PA and PI: Two Types of IP Address Space
When buying IPv4 addresses, you will encounter two main allocation types: PA (Provider Aggregatable) and PI (Provider Independent). Understanding the difference is important because it affects how you can use, transfer, and manage the addresses.
Provider Independent (PI) Space
What Is It?
PI addresses are assigned directly to end-user organizations by an RIR (or through a sponsoring LIR). The holder can use these addresses independently of their internet service provider.
Key Characteristics
- Portable between providers - you keep the IPs if you switch ISPs
- Requires RIR membership or a sponsoring LIR for maintenance
- Directly transferable under standard RIR transfer policies
- Can be announced from any AS number
- Typically used by end-user organizations, not ISPs
Provider Aggregatable (PA) Space
What Is It?
PA addresses are allocated to LIRs (ISPs/hosting providers) for assignment to their customers. The LIR holds the allocation and is responsible for the address space.
Key Characteristics
- Allocated to LIRs for customer assignment
- Can be sub-allocated and assigned to end users
- Transfer involves the LIR that holds the allocation
- Often available in larger blocks
- May require additional steps when changing the holding LIR
Comparison Table
| Feature | PI | PA |
|---|---|---|
| Holder | End user | LIR/ISP |
| Portability | High - ISP independent | Tied to LIR allocation |
| Transfer complexity | Standard | May involve LIR changes |
| Typical block size | /24 to /22 | /22 and larger |
| Price | Standard market rate | Sometimes 5-10% less |
| Best for | End users, portability | ISPs, hosting, large deployments |
Which Should You Choose?
- Choose PI if: You are an end user, want maximum portability, or plan to change providers
- Choose PA if: You are an ISP/LIR, need larger blocks, or want to assign addresses to customers
Our marketplace clearly labels each listing as PA or PI so you can make an informed decision.