What are Provider Aggregatable (PA) addresses and Provider Independent (PI) addresses?

Provider Aggregatable addresses are assigned from an LIR's allocation. PA assignments 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.

Provider Independent address space is assigned separately, most often from RIRs and not from an LIR's PA allocation. All PI assignments are registered in the RIPE Database. PI ranges 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.