Explaining 4-Byte Autonomous System (AS) ASPLAIN and ASDOT Notation for Cisco IOS

This paper provides insight into the two leading notations for devices supporting 4-Byte Autonomous Systems technology known as ASPLAIN and ASDOT. The ASPLAIN notation is the Cisco IOS default notation. However, Cisco IOS will support ASDOT via a configuration option. Switching between representation formats does not automatically change the AS-PATH policy rules configured on a Cisco router, and hence if policy rules are on the router configured, they will have to be updated through a manual process.