What are Provider Aggregatable (PA) addresses and Provider Independent (PI) addresses?
PA addresses are assigned from an LIR's allocation and are registered in the RIPE Database by the LIR. The advantage of PA addresses is that the routing information for many customers can be aggregated once it leaves the provider's routing domain.
PI address space is assigned separately and not from an LIR's PA allocation. All PI assignments are registered in the RIPE Database by the RIPE NCC at the time they are assigned. PI assignments are usually small; they cannot be aggregated into larger blocks. The disadvantage of this is that networks operators throughout the Internet may choose not to route them.
As the RIPE NCC has begun to allocate IPv4 address space from the last /8, no new IPv4 PI address space can be assigned. This is in accordance with section 5.1 of ". IPv6 PI address space is still available. "