Understanding IP Addresses, Subnets, and AS Numbers

What is an IPv4 Address?

IPv4, or Internet Protocol version 4, is the fourth version of the Internet Protocol (IP). It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. IPv4 uses a 32-bit address scheme allowing for a total of 2³² addresses (approximately 4.3 billion addresses).

Each IPv4 address is composed of four numbers separated by periods. Each number can be between 0 and 255. For example, 192.168.0.1 is an IPv4 address. The address is divided into two parts: the network part and the host part. The network part identifies the specific network on which a device resides, while the host part identifies the specific device on that network.

Subnetting in IPv4

Subnetting is the practice of dividing a network into two or more smaller networks. It helps improve routing efficiency, enhance security, and reduce the size of broadcast domains. Each subnet has its own unique identifier, which is included as part of the IP address.

Example: In the IP address 192.168.1.0/24, '192.168.1.0' is the network part, and '/24' indicates the subnet mask. The '/24' subnet mask means the first 24 bits are used for the network part, leaving the remaining 8 bits for host addresses within that network.

What is an IPv6 Address?

IPv6, or Internet Protocol version 6, is the most recent version of the Internet Protocol (IP), designed to address the limitations of IPv4, especially the exhaustion of IP addresses. IPv6 uses a 128-bit address scheme, allowing for a virtually unlimited number of unique IP addresses.

An IPv6 address is represented as eight groups of four hexadecimal digits, separated by colons. For example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334 is an IPv6 address. This expanded address space allows for better hierarchical address allocation, simplified network configuration, and improved security features.

Advantages of IPv6

• Large address space: IPv6 supports 2¹²⁸ addresses, enough to assign a unique address to every device on the planet and beyond.
• Improved security: IPv6 was designed with IPsec (Internet Protocol Security) in mind, providing confidentiality, authentication, and data integrity.
• Auto-configuration: IPv6 allows devices to configure themselves automatically when connected to an IPv6 network.
• Eliminates the need for NAT (Network Address Translation): With the vast number of available addresses, each device can have a unique global IP address.

How to Become a Holder of IP Subnets

Becoming a holder of IP subnets involves obtaining IP address space from a regional internet registry (RIR). There are five RIRs worldwide:

• ARIN (American Registry for Internet Numbers) – North America
• RIPE NCC (Réseaux IP Européens Network Coordination Centre) – Europe, Middle East, and parts of Central Asia
• APNIC (Asia-Pacific Network Information Centre) – Asia-Pacific region
• LACNIC (Latin America and Caribbean Network Information Centre) – Latin America and the Caribbean
• AFRINIC (African Network Information Centre) – Africa

To obtain IP address space, you must become a member of the appropriate RIR and demonstrate a justified need for the IP addresses. This process typically involves:

1. Submitting an application detailing your organization's need for IP addresses.
2. Providing network plans and documentation to justify your request.
3. Paying membership and allocation fees to the RIR.

How to Get Your Own AS Number

An Autonomous System (AS) is a collection of IP networks and routers under the control of a single organization that presents a common routing policy to the internet. An AS is identified by an Autonomous System Number (ASN).

To obtain an ASN, you must meet certain criteria, such as:

• Your network must connect to at least two different autonomous systems (multi-homed).
• You must have a unique routing policy distinct from your upstream providers.

The process for obtaining an ASN involves:

1. Applying to your regional internet registry (RIR).
2. Providing detailed network information and justifications.
3. Paying applicable fees.

Cost of Handling an AS Number

The cost of obtaining and maintaining an ASN varies by RIR and can include membership fees, application fees, and annual renewal fees. For example:

• ARIN charges an annual fee based on the number of resources (IPv4, IPv6, and ASN) held by the organization.
• RIPE NCC has a one-time sign-up fee and annual membership fees based on the size of the organization.
• APNIC, LACNIC, and AFRINIC have similar fee structures with varying amounts.

In some cases, you may be able to get sponsorship from an existing member or organization that can justify your need for an ASN.

Can You Get an ASN for Free or Sponsored?

While it is uncommon to get an ASN for free, there are scenarios where you might receive sponsorship. Some organizations, especially educational or non-profit entities, may find sponsors willing to cover the costs of obtaining and maintaining an ASN. Additionally, some internet service providers (ISPs) or network operators may offer sponsorship or assistance to their customers who need an ASN.

If you're considering this route, it is essential to clearly articulate your needs, the benefits to the sponsor, and how you plan to manage and use the ASN responsibly.

Conclusion

Understanding the intricacies of IPv4 and IPv6 addresses, subnets, and AS numbers is crucial for network administrators and anyone involved in internet infrastructure. IPv4 addresses are still widely used, but the transition to IPv6 is essential due to the limited address space of IPv4. Subnetting helps manage IP addresses efficiently within a network, and obtaining an ASN allows organizations to have a unique presence on the internet with their routing policies.

While becoming a holder of IP subnets and obtaining an ASN involves specific processes and costs, the benefits of having control over your IP address space and routing policies are significant. Whether you are a small organization or a large enterprise, understanding and leveraging these elements can enhance your network's efficiency, security, and scalability.