Re: [Softwires] MAP Open issues: Interface-id

[GangChen <[e-mail]>]

2011/11/8, Ole Troan <[e-mail]>:
>>> 1. Checksum neutrality being an open question, it is relevant here.
>>> 2. It is useful AFAIK to distinguish CE addresses from BR addresses.
>>>
>>> The best proposal I know so far is as follows (with CNP = Checksum
>>> neutrality preserver)
>>>
>>> CE ADDRESS
>>>
>>> <- - - - - - IPv6 Unformatted  address (104 bits) - - - ->
>>> +-------------------+----------+----------+---------------+
>>> | Rule IPv6 prefix  |IPv4 suff.| Max PSID |  Padding = 0  |
>>> +-------------------+----------+----------+---------------+
>>> :
>>> :<- - - - - - - - - 64  - - - - - >:<- - - - 40 - - - - ->:
>>> :                                  :\                      \
>>> :                                  <8>                      :<- 16 ->
>>> :                                  : :                      :        :
>>> +----------------------------------'-'----------------------+--------+
>>> | IPv6 unformatted address (part 1)|V|                      |   CNP  |
>>>
>>> +----------------------------------+-+----------------------+--------+
>>> <- - - - - - - - - - -  IPv6 address (108 bits)  - - - - - - - - - - >
>>>
>>>
>>>
>>> BR ADDRESS
>>>
>>> +------------------------------------+-+-----------------+-+-------+
>>> |              BR IPv6 prefix        |V|   IPv4 address  |0|  CNP  |
>>> +------------------------------------+-+-----------------+-+-------+
>>> < - - - - - - - - - 64  - - - - - - ><8><- - -  32 - - -><8><  16  >
>>>
>>
>> +1
>> The checksum neutrality is desirable for translation case.
>> I suggest to take above format into consideration
>
> the consequence of that is that the destination IPv6 address will change for
> every flow.
> the MAP node cannot any longer listen to a single IPv6 address for MAP
> traffic, but has to intercept packets for a whole prefix.

Yes. I see there are two choices when MAP nodes process incoming packages
i) Should we let MAP node interface bind to a single static IPv6 address
ii) Should we let MAP node interface bind to a route to
IPv4-translatable IPv6 prefix

In translation case, above two cases are possible. That is
implementation specific. So I suggest to put above design as int-id
candidate for more inputs from the community

BRs

Gang