Le 2013-01-27 à 23:07, Tom Taylor <[email protected]> a écrit :

> The examples in my previous note sort of provided backing for my view that 
> the MAP endpoint IPv6 prefix can be limited to a maximum of a /64, thus 
> making the IID fully conformant both to RFC 4291 and to RFC 6052.
> 
> Obviously, the more IPv4 address bits you can stick into the EA bits, the 
> fewer the number of MAP rules you have to provision. The picture of a MAP 
> endpoint IPv6 prefix can be drawn like this:
> 
> 
> +-----------------------------+-------------------+-----------+
> |   Rule IPv6 prefix          |    IPv4 suffix    |    PSID   |
> +-----------------------------+-------------------+-----------+
> |                             |                   |           |
> |  Common to all CEs sharing  | Common to all CEs | Unique to |
> |     the same BMR            | sharing the same  |  this CE  |
> |                             | IPv4 address      |           |
> 
> 
> If we expect a Rule IPv6 prefix to be a /48 and a PSID to be no more than 8 
> bits in length (i.e. CEs get 512 ports each, sharing ratio is 128), limiting 
> the endpoint IPv6 prefix to 64 bits leaves room for eight bits of suffix. 
> That in turn means each mapping rule serves 16384 CEs. If the Rule IPv6 
> prefix backs off to a /40, we can get two million CEs per mapping rule.

> I think limiting the prefix length to 64 bits is reasonable. Comments?

+1
RD

> 
> Tom Taylor
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