3. AS_CONFED Segment Type Extension

Currently, BGP specifies that the AS_PATH attribute is a well-known mandatory attribute that is composed of a sequence of AS path segments. Each AS path segment is represented by a triple <path segment type, path segment length, path segment value>.

In [BGP-4], the path segment type is a 1-octet field with the two following values defined:

Value 1: AS_SET ordered set of autonomous systems that a route in the UPDATE message has traversed

Value 2: AS_SEQUENCE ordered set of autonomous systems that a route in the UPDATE message has traversed

This document specifies two additional segment types:

Value 3: AS_CONFED_SEQUENCE ordered set of Member Autonomous Systems in the local confederation that the UPDATE message has traversed

Value 4: AS_CONFED_SET unordered set of Member Autonomous Systems in the local confederation that the UPDATE message has traversed