An ASN (Autonomous System Number) is a unique identifier assigned to networks that control their own routing policies. Learning what an ASN is and how to obtain one is essential for organizations managing their own network infrastructure.
Publish date: 1/21/2026
If you've ever looked into network infrastructure or BGP routing, you've probably come across the term ASN. But what exactly is it, and why would you need one? More importantly, how do you actually get one if your organization requires it?
In this guide, we'll break down what an ASN is, why it matters, who needs one, and walk through the process of obtaining your own.
An ASN, or Autonomous System Number, is a globally unique identifier assigned to an autonomous system (AS). An autonomous system is essentially a collection of IP networks and routers under the control of a single organization that presents a common routing policy to the internet.
Think of an ASN like a postal code for networks. Just as postal codes help route mail to the right location, ASNs help route data packets across the internet by identifying which network they should go to.
ASNs come in two formats:
The internet runs on BGP, and BGP uses ASNs to identify different networks and make routing decisions. When you have your own ASN, you're able to control how your network traffic is routed across the internet, peer with other networks, and announce your IP address blocks to the global routing table.
Not every organization needs an ASN. Most businesses connect to the internet through an ISP and don't require one. However, there are several scenarios where obtaining an ASN becomes necessary or beneficial.
If you want to connect to multiple upstream providers for redundancy and better reliability, you'll need your own ASN. This allows you to maintain the same IP addresses even if one provider fails, and gives you control over which provider handles specific traffic. Learn more about how this works in our guide on IP transit.
Organizations that operate as internet service providers, data centers, or cloud hosting companies need ASNs to manage their network infrastructure and peer with other networks.
Having your own ASN gives you granular control over how traffic enters and leaves your network. You can implement specific routing policies, optimize traffic paths, and make strategic peering decisions.
With your own ASN and IP address space, you're not locked into a single provider. You can switch providers without renumbering your entire infrastructure, which can be a massive operational headache.
If you want to establish direct peering relationships with other networks (rather than relying solely on your upstream provider's connections), you'll need an ASN to participate in these arrangements.
Getting an ASN isn't particularly difficult, but it does require meeting certain criteria and following a specific process. The exact steps depend on your geographic region, as different Regional Internet Registries (RIRs) oversee different parts of the world.
There are five RIRs that manage internet number resources globally:
You'll need to apply through the RIR that serves your geographic region.
Before applying for an ASN, you need to demonstrate a legitimate need. Generally, this means you must have a multi-homing plan where you'll be connecting to at least two different upstream providers or peers. Single-homed networks (connected to just one provider) typically don't qualify because they can use the provider's ASN.
You'll also generally need to have your own IP address space. While requirements vary by RIR, you typically need your own Provider Independent (PI) or Provider Aggregatable (PA) IP address allocation. Some RIRs allow you to apply for an ASN and IP addresses simultaneously.
Additionally, you'll need to submit a routing policy documenting your intended routing strategy and how you plan to use the ASN. Most RIRs require organizational membership, which comes with annual fees that vary by region and organization size.
Here's a general overview of what applying for an ASN looks like, though specific details vary by RIR.
First, register with your regional RIR and create an organizational account. You'll need to provide business registration documents and contact information.
Next, gather the required documentation, which typically includes your network diagram, peering arrangements or letters of intent from upstream providers, and your routing policy.
Complete the ASN request form through the RIR's portal. You'll need to explain your technical justification and demonstrate that you meet the requirements. The RIR will review your application to verify that you have a legitimate need for an ASN and that your technical plans are sound.
Once approved, you'll pay the registration fee and any applicable membership fees. Costs vary significantly by RIR, ranging from a few hundred to several thousand dollars annually. After payment, you'll be assigned an ASN from the available pool. The RIR will also help you register your ASN in the appropriate routing databases.
Getting the ASN is just the beginning. You'll need to configure BGP by setting up sessions with your upstream providers or peers. This involves configuring routers, establishing BGP neighbor relationships, and implementing your routing policy.
Create route objects in the Internet Routing Registry (IRR) to document which IP prefixes your ASN will announce. This helps other networks validate your routing announcements.
Keep your contact information up to date with the RIR, pay annual fees on time, and actively manage your routing policy as your network evolves. If you're new to BGP and autonomous systems, working with a network consultant or managed service provider can help you avoid costly mistakes during setup and operation.
You don't need to be huge to get an ASN. While major tech companies and ISPs certainly have ASNs, smaller organizations with legitimate multi-homing needs can obtain them too. There's no minimum size requirement, and it's not just for ISPs either. Content delivery networks, large enterprises, educational institutions, and even some hosting companies benefit from having their own ASNs.
One important thing to understand is that an ASN doesn't give you IP addresses automatically. ASNs and IP address allocations are separate (though related) resources. You typically need to apply for both, though some RIRs allow combined applications.
You can't technically buy an ASN in most regions, but you can transfer them between organizations under specific circumstances. Each RIR has its own transfer policies. Generally, the receiving organization still needs to demonstrate a legitimate technical need for the ASN.
Costs vary significantly by region and are typically structured as an initial registration fee plus annual maintenance fees. ARIN charges around $500 initially and $150-$500 annually depending on your organization size. RIPE NCC has different fee structures based on membership category. Always check your regional RIR's current fee schedule.
If you no longer need your ASN, you should return it to the RIR. Most RIRs have processes for voluntarily returning resources. If you stop paying annual fees without returning the ASN, the RIR may eventually reclaim it.
Yes, absolutely. Any organization with a legitimate technical need for multi-homing and independent routing control can apply for an ASN. This includes enterprises, content providers, data centers, and educational institutions.
An ASN gives you control over your network's presence on the internet. While not every organization needs one, those that do gain significant benefits in terms of reliability, routing control, and provider independence. The process of obtaining an ASN requires meeting technical requirements and working through your regional internet registry, but it's achievable for organizations of various sizes.
If you're considering getting an ASN, start by evaluating whether you truly need one, then familiarize yourself with your RIR's specific requirements and fee structure.
Thanks for reading! If you're looking for infrastructure to support your network, xTom provides enterprise-grade dedicated servers and colocation services.
For customers using our dedicated server or colocation offerings, we provide IPv4, IPv6, and ASN services as part of your hosting solution. We also facilitate IP address transfers in the APNIC region. Additionally, we offer IP transit services for organizations with their own ASNs.
For those not yet ready for dedicated infrastructure, V.PS offers scalable, production-ready NVMe-powered VPS hosting, and our shared hosting provides an easy entry point. Explore all our services to find what fits your needs.
Ready to discuss your infrastructure needs? Contact our team to explore the right solution for your projects.