HPE HPE Path Attributes in the BGP-4 protocol (RFC 4271) carry data associated with BGP routes. Many of the Path Attributes carried in BGP are intended for limited scope deployment. However, the extension mechanism defined by BGP that carries these attributes often carries them farther than necessary, sometimes with unfortunate results. This document defines a mechanism using BGP Capabilities (RFC 5492) that permits eBGP speakers to determine what Path Attributes should be permitted to cross external BGP routing boundaries.