Attached the answer I had sent to Margaret, but mistakenly not copied to the list (apologies).
I hope it helps.
RD

Dan Wing  -  le (m/j/a) 3/21/09 11:23 AM:
Rémi,

Please do followup to Margaret's post so that at least I can understand SAM-02
better.

-d


  
-----Original Message-----
From: [email protected] [mailto:[email protected]] 
On Behalf Of Margaret Wasserman
Sent: Tuesday, March 17, 2009 12:34 PM
To: Rémi Després
Cc: [email protected]
Subject: Re: [nat66] [Fwd: Re: [BEHAVE] FYI: 
draft-despres-sam-02 enclosed]


Hi Remi,

On Mar 17, 2009, at 5:05 AM, Rémi Després wrote:
    
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.
      
I have read the SAM draft a few times now, and I still don't really  
understand what you are proposing...

I understand how communication could happen across a SAM zone when  
both end nodes have global addresses.  The global packet could be  
encapsulated in an IP header that uses local addresses and routed  
across the SAM zone.  When it leaves the SAM zone, the outer header  
would be removed and end-to-end transparency would be maintained.  I  
also understand how this might be useful in situation where, for  
example,

But, I don't understand how a host that does not know its global  
address can use SAM to communicate with other hosts on the global  
Internet.  If such a host sends from a local source address to a  
global destination address, where is the local source address mapped  
or translated into a global address, so that the global destination  
receives a packet with a source IP address that can be used 
to route a  
packet back to the sender?
    
(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.
      
If you were to change your text to refer to end-to-end transparency  
(as discussed in RFC 1958) instead of the end-to-end 
principle (as is  
also discussed in RFC 3724) that would address my terminology concern.

Margaret

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--- Begin Message ---
Margaret Wasserman  -  le (m/j/a) 3/17/09 8:34 PM:

Hi Remi,

On Mar 17, 2009, at 5:05 AM, Rémi Després wrote:
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.
I have read the SAM draft a few times now, and I still don't really understand what you are proposing...

I understand how communication could happen across a SAM zone when both end nodes have global addresses. The global packet could be encapsulated in an IP header that uses local addresses and routed across the SAM zone. When it leaves the SAM zone, the outer header would be removed and end-to-end transparency would be maintained. I also understand how this might be useful in situation where, for example,

But, I don't understand how a host that does not know its global address can use SAM to communicate with other hosts on the global Internet.
It doesn't.
- If it has SAM and at least one CPE has SAM, then it knows its global address. - Otherwise, it cannot use SAM and, in a private addressing site, e2e transparency is lost. This is why SAM is _complementary_ of the network prefix mapping you have proposed with Fred.
If such a host sends from a local source address to a global destination address, where is the local source address mapped or translated into a global address, so that the global destination receives a packet with a source IP address that can be used to route a packet back to the sender?
> (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.
If you were to change your text to refer to end-to-end transparency (as discussed in RFC 1958) instead of the end-to-end principle (as is also discussed in RFC 3724) that would address my terminology concern.
Thanks.
This should be fixed.

RD



--- End Message ---
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