a global question is when using Inter AS VPN , and i am using Private AS , and will be connecting to another provider with Public AS.
do i need to register a public AS alos for this scenario , or i can run the service with my own private AS without having to change it.
taking into consideration that will most probably use VRF-VRF connection as based on RFC 4364
The AS path on prefixes received from the other AS via BGP on the VRF interface will definitely be propagated via VPNv4 as well as all the other transitive attributes.
Hope this helps,