Shared Address Space is distinct from RFC 1918 private address space
because it is intended for use on Service Provider networks.
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This memo documents an Internet Best Current Practice.
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A Service Provider can number the interfaces in question from
[RFC1918] space if at least one of the following conditions is true:
o The Service Provider knows that the CPE/NAT works correctly when
the same [RFC1918] address block is used on both its inside and
outside interfaces.
o The Service Provider knows that the [RFC1918] address block that
it uses to number interfaces between the CGN and CPE is not used
on the subscriber side of the CPE.
Unless at least one of the conditions above is true, the Service
Provider cannot safely use [RFC1918] address space and must resort to
Shared Address Space. This is typically the case in an unmanaged
service, where subscribers provide their own CPE and number their own
internal network.
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The Shared Address Space address range is 100.64.0.0/10.
