Re: [pcp] PREFIX64 PCP Option for NAT64: draft-boucadair-pcp-nat64-prefix64-option

["Tirumaleswar Reddy (tireddy)" <[e-mail]>]

Hi Med -

You may want to look into draft  http://tools.ietf.org/html/draft-ietf-behave-nat64-discovery-heuristic-11 which already addresses this problem and also refers to cases where multiple Pref64::/n exist.

--Tiru.

> -----Original Message-----
> From: [e-mail] [mailto:[e-mail]]
> Sent: Thursday, September 06, 2012 6:50 PM
> To: Simon Perreault; [e-mail]
> Subject: Re: [pcp] PREFIX64 PCP Option for NAT64: draft-boucadair-pcp-nat64-
> prefix64-option
> 
> Hi Simon,
> 
> Before answering your questions, I would like to say some words about the
> context of this work: In fact we have ported a SIP UA implementation to be
> PCP-aware and tested it IPv6-only environment + NAT64 in using both Wifi and
> 3G connectivity. The challenge was
> 
> (1) to place successful communications between IPvx/IPvy UAs without requiring
> any particular mechanism in the SIP Proxy Server and ALG in the NAT64
> (2) use PCP to control the NAT64
> 
> IPv6-only UA needs to be provisioned with the PREFIX64 used by the PCP-
> controlled NAT64 for local synthesis of IPv4-embedded IPv6 addresses.
> 
> Retrieving the PREFIX64 used by the PCP-controlled NAT64 using PCP was a
> natural approach rather than mandating to support a dedicated DHCP option;
> mainly for the following reasons:
> 
> * DHCPv6 is not supported by some mobile UEs
> * We need to correlate a PREFIX64 and a NAT64 device
> 
> Below some answers.
> 
> Cheers,
> Med
> 
> 
> >-----Message d'origine-----
> >De : [e-mail] [mailto:[e-mail]] De la
> >part de Simon Perreault
> >Envoyé : jeudi 6 septembre 2012 14:36
> >À : [e-mail]
> >Objet : Re: [pcp] PREFIX64 PCP Option for NAT64:
> >draft-boucadair-pcp-nat64-prefix64-option
> >
> >Interesting... I have a question:
> >
> >Consider a PCP client that receives a MAP response containing
> >a PREFIX64
> >option. Does the option apply a) only to the mapping contained in the
> >MAP response, or b) to all future mappings as well?
> 
> Med: I'm tempted to say the prefix will be used for all mappings associated
> with the same PCP server. A record to associate a PCP server and a PREFIX64
> should be maintained by the client. We need to check if there are scenarios
> where the same PCP Server controls NAT64s configured with distinct PREFIX64
> servicing the same IPv6-only host.
> 
> >
> >If a), how is PREFIX64 of any use to the client?
> 
> Med: I'm not sure I get your question; but PREFIX64 will be used whenever
> needed to construct IPv4-embedded IPv6 addresses. This is needed particularly
> for services which does not involve DNS64.
> 
> >
> >If b), why include it in a MAP response? Why not DHCP or
> >something else?
> 
> Med: You can include it in DHCP but for mobile terminal not supporting DHCPv6
> this may not help.
> 
> >What happens if the client receives two MAP responses with conflicting
> >PREFIX64 options? Does it have to check that?
> 
> Med:  If we assume a PCP Server controls only one NAT64/PREFIX64, then it is
> safe the client to check whether only one PREFIX64 is learned for each PCP
> Server.
> 
> >
> >Simon
> >--
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