Subject: [Softwires] MAP-E question -- provisioning of Rule IPv4 prefix

From: Tom Taylor <[email-masked]>
Date: Mon, 08 Apr 2013 18:06:46 -0400

In the previous note, I meant the BMR used as FMR, to be technical. But 
here's another point from the same section:

    The length of r MAY be zero, in which case the complete IPv4 address
    or prefix is encoded in the EA bits.  If only a part of the IPv4
    address/prefix is encoded in the EA bits, the Rule IPv4 prefix is
    provisioned to the CE by other means (e.g.  a DHCPv6 option).

Question: does that second sentence also assume r = 0? If so, I think 
you've moved beyond what makes sense to document as part of MAP-E. Given 
that you have the MAP-E BMR mechanism, why wouldn't you use it?

Tom

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From: Ole Troan <[email-masked]>
Date: Tue, 9 Apr 2013 12:52:56 +0200

Tom,

> In the previous note, I meant the BMR used as FMR, to be technical. But here's another point from the same section:
> 
> Question: does that second sentence also assume r = 0? If so, I think you've moved beyond what makes sense to document as part of MAP-E. Given that you have the MAP-E BMR mechanism, why wouldn't you use it?

no, the second sentence assumes r > 0. "If only a part of the IPv4 address is encoded...", implies that
the other part comes via the BMR.

cheers,
Ole

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From: Tom Taylor <[email-masked]>
Date: Tue, 09 Apr 2013 07:11:57 -0400

I'd suggest adding the condition at the start of the second sentence to
be sure it is read correctly:

    "If r is non-zero but only a part ..."

The other thing bothering me about that sentence is that it is talking 
about provisioning of the Rule IPv4 index in isolation, when it is 
actually part of the BMR. Why not simply say, for the complete sentence:

    "If r is non-zero but only a part of the IPv4 address/prefix is 
encoded in the EA bits, the missing initial portion is provided by the 
Rule IPv4 prefix from the BMR."

On 09/04/2013 6:52 AM, Ole Troan wrote:
> Tom,
>
>> In the previous note, I meant the BMR used as FMR, to be technical.
>> But here's another point from the same section:
>>
>> The length of r MAY be zero, in which case the complete IPv4
>> address or prefix is encoded in the EA bits.  If only a part of the
>> IPv4 address/prefix is encoded in the EA bits, the Rule IPv4 prefix
>> is provisioned to the CE by other means (e.g.  a DHCPv6 option).
>>
>> Question: does that second sentence also assume r = 0? If so, I
>> think you've moved beyond what makes sense to document as part of
>> MAP-E. Given that you have the MAP-E BMR mechanism, why wouldn't
>> you use it?
>
> no, the second sentence assumes r > 0. "If only a part of the IPv4
> address is encoded...", implies that the other part comes via the
> BMR.
>
> cheers, Ole
>