Re: [Softwires] MAP and 4rd - Relationship with Single translation

[Wojciech Dec <[e-mail]>]

On 19 March 2012 14:22, Rémi Després <[e-mail]> wrote:

> Hi, Xing,
>
> I look forward to face to face discussions in Paris if we don't clarify
> everything before that (I will be busy on something else in the next 3
> days).
>
>
> Le 2012-03-18 à 23:39, Xing Li a écrit :
> ...
>
>
>   A key point is that 4rd doesn't prevent a 4rd-capable dual-stack CE
> node, when it receives no 4rd mapping rule, to exercise single translation.
>  Actually, I believe that using for this the BIH of RFC6535 is both
> sufficient and recommendable.
>  Translated IPv4 packets, because they are sent from CE nodes to DNS64
> synthesized addresses, are appropriately routed to their destinations. (It
> can be via the NAT64-CGN if needed, or via more direct paths if possible.)
> Anything missed?
>
>
> Sorry, this is a misunderstanding.
> Hint: Single translation and double translation are based on the same
> mapping rule in the CERNET2 deployment.
>
>
> I am well aware of this, but this doesn't explain why 4rd mapping rules
> similar to those of CERNET2 wouldn't have, like MAP-T, "IPv4 to IPv6
> communication (single translation) supported".
>
> As said in RFC6219, CERNET hosts have their IPv6 addresses configured "via
> manual configuration or stateful autoconfiguration via DHCPv6".
> Hosts can therefore be assigned Interface IDs that have the 4rd-u format
> (with V octet and CNP).
>
> Now, when both addresses happen to be checksum neutral, RFC6145
> translation doesn't modify L4 data, so that it doesn't matter whether the
> DS node has used 4rd-u header mapping or single translation.
> Thus, IPv6-only hosts can exchange packets with IPv4 applications of 4rd
> CE nodes.
>

If those packets are UDP checksum 0, the IPv6 host would either need to be
customized, or something else would need to changed/configured on the 4rd-u
CE specifically to get that to work for specific IPv6 destinations, while
with MAP-t this would be transparent (and not require specific forwarding
rules).

-Woj.


>
> Regards,
> RD
>
>
>
>
>
>
>
> Regards,
>
> xing
>
>
>
>  Regards,
> RD
>
>
>
>
>
>  Regards,
>
> xing
>
>
>
>  Regards,
> RD
>
>
>
>
>
>  Le 2012-02-10 à 04:28, Xing Li a écrit :
> ... | | | | |
>
>     |  5 | IPv6 web caches work for IPv4        |  Y  |  N  |  Y  |  N  |
>   |    | packets                              |     |     |     |     |
>
>  suggest you rename to "IPv4 to IPv6 communication (single translation) supported"
>
>
>
> (2) More clarification should be added here. I am not sure 4rd-H can
> support single translation.
>
> (a) According to (1), 4rd-H does not perform header translation defined by
> RFC6145.
>
> (b) In the softwire mailing list, it seems that 4rd-H cannot support
> single translation.  See the thread containing
> http://www.ietf.org/mail-archive/web/softwires/current/msg03324.html and
> other posts.
>
> (c) If 4rd-H cannot support single translation, then "IPv6 web caches work
> for IPv4 packets" requires special configurations, it cannot do IPv6 web
> caches for non 4rd-H packets.
>
>
>  ...
>
>  (5) I would like to see the details of how 4rd-H handles ICMP and ICMP
> error messages. In the softwire mailing list there were some discussions. See
> the thread containing
> http://www.ietf.org/mail-archive/web/softwires/current/msg03324.html and
> other posts. Please add
>
>  | 17 | Handle ICMP (RFC6145) | Y | n/a | ? | ? |
>
>  ...
>
>
>
>
>
>
>
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