BGP-4 typically carries network reachability information between routers across IPv4 networks. If it's routing betwen IPv6 networks it uses the multiprotocol extensions for BGP-4. But the assumption is that the network that BGP rides over is an IPv4 network. What if the network BGP rides over is IPv6? How are the BGP attributes set up in this case? In particular the BGP ID in the Open Message's, and the Withdrawn Routes Prefix in the Update Message. I can figure out most of the other IP related attributes.