In the diagram below, an end-to-end transport tunnel needs to be established between PE1 and...

To establish an end-to-end transport tunnel using MP-BGP between PE1 and PE2, the following items are required:

MP-BGP Address Families: MP-BGP address families such as label-ipv4 or label-ipv6 need to be supported on each of the edge routers (PE routers) to handle labeled routes.

Transport Tunnels Between Regions: Tunnels using protocols like RSVP, LDP, or segment routing need to be established between regions to ensure end-to-end connectivity.

Transport Tunnels Within Each Region: Similarly, tunnels using RSVP, LDP, or segment routing need to be established within each region to maintain connectivity.

However, each PE router advertising an IP address as a labeled BGP route is not required for identifying the tunnel endpoint. The tunnel endpoints are typically identified by the transport tunnels established using the above protocols (RSVP, LDP, or segment routing).

ReferencesNokia Border Gateway Protocol Fundamentals, Chapters on MP-BGP and BGP/MPLS VPNs.