Re: [Softwires] Unified Softwire CPE: draft-bfmk-softwire-unified-cpe

[Simon Perreault <[e-mail]>]

Le 2012-11-30 15:18, [e-mail] a écrit :
>> MAP-E:
>> - Lw4o6 set of provisioning information
>> - Forwarding mapping rules
>
> Med: Because of the dependency between the IPv4 address/IPv6 prefix, additional parameters are needed for MAP. This is why the table included two entries for MAP.

I don't follow. A MAP default mapping rule is exactly like a forwarding 
mapping rule, with added semantics saying "this chunk of IPv4 is yours". 
That can be split into a forwarding mapping rule + the usual LW4o6 
parameters, can't you?

>> My intuition is that with a unified CPE we don't need MAP to
>> differentiate between "basic mapping rule", "forwarding mapping rule",
>> and "default mapping rule".
>> - Basic mapping rule is just a forwarding mapping rule + IPv4
>> address +
>> port set.
>> - Default mapping rule is just the remote IPv4-in-IPv6 tunnel endpoint.
>>
>> So in MAP mode we can just provide forwarding mapping rules in
>> addition
>> to the stuff that L4o6 already requires.
>
> Med: you need also MAP parameters (offset, EA-...).

That stuff is included in a "forwarding mapping rule".

>> One thing I expected to see is that if you take a unified CPE
>> that only
>> implements up to LW4o6 mode, and provision it with full MAP mode
>> parameters, it will still work. It will ignore the forwarding mapping
>> rules, and thus will not do mesh networking, but it will still work.
>
> Med: Isn't this covered by the combination of these two points:
>
>     o  A network which supports one or several modes MUST return valid
>        configuration data allowing requesting devices to unambiguously
>        select a single mode to use for attachment.
>
> and
>
>     (1)  If a given mode is enabled (DS-Lite, Lw4o6 or MAP-E), the CPE
>          MUST be configured with the required provisioning information
>          listed in Table 4.  If all of the required information is not
>          available locally, the CPE MUST use available provisioning means
>          (e.g., DHCP) to retrieve the missing configuration data.
>
> If one mode is enabled, the CPE won't ask for more than what it needs.
> If its receives more, it will ignore them. I can add this to text if you think it is missing.

I think it would be good, and I would even add a specific example of 
what happens if you plug a LW4o6 CPE in a MAP-enabled network. (What I 
wrote above.)

Thanks,
Simon
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