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

[GangChen <[e-mail]>]

Hello Maoke,

Thanks for the discussion.
Please my reply inline.

2011/10/9, Maoke <[e-mail]>:
> hi Gang,
>
> thanks for the reply.
>
> 2011/10/9 GangChen <[e-mail]>
>
>> >> Yes, in padding case.
>> >>
>> >>
>> > what do you mean with the "yes"? do you mean having a short-enough
>> Rule-IPv6
>> > is a prerequisite for deploying 4rd-pd?
>> >
>> > for example, a small ISP has its Rule IPv4 prefix such as 10/8, while
>> > its
>> > total IPv6 block is a /48 or a /56 prefix only. the ISP is deploying
>> > stateless transition, possibly 4rd-pd. is such an ISP surely able to pad
>> > necessary part of IPv4 address in the first 64 bits?
>>
>> I guess I have already put some comments on that. Please see below.
>>
>>
> do you mean you *require" every ISP surely having IPv6 prefix shorter than,
> e.g., /32?

I'm not sure what formula you have to deduce this *requirement*.
Different sharing ratios should implicitly be expressed by different
IPv6 prefix lengths when an operator would deploy PD. At this point,
you can't help even you encode whole IPv4 address in suffix. As for
the question you raised, I think that are operational issues more than
technical issues. I take your example as explanation for your better
understanding.

A small ISP has its Rule IPv4 prefix such as 10/8, while its total
IPv6 block has fairly long prefix like /48 or a /56.

Then an operator could strategically pre-config a relatively small
IPv4 subnet to 4v6 domain as rule IPv4 prefix, like 10/24. Then you
could get more space in IPv6 prefix to put PSID information. See that
is quite flexible if you do have a good operational planning.



>may i beg you answer this question without equivocation. :)
> thanks!

Sorry for the confusion. I hope above explanation could help.

>> > i don't think all current practices are "trying to encode the
>> > information
>> in
>> > the first 64bits". to my humble understanding, at least divi-pd encodes
>> the
>> > IPv4 full address information, which identifies a specific user, not in
>> the
>> > first 64 bits.
>>
>> Thanks for the clarification. That is why you propose to insert full
>> IPv4 address?
>>
>>
> well, i didn't propose anything new. some cases need full IPv4 addresses
> while these cases are included in our discussion on the unified address
> mapping.

I only see your one case here.

>
>> > in your proposal draft-chen-softwire-4v6-pd-00, you have
>> >
>> >   Delegated IPv6 prefix = IPv6 prefix + Add set + Port set
>> >
>> > where your Add-set is (32 - IPv4_pref_len) long, right? if the
>> IPv4_pref_len
>> > = 8 while the IPv6_prefix_len = 48, can your first 64bits identify a
>> user?
>> >
>>
>
> on the other hand, may you also answer this question?

See above example. BTW, I have never said the IPv6 prefix in
draft-chen-softwire-4v6-pd-00 could identify each user.
What I said in a previous email is MAX PSID in addrmapping-01 could
help to identify a specific user. Please don't get me wrong.

Many thanks

Gang