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Autonomous system (Internet)

An autonomous system (AS) is a collection of connected Internet Protocol (IP) routing prefixes under the control of one or more network operators on behalf of a single administrative entity or domain, that presents a common and clearly defined routing policy to the Internet.

Version
v1 · 2026-09-28 · History
Domain-specific #
8090
Domain group
Applied Sciences & Engineering
Origin domain
Computer Science & Software Engineering
Subdomains
Computer Networking, Internet Routing → Computer Science & Software Engineering

Core Idea

Autonomous system (Internet) is treated here as the recurring computerscienceandinformation identity summarized by this source-grounded definition: An autonomous system (AS) is a collection of connected Internet Protocol (IP) routing prefixes under the control of one or more network operators on behalf of a single administrative entity or domain, that presents a common and clearly defined routing policy to the Internet. An autonomous system (AS) is a collection of connected Internet Protocol (IP) routing prefixes under the control of one or more network operators on behalf of a single administrative entity or domain, that presents a.

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The Internet Neighborhood

The internet is made of lots of smaller networks joined together. An autonomous system is one of those networks run by one group, like one company, which has its own clear rules for how messages travel in and out. It even gets its own special number so the other networks know who it is.

One Network, One Set of Rules

The internet is really a network of networks. An autonomous system, or AS, is a group of connected network addresses run on behalf of one organization — like an internet provider or a large company — that tells the rest of the internet one clear set of rules for how to reach it. Each AS gets an autonomous system number, which networks use when they share routes with each other through a system called BGP. These numbers are handed out by big registries around the world. Some numbers are kept for private use only and should never be shown to the whole internet.

Single-Policy Routing Domain

An autonomous system (AS) is a collection of connected IP routing prefixes (blocks of internet addresses) controlled by one or more network operators on behalf of a single administrative entity, presenting one common, clearly defined routing policy to the internet. Each AS has an autonomous system number (ASN) used by the Border Gateway Protocol (BGP), the protocol networks use to exchange routes. IANA gives blocks of ASNs to regional internet registries, which assign them to local registries and organizations; IANA also reserves some ASNs for private use that should not be announced globally. The original definition required control by a single entity with a single policy, but in 1996 it was broadened because several organizations can run BGP with private ASNs through one ISP that connects them all. What matters is the single administrative domain and unified routing policy, not just having a network.

 

An autonomous system (AS) is a collection of connected IP routing prefixes under the control of one or more network operators acting on behalf of a single administrative entity or domain, presenting a common and clearly defined routing policy to the Internet. Each AS is assigned an autonomous system number (ASN) for use in Border Gateway Protocol (BGP) routing. ASNs are allocated to local Internet registries and end-user organizations by regional Internet registries (RIRs), which receive blocks from the Internet Assigned Numbers Authority (IANA); IANA also maintains a registry of private-use ASNs that should not be announced to the global Internet. The original definition required control by a single entity, typically an ISP or a large organization with independent connections to multiple networks, following one routing policy. In March 1996 the newer definition came into use, reflecting that multiple organizations can run BGP with private ASNs to an ISP that connects them all to the Internet. A positive case must preserve the core: connected prefixes, single administrative domain, and a unified externally presented routing policy; a network name, an ASN alone, or a familiar example does not suffice.

Scope of Application

  • Assignment. Entities wishing to receive an ASN must complete the application process of their RIR, LIR or upstream service provider and be approved before being assigned an ASN.

  • Types. This allows the AS to remain connected to the Internet in the event of a complete failure of one of their connections.

  • AS-SET. AS-SETs are often used to simplify management of published routing policies.

  • Documented setting. The first and last ASNs of the original 16-bit integers (0 and 65,535) and the last ASN of the 32-bit numbers (4,294,967,295) are reserved and should not.

  • Assignment. ASNs are assigned in blocks by the Internet Assigned Numbers Authority (IANA) to regional Internet registries (RIRs).

Clarity

A clear use of Autonomous system (Internet) names the carrier, the operative relation, and the conditions under which the source treats the identity as present. The minimal definition is An autonomous system (AS) is a collection of connected Internet Protocol (IP) routing prefixes under the control of one or more network operators on behalf of a single administrative entity or domain, that presents a common and clearly defined routing policy.

Manages Complexity

Autonomous system (Internet) compresses multiple computerscienceandinformation details into a stable diagnostic relation. The source shows both the central mechanism—the appropriate RIR then assigns ASNs to entities within its designated area from the block assigned by IANA.—and the practical consequence—internet exchange point (IX or IXP): A physical infrastructure through which different networks (autonomous systems), typically Internet service providers (ISPs) and content delivery networks (CDNs), exchange Internet traffic.

Abstract Reasoning

  1. Type the carrier. Identify the computerscienceandinformation entities to which the claim applies.
  2. State the relation. Use the source-grounded identity: An autonomous system (AS) is a collection of connected Internet Protocol (IP) routing prefixes under the control of one or more network operators on behalf of a single administrative entity or domain, that presents a common and clearly defined routing policy to the Internet.
  3. Check operation and conditions.

Knowledge Transfer

Within the home domain. Knowledge about Autonomous system (Internet) transfers literally when a new case preserves the same carrier type, relation, and recognition test. Entities wishing to receive an ASN must complete the application process of their RIR, LIR or upstream service provider and be approved before being assigned an ASN. This allows the AS to remain connected to the Internet in the event of a complete failure of one of their connections. Beyond the home domain. No canonical parent is asserted for Autonomous system (Internet).

Relationships to Other Abstractions

Local relationship map for Autonomous system (Internet)Parents appear above the current abstraction, mutual partners to the right, and children below. Node labels state whether each abstraction is prime or domain-specific; colors identify relation types.Autonomoussystem (Internet)DOMAINDomain-specific abstraction: Routing — presupposesRoutingDOMAIN

Current abstraction Autonomous system (Internet) Domain-specific

Parents (1) — more general patterns this builds on

  • Autonomous system (Internet) presupposes Routing Domain-specific

    An Internet autonomous system is defined by the routing prefixes and common routing policy it presents; without routing the AS identity disappears.

Hierarchy path (1) — routes to 1 parentless root

Neighborhood in Abstraction Space

Autonomous system (Internet) sits in a sparse region of the domain-specific corpus (72nd percentile for distinctiveness): few abstractions share its structure, so a faithful description tends to retrieve it precisely.

Family — Geological & Geographic Interpretation (8 abstractions)

Nearest neighbors

Computed from structural-signature embeddings · 2026-10-08