Subject: Re: [pcp] OpCopdes (RE: draft-wing-pcp-base-01 posted)

From: <[email-masked]>
Date: Tue, 2 Nov 2010 08:29:45 +0100

Hi Dan,

See inline.

Cheers,
Med 

-----Message d'origine-----
De : Dan Wing [mailto:[email-masked]] 
Envoyé : vendredi 29 octobre 2010 01:10
À : BOUCADAIR Mohamed NCPI/NAD/TIP; 'Reinaldo Penno'; [email-masked]
Objet : RE: [pcp] OpCopdes (RE: draft-wing-pcp-base-01 posted)

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf Of
> [email-masked]
> Sent: Thursday, October 28, 2010 8:34 AM
> To: Reinaldo Penno; [email-masked]
> Subject: Re: [pcp] OpCopdes (RE: draft-wing-pcp-base-01 posted)
> 
> Hi Reinaldo,
> 
> In fact, there are several dimensions to this problem of determining
> the external IP Address.
> 
> Retrieving the capabilities helps to avoid overloading the PCP Server
> in some scenarios: e.g., there is no reason for a PCP Client embedded
> in a dual stack host to issue 4 requests to a PCP Server which controls
> only a NAT44 function.

A dual stack host has not purpose or need to send a PIN64 or PIN46.  It
has only a reason to send PIN66 or PIN44.  I explained that earlier, 
and you must have disagreed because you keep talking about 4 messages.

Med: Yes, I disagree because you can not prevent the case where a dual stack is located behind a NAT46 (using a NAT464 model). Then it will need to open pinholes in NAT46 and/or NAT64. I'm not arguing here that NAT464 is a valid model or not, but PCP should work in any environment where there is an upstream function that should be controlled for the successful delivery of incoming packets.

For an IPv4-only host, without a discovery function it might send
two PCP messages (PIN46, PIN44).  Adding a discovery function doesn't
reduce the number of messages -- it would send a discovery message
message (1 message) and then a PIN46 (2 messages) and/or PIN44 message
(3 messages).  It could, in fact, add a message.

Med: Yes and No. Yes if the discovery if based on PING/PING procedure we are proposing with Reinaldo (BTW, PING/PING procedure is useful for other purposes). And No, if the discovery of the capabilities is undertaken during the discovery of the PCP Server itself. The capabilities of the PCP-controlled device can be done in DHCP when retrieving the IP reachability information of the PCP Server. A Capability Field can be added to the PCP DHCP Option. 

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From: "Dan Wing" <[email-masked]>
Date: Tue, 2 Nov 2010 08:46:04 -0700

> > in a dual stack host to issue 4 requests to a PCP Server which
> > controls only a NAT44 function.
> 
> Med: Yes, I disagree because you can not prevent the case where a dual
> stack is located behind a NAT46 (using a NAT464 model). Then it will
> need to open pinholes in NAT46 and/or NAT64. I'm not arguing here that
> NAT464 is a valid model or not, but PCP should work in any environment
> where there is an upstream function that should be controlled for the
> successful delivery of incoming packets.

The PCP stack and/or the PCP-aware application running on that dual 
stack host is either (a) aware or (b) unaware of the NAT46 (or NAT64)
on its network.

In either case (a) or (b), I don't understand why a dual-stack host
would send a PIN64 or PIN46, because that dual-stack host can use
PIN44 (to get a pinhole to the IPv4 Internet) and PIN66 (to get a 
pinhole to the IPv6 Internet).

> Med: Yes and No. Yes if the discovery if based on PING/PING procedure
> we are proposing with Reinaldo (BTW, PING/PING procedure is useful for
> other purposes). And No, if the discovery of the capabilities is
> undertaken during the discovery of the PCP Server itself. The
> capabilities of the PCP-controlled device can be done in DHCP when
> retrieving the IP reachability information of the PCP Server. A
> Capability Field can be added to the PCP DHCP Option.

Ok.  Noted.

-d

---

From: <[email-masked]>
Date: Tue, 2 Nov 2010 16:55:07 +0100

Re-,

See inline.

Cheers,
Med 

-----Message d'origine-----
De : Dan Wing [mailto:[email-masked]] 
Envoyé : mardi 2 novembre 2010 16:46
À : BOUCADAIR Mohamed NCPI/NAD/TIP; 'Reinaldo Penno'; [email-masked]
Objet : RE: [pcp] OpCopdes (RE: draft-wing-pcp-base-01 posted)

Med: In the NAT464 model, there is no NAT44. IPv4 Internet is provided through the NAT46 (e.g., in the CPE) + NAT64 (e.g., located in the boundary between IPv6 realm and IPv4 Internet). Please correct me if I missed your comment.