Le 20 juil. 2011 à 18:25, Wojciech Dec a écrit :
>>> ...
>>>> If packets are sent to that address, they
>>>> get passed to NAT44. Hosts behind the CPE or apps on the CPE will not
>>>> use/bind to that address.
>>>
>>> AFAIK, this prohibits using the full CE-assigned IPv6 on the CE LAN side.
>>> Such a constraint isn't needed with "4V6 encapsulation".
>>
>> No.
A justification of this "no" is missing, because:
- The CE 4V6 address is synonymous with a valid IPv6 address in the range
defined by the CE IPv6 prefix.
- With 4V6T, a translated IPv4 packet entering a 4V6 site cannot be
distinguished from an IPv6 packet destined to this valid IPv6 address.
An example:
Host
H
+-+ router
| |< 2001:db8:a::
| |--------------. .-.
| | | | |< 2001:db8:a::/64 4V6T CE
+-+ LAN |--| |-----------------. +-+
| | | | | |< 2001:db8:a:/56
--------------' '-' LAN |---| |------------
| +-+ <= IPv6 packet
----------------' sent to host H
- The IPv6 address of host H has a permitted value (at least per sec 3.2.1 of
RFC 3041 on privacy addresses).
- It is the same as the CE 4V6 address, per current drafts on 4V6
specifications.
=> The IPv6 packet sent to X form the Internet is taken by the 4V6T CE as a
translated IPv4 packet.
It is submitted to the CE NAT44.
It won't therefore reach its destination.
With a 4V6E CE, the CE recognizes that the IPv6 packet doesn't contain an
encapsulated IPv4 packet.
It therefore forwards it in IPv6 on its LAN side.
If this is wrong, thank you for an explanation.
RD
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