Re: [Softwires] Proposed Unified Address Mapping for encapsulation and double-translation

[Maoke <[e-mail]>]

2011/10/6 Ole Troan <[e-mail]>

> > > i couldn't understand why we "don't see such limitation in 4v6
> translation". 4via6 translate the private ipv4 address with 4rd mapping rule
> while the public ipv4 address with RFC6052 algorithm, right? can the both
> case work fine if an ISP can only get a fairly long IPv6 prefix, like /40 or
> even longer?
> > >
> > > Yes, if ISP has /32 IPv6 address, then how to embed 32 bits IPv4
> address and PSID in the first 64 bits?
> >
> > only part of the IPv4 address would be embedded into the first 64 bits
> (not that I think that boundary should be "hard").
> > e.g. if the SP has the prefix 10/8. the user the address 10.1.2.3. then
> only "1.2.3" would be embedded in the address.
> > just like what's done for 6rd.
> >
> > Thanks, Ole. That’s the point! In this case , you can only have part of
> the IPv4 address embedded in the first 64 bits. This embedding does work for
> encapsulation or tunneling, but can NOT work for stateless double
> translation, which requires the whole IPv4 address+PSID embeded for any IPv6
> prefix length.
>
> right, for the outside domain traffic.
> putting the state into the IPv6 destination address doesn't affect routing.
> so this works fine with the case where you give a user a /56, where you
> have to have efficient encoding. for the external to the domain traffic you
> need to encode the full IPv4 address.
>
> cheers,
> Ole


thanks a lot, Ole and Prof. Bao, for the discussion. then i got to fairly
understand the situation. :)

cheers,
maoke