Re: [Softwires] IPv4 Residual Deployment - Unified-standard proposal 4rd

[Maoke <[e-mail]>]

2012/3/15 Maoke <[e-mail]>

>
>
> 2012/3/15 Rémi Després <[e-mail]>
>
>>
>> Le 2012-03-15 à 10:02, Maoke a écrit :
>>
>>
>>
>> 2012/3/15 Rémi Després <[e-mail]>
>>
>>> Maoke,
>>>
>>> Let's try, once more, to understand each other.
>>>
>>> If we assume that MAP-T CEs (and BRs) now MUST translate DCCP (which
>>> is AFAIAC a positive result of our discussion):
>>> a) Such a CE can communicate with an IPv6-only host including in DCCP.
>>> b) The same would apply to UDP lite if MAP-T would also require UDP-lite
>>> translation.
>>> c) If a MAP-T CE communicates via a NAT64 (which is based on RFC6145,
>>> i.e. with DCCP optional), DCCP is broken if the NAT64 doesn't translate
>>> DCCP (as permitted by RFC6145).
>>> d) If RFC6146 (NAT64) and/or RFC6145 would be modified to also impose
>>> DCCP translation, nodes complying with modified versions and those
>>> complying with previous versions wouldn't be guaranteed to interwork for
>>> DCCP.
>>>
>>> If we don't agree on this, there is still something to be clarified
>>> between us.
>>>
>>
>> surely do not. RFC6146 clearly states:
>>
>>    The current specification only defines how stateful NAT64 translates
>>    unicast packets carrying TCP, UDP, and ICMP traffic. Multicast
>>    packets and other protocols, including the Stream Control
>>    Transmission Protocol (SCTP), the Datagram Congestion Control
>>    Protocol (DCCP), and IPsec, are out of the scope of this
>>    specification.
>>
>>
>> I said "If RFC614... would be modified to also impose DCCP translation"
>> => I take the point that you are not interested in that, but I don't think
>> there was a contradiction.
>> OK?
>>
>
> it is not yet modified. with the current statement of RFC6146, the current
> equipment doesn't support DCCP. if it is modified, the update may state
> mandatory imposement for DCCP. i don't see any problem here.
>

more clearly speaking: stateful NAT64, i think, only needs to be done once
in a delivery, therefore either the DCCP is supported or it is not. there's
no "interwork" between NAT64 who has been modified with the NAT64 who has
not. incorrect?


> on the other hand, i cannot understand how the CNP helps stateful checksum
> validity. may you please to clarify?
>
> maoke
>
>
>>
>> RD
>>
>>
>>
>> - maoke
>>
>>
>>> If we agree, I have nothing else on this point.
>>>
>>> Regards,
>>> RD
>>>
>>>
>>>
>>> If, as you suggest,
>>> 2012-03-15 02:04, Maoke:
>>>
>>> 2012/3/14 Rémi Després <[e-mail]>
>>>
>>>>
>>>> Le 2012-03-14 à 10:46, Maoke a écrit :
>>>>
>>>>
>>>> 2012/3/14 Rémi Després <[e-mail]>
>>>>
>>>> ...
>>>
>>>
>>>>> Changing DCCP support from optional to mandatory in RFC6145 isn't
>>>>> backward compatible (an upgraded node isn't guaranteed to interwork with a
>>>>> non upgraded node).
>>>>>
>>>>
>>>> the CE/BR specified RFC6145-compliant might be a problem but MAP-T is
>>>> still in development. if we state to enforce DCCP mandatorily rather than
>>>> optional in MAP-T, a MAP-T-compliant CE/BR won't has the backward
>>>> compatible problem. to this extend, MAP-T is at the same kick-off line of
>>>> the 4rd-U.
>>>>
>>>>
>>>> 1. I agree that, between CEs and BRs, there can be no problem for DCCP
>>>> (provided the draft is completed to this effect). The comparison table was
>>>> explicitly made with existing drafts, and intended to be updatable.
>>>>
>>>> 2. The MAP-T draft is also claimed to allow "communication between
>>>> IPv4-only, as well as any IPv6 enabled end hosts, to native IPv6-only
>>>> servers in the domain that are using IPv4-mapped IPv6 address". In
>>>> this case, AFAIK, the backward compatibility problem exists
>>>> Thought?
>>>>
>>>
>>> surely it does not exist. that statement applies to the MAP-T-compliant
>>> equipments, when it is used as a IPv4-to-IPv6 single translator or as an
>>> native IPv6 router. same deployment of equipments should support
>>> double-translation, single-translation, and native IPv6 accesses
>>> simultanenously. that's one of the points of the MAP-T.
>>>
>>> - maoke
>>>
>>>
>>>>
>>>>
>>>>  To be even more precise, H6 of the comparison table can be:
>>>>> "For ISPs that don't provide all CE nodes, and for shared IPv4
>>>>> addresses, DCCP and UDP-Lite are supported, as well as future protocols
>>>>> using the TCP checksum algorithm and ports at the same place"
>>>>>
>>>>
>>>> i actually think the original text is fine. "For .... shared IPv4
>>>> addresses" is not needed for 4rd-U, to my understanding, nor needed to
>>>> MAP-T.
>>>>
>>>>
>>>> Will see what to do, then, when changes to the MAP-T draft concerning
>>>> DCCP are known.
>>>>
>>>
>>>> RD
>>>>
>>>>
>>>>
>>>>
>>>> maoke
>>>>
>>>>
>>>>>
>>>>> Does this cover the point?
>>>>>
>>>>> RD
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> ;-)
>>>>> maoke
>>>>>
>>>>>
>>>>>>
>>>>>>  but this is not my point. my point is: there must be something we
>>>>>> don't know ("non omnia possumus omnes"). even we have gone through the
>>>>>> RFCs, there might be some other proprietary L4 protocols, or experimental
>>>>>> protocols. even they are minority, i don't think ignoring their existance
>>>>>> in our solution fits the spirit of the Internet. it might be argued that
>>>>>> NAT44 doesn't support such L4 protocols now, but an L4 protocol owner may
>>>>>> makes his own NAT44, either attached to the CE or separated. if 4rd-U
>>>>>> respects such an effort, it should state "currently blahblabla L4 protocols
>>>>>> are supported". the similar statement applies to the RFC6145 or MAP as well.
>>>>>>
>>>>>>
>>>>>> i somehow am hard to accept words like "far fetched theoretical
>>>>>> problem".
>>>>>>
>>>>>>
>>>>>> If I had thought it might be so, I would have avoided the word.
>>>>>>
>>>>>>
>>>>>> the L4-recalculate is a generic, architectural solution, surely
>>>>>> needing codes for every L4 protocol. but this generality in architecture
>>>>>> makes RFC6145 or MAP-T equipment be easily enhanced to support anything new
>>>>>> with the same logic. but for the 4rd-U BR, it looks to me we cannot have
>>>>>> the unified logic for all (even limited to existing and well-known) L4
>>>>>> protocols.
>>>>>>
>>>>>> only my 2 cents.
>>>>>>
>>>>>>
>>>>>> With amendments above, the point is AFAIK completely covered:
>>>>>> everything is rigorously true, and worth noting.
>>>>>> Thanks for the useful reference to the RDP of RFC1151.
>>>>>>
>>>>>> RD
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
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>>>
>>
>>
>