Home>

Knowledge Hub>

Autonomous system and AS numbers (ASN)

What is an autonomous system and what are AS Numbers (ASN)?

The term Autonomous Systems (AS) usually refers to larger IP network associations that are managed by a single routing policy. For identification purposes, a unique Autonomous System Number (ASN) is assigned to each AS. The individual Autonomous Systems together make up the Internet. The division of the World Wide Web into individual segments allows better scalability while resource consumption remains low.

Myra Services on this topic: Certified protection against DDoS attacks for data centers and IT infrastructures with Myra Cloud Scrubbing

At one look

  1. 01. Autonomous Systems & ASNs: Definition
    1. 02. Who assigns the ASN?
      1. 03. Autonomous Systems and AS numbers: What you need to know

        01

        Autonomous Systems & ASNs: Definition

        Autonomous Systems (AS) can be understood as a group of routers and networks that are managed as an administrative entity via a single routing policy. The Internet is composed of these same large network groups operated by individual organizations – most commonly Internet Service Providers (ISPs), technology companies, universities or government agencies. Each AS controls its own IP address space, which includes all IPs managed within the AS. The IP address space is listed in the routing policy for the AS. It also includes the other network groups connected to the AS. This information is required for the successful routing of data packets between different AS networks.

        For the external communication between routers in different network groups, each AS is additionally assigned a unique number (16-bit, 32-bit), the so-called AS Number (ASN). A distinction is made between public and private ASNs, whereby public ASNs are designated for data transfer across the Internet, while private ASNs are limited to systems that are only connected to a single provider. Data is routed between different Autonomous Systems using the Border Gateway Protocol (BGP).

        Code on a screen

        02

        Who assigns the ASN?

        The Internet Assigned Numbers Authority (IANA) is responsible for the allocation of ASNs. The IANA delegates the actual allocation to the Regional Internet Registries (RIR), which are responsible for the allocation in North America (ARIN), Europe, Middle East and Central Asia (RIPE NCC), Asia-Pacific (APNIC), Latin America, the Caribbean (LACNIC) and Africa (AfriNIC).

        Person on laptop and writing code with a cell phone in hand

        03

        Autonomous Systems and AS numbers: What you need to know

        Autonomous Systems (AS) are larger network groups that are managed by means of a single routing policy. Autonomous Systems are typically operated by larger organizations, network operators (ISPs), universities or government agencies. The Internet is composed of the individual AS networks. To identify the network groups, each AS has a unique ASN (AS Number). Depending on whether the AS is connected to several other Autonomous Systems or only to individual network groups, a distinction is made here between public and private ASNs. The connection between the Autonomous Systems for data routing is established using the Border Gateway Protocol (BGP).

        Myra Security operates an independent AS in order to provide our customers with the best possible quality of service. This solution ensures the independent operation of our Security-as-a-Service platform.

        © Myra Security GmbH 2024, all rights reserved

        Responsible DisclosureLegal noticePrivacy policyTerms and Conditions