4-byte AS Number Specifications

Regional Internet Registries (RIRs), including the RIPE NCC (Network Coordination Centre), have warned that routers and network management software should be upgraded ahead of the increased distribution of four-byte (also known as 32-bit) Autonomous System (AS) numbers.

APNIC is warning organisations they need to ensure their network infrastructure is compatible with the new 32-bit AS routing numbers, to be introduced next January

On 13 June 2008, the Chair of the Address Supporting Organization Address Council forwarded a Proposed Global Policy for Autonomous System Numbers, ASNs, for ratification by the ICANN Board. Essentially, the proposal defines timelines and allocation principles for a transition from 2-byte to 4-byte ASNs.

What are Autonomous System Numbers (ASNs), and what role do they play in the technology of the Internet? This article explores the role of ASNs exploring how the AS space is structured and how AS numbers are used in the interdomain routing. Also has analysis of the consumption rate and has a brief overview of Internet routing architecture.