Autonomous system

As explained in Acing the CCNA Exam: Volume 1 Fundamentals and Protocols

An autonomous system is a collection of networks and routers under a common administrative control that participates in interdomain routing.

An autonomous system (AS) is a network under one organization’s control. Interior Gateway Protocols exchange routes within an AS, while Exterior Gateway Protocols exchange routes between ASes. section 17.2

This boundary explains how routing scales: internal routers use an IGP, while organizations and Internet service providers use an EGP. BGP represents paths as sequences of ASes rather than individual routers. section 17.2 section 17.2.2

Enterprise-to-enterprise path

A packet leaving Enterprise A can cross ISP A and ISP B before reaching Enterprise B. BGP communicates this inter-AS path, while each organization uses an IGP internally. section 17.2.2

Figure 17.5 IGPs are used to exchange routing information with routers in the same AS (connected with solid lines). EGPs are used to exchange routing information with routers in a different AS (connected with dotted lines).

Compare solid intra-AS routing links with dotted inter-AS links. section 17.2

How Acing the CCNA Exam: Volume 1 Fundamentals and Protocols covers it

How deep it goes

Defines AS boundaries and contrasts router-to-router internal routing with AS-to-AS BGP logic, but does not explain BGP configuration.

Examples

Uses enterprise networks, ISPs, and a route crossing ISP A and ISP B to illustrate interdomain paths.

What it assumes

Introduces the AS, IGP, and EGP distinction while assuming familiarity with networks, routers, and routing information.

What you can do after

Evaluate whether a routing relationship is internal to an AS or external between ASes.

How it connects

Connects autonomous systems to dynamic routing, IGPs, EGPs, BGP, and path-vector algorithms.

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Also explained in

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  Delivering Machine Learning Projects: From design to deploymentAn autonomous system is a system that operates independently for extended periods without human intervention and manages its own operational episodes.

Compare how 2 books explain autonomous system →

Related concepts

• data streamproduces · A data stream is an ordered sequence of data items or events made available incrementally for consumption or processing.
• assistive systemcontrasts with · An assistive system is a human-facing computational system that provides information, advice, predictions, or recommendations without controlling the resulting decisions.
• delegative systemcontrasts with · A delegative system is a system that makes decisions on a user's behalf while providing the human with timely mechanisms to review, correct, or override those decisions.
• nonfunctional requirementuses · A nonfunctional requirement specifies a quality attribute, constraint, or operating condition that a system must satisfy beyond the particular functions it performs.
• automationcontrasts with · Automation is the execution of tasks or processes by machines or software with reduced direct human intervention.
• exterior gateway protocolused by · An exterior gateway protocol is a routing protocol that exchanges routing information between different autonomous systems.

This explainer was generated by Manning's knowledge graph from the text of Acing the CCNA Exam: Volume 1 Fundamentals and Protocols. The section links point to the parts of the book it draws on.