacks)".

However:
- The solution cited as example is from an expired  I-D.
- Another solution is that the DNS server of the operator be accessible in 
IPv6, and that the CPE translates IPv4 DNS queries to send them to this server. 
In this case, no port-set restriction applies.
Suggestion: 
- Delete the paragraph, or,
- Note that IPv6 DNS servers is a solution (and avoid the reference to 
I-D.vixie-dnsext-dns0x20).

Med: I updated the text to mention that using IPv6 is one of the solutions.


I think this I-D should become asap a WG draft.
(This would preferably be with some improvements like those proposed above, but 
this isn't IMHO a prerequisite.)

The sooner it reaches RFC status, the better. 

Regards,
RD






Le 6 mai 2011 à 12:39, Satoru Matsushima a écrit :

> Dear colleague, 
> 
> We've uploaded an I-D to express our motivation of stateless IPv4 over IPv6 
> as an IPv6 transition solution. Since the outcome of recharter session in 
> last softwires wg meeting, ADs required the motivation draft to standardize 
> stateless v4 over v6 solution at IETF.
> 
> We, authors of the draft, have been trying to clearly explain our motivation, 
> scope, and current open questions for stateless solution as much as possible 
> in this draft. We believe that it should be helpful to understand what our 
> motivation is.
> 
> Please find it out from following url:
> http://www.ietf.org/id/draft-operators-softwire-stateless-4v6-motivation-00.txt
> 
> We'd like to have your kind review, and comments, also welcome to discuss 
> about the motivation in the softwires mailing list.
> 
> Best regards,
> --satoru
> _______________________________________________
> Softwires mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/softwires


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