RFC 4893 · PROPOSED STANDARD · 2007
SUN · 14 JUN 2026
BGP Support for Four-octet AS Number Space
Overview
RFC 4893, “BGP Support for Four-octet AS Number Space”, is a Proposed Standard document published in May 2007 by Q. Vohra, E. Chen. It has been obsoleted by RFC 6793 — refer to the newer document for the authoritative version. The canonical text is published by the RFC Editor.
Abstract
Currently the Autonomous System (AS) number is encoded as a two-octet entity in BGP. This document describes extensions to BGP to carry the Autonomous System number as a four-octet entity. [STANDARDS-TRACK]
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
Read this RFC
The canonical text of RFC 4893 is hosted at rfc-editor.org. Available in TXT,HTML.
Relationships to other RFCs
Other RFCs from 2007
- RFC 4892 Requirements for a Mechanism Identifying a Name Server Instance
- RFC 4894 Use of Hash Algorithms in Internet Key Exchange and IPsec
- RFC 4891 Using IPsec to Secure IPv6-in-IPv4 Tunnels
- RFC 4895 Authenticated Chunks for the Stream Control Transmission Protocol
- RFC 4890 Recommendations for Filtering ICMPv6 Messages in Firewalls
- RFC 4896 Signaling Compression Corrections and Clarifications
- RFC 4889 Network Mobility Route Optimization Solution Space Analysis
- RFC 4897 Handling Normative References to Standards-Track Documents