Provider Aggregatable Address Space

Provider Aggregatable Address Space (PA address space) are Internet protocol addresses that are assigned by a Regional Internet Registry (RIR ) to a Local Internet Registry (LIR ) ( of allocated ), which divides it into smaller networks (sub -allocated ) and their clients to do so ( assigned).

Usually buys example a smaller ISP connection (upstream) to another party networks with a larger (usually a LIR) and receives from that in justified cases PA IP addresses when it itself does not have its own PI addresses. This leads to difficulties when the smaller providers use multiple Internet connections or change its upstream provider wants, because the IP addresses remain with the LIR and must be returned.