FYI

-------- Message original --------
Sujet : Re: [BEHAVE] FYI: draft-despres-sam-02 enclosed
Date : Tue, 17 Mar 2009 09:39:13 +0100
De : Rémi Després <[email protected]>
Pour : Margaret Wasserman <[email protected]>
Copie à : Internet Area <[email protected]>, Softwires WG <[email protected]>, Behave WG <[email protected]>
Références : <[email protected]> <[email protected]>


Margaret Wasserman  -  le (m/j/a) 3/17/09 1:13 AM:
>
> Hi Remi,
>
> I have a few high-level comments/questions on this draft from my first 
> reading, and I may have more after I have reviewed it in more detail.
>
> (1) You have indicated that you would like to discuss this draft in 
> the 6AI BOF, but you have not cc:ed the mailing list for the 6AI BOF 
> ([email protected]).  Also, have you talked to the chairs of the 6AI BOF 
> (Bob Hinden and Dan Wing) about whether they are willing to include 
> this draft on the agenda, despite the fact that it has not been posted 
> to the I-D archive?  There doesn't appear to be an agenda online for 
> the 6AI BOF yet, so I am not sure if it will be included.
I started with the NAT66 mailing list, and only followed with WG lists.
See also Dan's answer.
>
> (2) The end hosts in the SAM system need to know their globally 
> routable addresses, so how can SAM be said to provide address 
> independence?
Routing within the site is based on local addresses, e.g. ULAs.
That's only in SAM-capable CPEs and in SAM-capable hosts that, knowing 
SAM parameters, global-address packets can be encapsulated in 
local-address packets.
> (3) Exactly what formulation of the end-to-end principle are you 
> referring to in this paper when you indicate that SAM preserves it in 
> IPv6?

Thanks for the remark.
There should be a reference, e.g. to RFC 1958.
What is meant is IP-layer network transparency, e2e.
Addresses and ports that are seen by two communicating applications must 
be the same at both ends.

> My understanding of the end-to-end principle is that it has to do with 
> putting intelligence at the edges of the network (in hosts vs. 
> routers/middleboxes) and with putting certain function at the top of 
> the protocol stack (apps layer vs. lower layers).  This is based on my 
> understanding (and recollection) of a paper by Jerry Saltzer, D. Reed 
> and Dave Clark written in the mid 1980s, which you can find here:
>
> http://web.mit.edu/Saltzer/www/publications/endtoend/endtoend.txt
>
> It is also reasonably well-summarized in this Wikipedia article.
>
> http://en.wikipedia.org/wiki/End-to-end_principle
>
> Based on my understanding of the end-to-end principle, I don't see any 
> significant difference in SAM vs. NAT66 WRT how much they maintain (or 
> violate) the end-to-end principle, as both mechanisms place some 
> functions/intelligence in the infrastructure.
With SAM, hosts know their global addresses, and can use them, e.g. with 
SCTP or Shim6.
In my understanding, this is a difference (an an important one).

Regards,

RD



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