Simon Perreault wrote, on 08/02/2011 09:24 AM:
> Satoru Matsushima wrote, on 08/01/2011 10:41 PM:
>> Thanks, a clarification has made to clear a confusion of restricted port
>> set/ranges and NAT session table limitation. Even if a CPE is allocated 256
>> ports, NAT session can be made over 900G sessions in theory. ('2^32'<Full
>> 32bits v4 address> - '2^29'<class-D/E> - '2^7'<0/8,127/8>) * 2^8<256 ports>.
>
> This is only true for endpoint-dependent NATs, which are forbidden by the
> BEHAVE
> RFCs (4787 and 5382). According to these RFCs, NATs MUST have
> endpoint-independent mapping behaviour. This means that each NAT session will
> consume one external port.
Sorry, I confused the terminology. Each NAT *binding* will consume one external
port. There may be multiple session to different destinations using the same
external port. The 900G figure is valid, as long as internal hosts reuse the
same source address+port for different destinations.
Simon
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