Hey everyone, Geane here. Today we’re going to talk about ASN (Autonomous System Number) and the benefits it offers you.

What is ASN?

An Autonomous System Number (ASN) is a group of IP address networks managed by one or more network operators that have a clear and unique routing policy. Each Autonomous System (AS) has an associated number that is used to identify the Autonomous System when exchanging external routing information. External routing protocols, such as BGP, use the ASN to exchange routing information with other ASNs.

ASNs come in two formats: 2-byte and 4-byte.

– A 2-byte ASN is a 16-bit number. This format provides 65,536 ASNs (0 through 65,535). Of these ASNs, the Internet Assigned Numbers Authority (IANA) has reserved 1,023 (64,512 through 65,534) for private use.

– A 4-byte ASN is a 32-bit number. This format provides 2³² or 4,294,967,296 ASNs (0 to 4,294,967,295). IANA has reserved a block of 94,967,295 ASNs (4,200,000,000 to 4,294,967,294) for private use.

To obtain an autonomous system, you must request an Autonomous System Number (ASN) from the Regional Internet Registry (RIR) corresponding to the region where your organization is located. In Brazil, the responsible organization is LACNIC. In addition, you must configure the network devices in accordance with the routing policies defined by the organization, which can be found on the institutions’ websites.

Check out our article on “How to Request an ASN from Your Provider?”

There are currently five RIRs in operation:

1 – American Registry for Internet Numbers (ARIN): North America and parts of the Caribbean;

2 – Réseaux IP Européens Network Coordination Centre (RIPE NCC): Europe, the Middle East, and Central Asia;

3 – Asia-Pacific Network Information Centre (APNIC): Asia and the Pacific;

4 – Latin American and Caribbean Internet Addresses Registry (LACNIC): Latin America and parts of the Caribbean;

5 – African Network Information Centre (AfriNIC): Africa.

Did you know that it’s not just service providers, telecommunications companies, and ISPs that must be Autonomous Systems? Other types of companies also need to use them, such as banks, universities, insurance companies, production companies, news portals, and large corporations—since internet access is critical to their core business, and an ASN can ensure that these services are always available and secure.

When an organization becomes an AS, it is assigned an ASN (Autonomous System Number)—a number that identifies the set of IP addresses owned by that organization—which is crucial for identifying the systems and enabling the exchange of information and routes between them.

What are the benefits of having an ASN?

1. Unique Internet Identifier: An ASN is a unique number assigned to an organization or provider. It serves as a unique identifier on the Internet and is used to distinguish that organization’s network from other networks on the global Internet. This is crucial for ensuring that traffic is correctly routed to your network.
2. Autonomous Routing: An ASN allows an organization to operate its own autonomous routing. This means that the organization has full control over how its traffic is routed across the Internet. This is especially important for Internet service providers, as it allows them to determine the most efficient routes for their customers’ traffic.
3. Better Traffic Control: With an ASN, an organization can make specific decisions about how traffic is routed on its network. This can be used to optimize performance, prevent congestion, and ensure that traffic is distributed efficiently.
4. BGP Implementation: BGP (Border Gateway Protocol) is a routing protocol used on the Internet to exchange routing information between autonomous systems. Having an ASN is essential for implementing BGP and actively participating in Internet routing.
5. Multi-homing: If an organization wants to connect to multiple Internet service providers for redundancy and high availability, an ASN is required. This allows the organization to advertise its own IP routes and dynamically choose the best route based on real-time network conditions.
6. Scalability: As an organization grows and expands its online presence, having an ASN becomes essential for managing the complexity of routing. This allows the organization to adjust its routing policies and grow in a scalable manner.
7. Security: Having control over your network’s routing through an ASN also offers security benefits. This allows your organization to implement specific security policies, such as filtering unwanted traffic or preventing DDoS attacks.

Requesting and obtaining an ASN is essential for an organization—especially an Internet service provider—to have full control over its network infrastructure, optimize performance, improve redundancy and security, and actively participate in global Internet routing.

We offer comprehensive support and consulting services for requesting and implementing ASN in your network. Please contact us to find out how we can help you.