Autonomous system definition
An autonomous system is a collection of IP networks and routers under the control of one entity, typically an internet service provider (ISP), a large business, or an educational institution that presents a standard routing policy to the internet. A unique number identifies each AS, the autonomous system number (ASN), used in routing data across the internet.
Autonomous system examples
- Major ISPs: Large internet service providers like AT&T and Comcast each have their own AS.
- Large businesses: Multinational companies with substantial network infrastructure may have their own AS.
- Universities: Large educational institutions with significant network needs, like the University of California, Berkeley, might maintain an AS.
Understanding autonomous systems
- An AS allows for the efficient routing of internet traffic within its network, reducing dependence on external routers.
- Autonomous systems enable the use of the Border Gateway Protocol (BGP) to exchange routing information between routers in different ASes.
- Remember that while an AS aids in routing internet traffic, it also plays a part in internet security issues like BGP hijacking.