Re: [Softwires] 4rd Address Mapping - version-01

[Jacni Qin <[e-mail]>]

hi

On 10/17/2011 8:26 PM, [e-mail] wrote:
> Hi,
> This is my command in line.
>
>>
>>>     therefore my answer to Q1, is NO, unless we carefully select
>>>     IPv4 addresses for CEs with giving up to use some of them, which
>>>     have been so precious.
>>>     Q2. then it must fine as long as we map them to different Rule
>>>     IPv6 Prefix. (?)
>>>     suppose CE1 is the same as (1). for 64.32../16, we use a longer
>>>     stuff.
>>>     however, there is a CE3:
>>>     Rule IPv6 Prefix B: 20010db8 (2001:db8::/29)
>>>     CE3 IPv4 address: 4020 1876 (64.32.24.118)
>>>     CE3 PSID: 54
>>>     CE3 CE index: 987654
>>>     ---------------------------------------------------------------
>>>     (3) CE3 IPv6 prefix: 20010db 987654 (2001:db9:8765:4000::/52,
>>>     woops!)
>>>     ambiguity happens. then we may argue: using the ugly
>>>     Rule_IPv6_Prefix_B is the root of the problem! we have not to
>>>     use a prefix covered by another.
>>     No, I think the bits of the same position are not additive. So,
>>     it should be a delegated prefix of "/53", right?
>>
>>
>> :P sorry for the typo but i have pointed out in the errata. :P
>> however, even though this is /53, and you will have, in the route
>> table, both
>> 2001:db9:8765:4000::/52 => route to CE1
>> 2001:db9:8765:4000::/53 => route to CE3
>>
>> but for the packet encapsulated with the destination address
>> 2001:db9:8765:4000::200:5efe, you couldn't decide the route should go
>> to CE3 instead of CE1. here the longest-match doesn't work. right?
> I guess the second delegated prefix should be 2001:db8:1876:5400::/53
> I guess the second delegated prefix should be 2011:db8:c3b2:a000::/53.
Oops, sorry. ;-)

> Because the CE3 Rule IPv6 Prefix length is not mulitipe of 4 bits,it
> need calculate using Binary as follows.
>
> v(/29)
> --elipsis(0x2001 0db)--1000 (2011:db8::/29)
> --elipsis(0x4020)------ 000 1100 0011 1011 0 (64.32.24.118)
> 010 1010 0 (PSID 0x54)
> --------------------------------------------------------------------------
> CE3 IPv6 prefix: 2001:db8:c3b2:a000::/53
>
> If the CE3 IPv4 address is 64.32.48.236, CE3 PSID is 0xa8, calculate
> as follows,
> v(/29)
> --elipsis(0x2001 0db)--1000 (2011:db8::/29)
> --elipsis(0x4020)------ 001 1000 0111 0110 0 (64.32.48.236)
> 101 0100 0 (PSID 0xa8)
> --------------------------------------------------------------------------
> the CE3 IPv6 prefix is 2001:db9:8765:4000::/53
>
> I think this should be not gonna happen, since the IPv6 address
> planing must be done natively
> considering nothing about the IPv4 address. As exclusiveness, each CE
> has unique CE IPv6 Prefix.
>
> As described in the example Maoke given, since "Rule IPv6 Prefix B" is
> contained in the "Rule IPv6 Prefix A",
> if the IPv6 addresses under Rule IPv6 Prefix A and the IPv6 address
> under Rule IPv6 prefix B are assigned independently
> and have any consideration each other, same CE IPv6 prefix assigning
> to different CEs may be happen. I think this MUST be
> avoided when designing the mapping rules or setting the IPv6 assigning
> way(such as DHCPv6 etc.).
>
The address assignment under one given prefix should be done with
considerations to avoid conflicts.


Cheers,
Jacni

> Cheers
>
> Chunfa
>
>