Re: [Softwires] MAP compatibility with DS-Lite

On 20 November 2013 20:54, Simon Perreault <simon.perreault@viagenie.ca>wrote:

> WG,
>
> draft-ietf-softwire-map-08 contains this:
>
> 7.3. Backwards compatibility
>
>    A MAP-E CE provisioned with only the IPv6 address of the BR, and with
>    no IPv4 address and port range configured by other means, MUST
>    disable its NAT44 functionality.  This characteristic makes a MAP CE
>    compatible with DS-Lite [RFC6333] AFTRs, whose addresses are
>    configured as the MAP BR.
>
> In view of the recent discussions on provisioning, this functionality
> strikes me as useless. There would be no reason for an ISP to use such
> provisioning. A unified CPE would just do DS-Lite if that's what's
> available.
>
> I suggest to remove that section.
>

You seem to equate ds-lite to being only there if it uses ds-lite dhcpv6
extensions, which is not correct.
Consider the case where a MAP deployment has a need (for whatever reason)
to direct some CPEs to an AFTR (stateful NAT). Instead of rolling out
Ds-lite DHCP extensions all over, it is trivially simple to achieve the
desired effect with the above MAP CE behaviour in place.
This does not mean that those who want to use DS-lite dhcp extensions
cannot do so, if available. But it does mean that those who deploy MAP,
don't have to take care of mandating ds-lite dhcp extensions "just in case"
all over the shop.
As such, the functionality is IMO useful, and almost trivial to achieve in
an implementation.

-Wojciech.

>
> Simon
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