Re: [BEHAVE] (no subject)

Simon Perreault <simon.perreault@viagenie.ca> Thu, 27 June 2013 13:55 UTC

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Date: Thu, 27 Jun 2013 15:55:24 +0200
From: Simon Perreault <simon.perreault@viagenie.ca>
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Subject: Re: [BEHAVE] (no subject)
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Le 2013-06-27 15:44, ivan c a écrit :
>> I still haven't seen any explanation why the following excerpts do not
>> apply.
>>
>> RFC 4787:
>>
>>      REQ-3:  A NAT MUST NOT have a "Port assignment" behavior of "Port
>>         overloading".
>>
>> RFC 5382:
>>
>>      REQ-7:  A NAT MUST NOT have a "Port assignment" behavior of "Port
>>         overloading" for TCP.
>
> Because some NATs would like to do port overloading, which is in
> contradiction with these requirements.

"Would like to" is not a valid reason. We need technical arguments.

> See section 4. of
> http://tools.ietf.org/html/draft-ietf-behave-requirements-update-00 .
> You're mentioned as an author on this draft by the way.

I'm not disagreeing with myself. I am only observing that this 
discussion still has not yielded any good technical argument that we 
could add to our draft.

I have suggested that one condition where port overloading could be used 
is when the NAT knows that it will not disrupt the application protocol. 
For example, the protocols running on TCP port 80 and UDP port 53 (HTTP 
and DNS) are purely client-server and therefore would not be affected by 
port overloading. Allowing NATs to do port overloading for those ports 
only would probably solve the scalability problem since they account for 
a large portion of the traffic.

Do we really need anything more complex?

> In this post I explain why port overloading can be somewhat desirable:
> http://www.ietf.org/mail-archive/web/behave/current/msg10896.html
> I make the same point across a large number of my posts.

We know that port overloading is desirable for a number of reasons.

What we need to argue is why the undesirable effects of port overloading 
do not apply or can be ignored.

Simon