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AS (autonomous system)

An Autonomous System (AS) is a group of IP networks operated by one or more network operators that has a single, clearly defined routing policy. Each AS is identified by a unique Autonomous System Number (ASN), and is used for exchanging routing information using the Border Gateway Protocol (BGP)[5][7].


Examples of Autonomous Systems (AS) on the internet include:


  1. Tier 1 Internet Service Providers (ISPs): These are the largest ASes, maintaining massive network infrastructures that form the backbone of the internet. They interconnect with each other on a non-commercial basis, allowing packets to pass freely between them. Examples include AT&T (AS7018), Verizon (AS701), and Level 3 Communications (AS3356).
  2. Tier 2 ISPs: These ISPs contract with Tier 1 ISPs for access to the internet backbone. They may also peer with other Tier 2 ISPs to exchange traffic directly. Examples include Sprint (AS1239) and Cogent Communications (AS174).
  3. Tier 3 ISPs: These are local ISPs that typically purchase internet access from Tier 2 ISPs. They serve end users and businesses with internet connectivity. An example would be a local internet service provider in a city or town.
  4. Content Delivery Networks (CDNs): CDNs use ASes to distribute content more efficiently across the internet. By caching content at strategic locations around the world, they can deliver it more quickly to end users. Examples include Akamai Technologies (AS20940) and Cloudflare (AS13335).
  5. Large Enterprises and Corporations: Some large companies operate their own ASes to control routing within their networks and to exchange routing information with ISPs. This allows them greater control over their internet traffic and policies. Examples include Google (AS15169) and Microsoft (AS8075).
  6. Universities and Research Institutions: Many universities and research institutions operate their own ASes for greater control over their network infrastructure and to facilitate academic and research-related internet traffic. Examples include the Massachusetts Institute of Technology (AS3) and Stanford University (AS32).
  7. Internet Exchange Points (IXPs): While not a single AS, IXPs are physical infrastructure locations where ISPs and CDNs exchange internet traffic between their networks. Many ASes connect to IXPs to improve internet connectivity and performance. Examples of IXPs include the Amsterdam Internet Exchange (AMS-IX) and the London Internet Exchange (LINX).
  8. Edge Networks: This emerging category of ASes represents companies like Vapor IO (AS5670), which provides the edge network for Zero Gap AI.



Citations:

[1] https://www.cloudflare.com/learning/security/glossary/what-is-bgp/

[2] https://www.merriam-webster.com/dictionary/as

[3] https://www.fortinet.com/resources/cyberglossary/bgp-border-gateway-protocol

[4] https://www.dictionary.com/browse/as

[5] https://aws.amazon.com/what-is/border-gateway-protocol/

[6] https://dictionary.cambridge.org/us/dictionary/english/as

[7] https://www.techtarget.com/searchnetworking/definition/BGP-Border-Gateway-Protocol

[8] https://www.britannica.com/dictionary/as

[9] https://en.wikipedia.org/wiki/Border_Gateway_Protocol

[10] https://www.collinsdictionary.com/us/dictionary/english/as

[11] https://www.kentik.com/kentipedia/what-is-bgp-border-gateway-protocol/

[12] https://dictionary.cambridge.org/us/grammar/british-grammar/as

[13] https://www.imperva.com/learn/ddos/border-gateway-protocol-bgp/

[14] https://www.vocabulary.com/dictionary/as

[15] https://www.geeksforgeeks.org/border-gateway-protocol-bgp/

[16] https://www.yourdictionary.com/as

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