Re: [Softwires] The port mapping issue

Dear Tom,

Thanks for bringing this up. I think Suresh's proposal (as is described in your mail) is fair enough. IMHO, for Lightweight 4 over 6 contiguous is enough (a = 0). While for MAP-E, considering PSID is required for the construction of IPv6 prefix, arbitrary value is necessary for that use.

Best Regards,
Qi
> 
> Thanks, Woj. I think I started off in the wrong direction, and should focus specifically on Suresh's proposal: GMA for both Light-Weight 4 over 6 and MAP-E, with default a=0 for the former and a=6 for the latter.
> 
> When a=0, the GMA algorithm does degenerate to assigning ports as a single contiguous range per CPE. Min_port for a given PSID is given by the formula PSID * range size, or, in the notation of MAP-E section 5.1, PSID * 2^m. Max_port is given by Min_port + range size - 1.
> 
> With MAP-E, range size is inferred indirectly from the combination of the IPv4 prefix length in the Basic Map Rule and the number of EA bits. This information is not available for Light-Weight 4 over 6. Hence I believe the proposal to use GMA with a=0 for the latter amounts to explicit provisioning of PSID and range size to both the BR and the CPE.
> 
> 
> 
> 
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