Re: [BEHAVE] RFC3484-revise and NAT64 Well-Known Prefix

[Arifumi Matsumoto <[e-mail]>]

Hi,

thank you for insightful comments on this issue, all.
I'll put some texts in the next version to note discussions about it.

Best regards,

On 2011/03/29, at 19:47, Suresh Krishnan wrote:

> Hi Dan/Teemu(s)/Cameron,
>  I am afraid there is no single right answer here. There will be networks that will prefer NAT44 over NAT64 and those that prefer NAT64 over NAT44. For this reason, I think this is better left as a site-specific policy decision for distribution using a mechanism such as draft-ietf-6man-addr-select-opt. So, I agree with Dan and Cameron that we should not add an entry to the default table for the NAT64 prefix.
> 
> Cheers
> Suresh 
> 
>> -----Original Message-----
>> From: [e-mail] 
>> [mailto:[e-mail]] On Behalf Of Dan Wing
>> Sent: Monday, March 28, 2011 2:48 PM
>> To: 'Teemu Kiviniemi'; [e-mail]
>> Cc: [e-mail]; [e-mail]
>> Subject: Re: [BEHAVE] RFC3484-revise and NAT64 Well-Known Prefix
>> 
>>> -----Original Message-----
>>> From: [e-mail] [mailto:[e-mail]] 
>> On Behalf 
>>> Of Teemu Kiviniemi
>>> Sent: Sunday, March 27, 2011 9:53 PM
>>> To: [e-mail]
>>> Cc: [e-mail]; [e-mail]
>>> Subject: Re: RFC3484-revise and NAT64 Well-Known Prefix
>>> 
>>> On Sun, 27 Mar 2011, [e-mail] wrote:
>>> 
>>>> I discussed shortly with Arifumi about RFC3484 default 
>> policy table 
>>>> updates and NAT64 WKP, i.e. whether the default policy 
>> table should
>>> take
>>>> a stand on 64:ff9b::/96 preference.
>>>> 
>>>> It seemed to us that default policy table does not 
>> necessarily have
>>> to,
>>>> as it could be ok to handle addresses with WKP similarly to global
>>> IPv6
>>>> addresses. Furthermore, the default policy table anyway 
>> cannot cover 
>>>> Network-Specific Prefixes.
>>>> 
>>>> Hence prefixes used for protocol translation would be 
>> handled like 
>>>> global IPv6 addresses unless something different is 
>> configured via 
>>>> policy distribution mechanism? And this should perhaps be 
>> documented 
>>>> into the RFC3484-revised.
>>> 
>>> I believe native IPv4 should always be preferred over 
>> NAT64. Even if 
>>> native IPv4 was using NAT, it is likely to work better with current 
>>> applications than NAT64.
>>> 
>>> Preferring IPv4 over the NAT64 well-known prefix does not fix the 
>>> problem for network-specific NAT64 prefixes. However, I see 
>> no reasons 
>>> why the
>>> NAT64 WKP should not be given a lower preference than IPv4 
>> by default.
>> 
>> One reason is that it changes behavior for a network using 
>> the well-known
>> NAT64 prefix versus using their own network's NAT64 prefix.  
>> Not to mention they won't know if/when their IPv6 devices are 
>> using the new
>> RFC3484 default table, and will thus start shifting their 
>> preference away from IPv6 (and a NAT64) and towards IPv4 (and 
>> a NAPT44, because let's be real, everyone will have a NAPT44 
>> if we're talking about an
>> RFC3484 change).
>> 
>> Personally, I don't see any benefit to changing RFC3484 table 
>> to accomodate NAT64, assuming there is a way for the host to 
>> learn its NAT64 prefix (draft-korhonen-behave-nat64-learn-analysis).  
>> Assuming there is no standard way to learn the prefix by the 
>> time we would want to standardize rfc3484bis, I see harm in 
>> adding the NAT64 well known prefix 64:ff9b::/96 to the 
>> default policy table.
>> 
>> -d
>> 
>> 
>>> --
>>> Teemu
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>> 
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