What is Autonomous System (AS)?

Autonomous System (AS): Here, we are going to learn about the autonomous system, categories, etc.
Submitted by Anushree Goswami, on January 09, 2021

AS: Autonomous System

AS is an abbreviation of "Autonomous System". It is a compilation of linked associated Internet Protocol (IP) routing prefixes underneath the directive of one or more network operators as a representative of a distinct directorial entity or domain that presents a widespread, evidently described routing policy to the internet.

  • In the beginning, the description needed management by a particular entity, normally an Internet service provider (ISP) or an extremely huge association or business with autonomous associations to a range of networks, that remained to a distinct and described routing policy, as formerly described in RFC 1771.
  • The recently developed description in RFC 1930 appeared into use for the reason that various organizations can operate Border Gateway Protocol (BGP), by using private AS numbers to an ISP that attaches all those organizations to the internet. Even if there may be a range of self-directed systems supported by the ISP, the internet simply perceives the routing policy of the ISP. That ISP required being having an authoritatively registered autonomous system number (ASN).


Autonomous systems can be classified into four categories; the entire depends on their connectivity and working policy, which comprise:

  • Multihomed:
    1. It is an AS that upholds associations to more than one other AS. This enables the AS to stay associated to the internet in the result of an absolute breakdown of one of their connections.
    2. On the other hand, contrasting a transit AS, this category of AS would not permit traffic from one AS to overtake through on its system to an additional AS.
  • Stub:
    1. It is an AS that is associated to merely one further AS. This may be an evident squander of an AS number if the network's routing policy is similar as it’s upstream AS's.
    2. On the other hand, the stub AS may have the exchange of data directly among Internet service providers with additional autonomous systems that are not imitated in public route-view servers. Particular examples comprise confidential interconnections in the economic and transportation segments.
  • Transit:
    1. It is an AS that makes available associations through itself to additional networks. It signifies network A can make use of network B, the transit AS, to connect to network C.
    2. If one AS is an ISP for an additional, then it is regarded as a transit AS.
  • Internet Exchange Point (IX or IXP):
    1. A substantial infrastructure through which ISPs or content delivery networks (CDNs) exchange internet traffic among their networks (autonomous systems).
    2. IXP ASNs are generally crystal clear.

Reference: Autonomous system (Internet)

Algo tagged in: Dictionary – 'A'

Comments and Discussions!

Copyright © 2023 www.includehelp.com. All rights reserved.