| 6.2 |  | Dynamic Routing Overview |
| 6.2.2 |  | Autonomous systems |

| An autonomous system (AS) is a collection of networks under a common administration sharing a common routing strategy. To the outside world, an AS is viewed as a single entity. The AS may be run by one or more operators while presenting a consistent view of routing to the external world. The American Registry of Internet Numbers (ARIN), a service provider, or an administrator assigns an identifying number to each AS. This autonomous system number is a 16 bit number. Routing protocols, such as Cisco’s IGRP, require assignment of a unique, autonomous system number.
| Web Links Autonomous System http://searchnetworking.techtarget.com/ sDefinition/ 0,,sid7_gci213662,00.html