RFC 4893 defines BGP support for four-octet AS number space for handling AS_PATH attributes and "My ASN" value in BGP OPEN messages. Foue-Octet AS specific Extended Community attribute formats are defined in draft-rekhter-as4octet-ext-community-03.txt. However, an implementation compliant to RFC 4893 does not necessarily provide support for 4-Octet Route-distinguisher, Route-target or Site-of- origin in the BGP-MPLS-VPN. Thus BGP capability exchange for extended AS number attribute does not cover the BGP-MPLS-VPN AS4- specific route-attributes and route-distinguishers. This document proposes an optional BGP capability exchange between the Provider Edge (PE) routers in order to communicate the intention of handling 4-Octet or 2-Octet exteneded AS-specific Route-targets or Site-of- Origins or being able to handle and inteprete the 4-Octet route- distinguishers correctly. This capability parameter will be part of OPEN message during the BGP session initiation.