The statement is false because the eBGP session between a Carrier Supporting Carrier Provider Edge (CSC-PE) and a CSC Customer Edge (CSC-CE) does not exchange VPN-IPv4 routes. Instead, it exchanges standard IPv4 routes with an associated MPLS label (BGP-LU). The CSC-CE advertises its internal VPRN routes as labeled IPv4 prefixes to the CSC-PE. The CSC-PE then converts these labeled IPv4 routes into VPN-IPv4 routes for transport across the backbone provider's network. The correct configuration on the CSC-CE involves enabling label advertisement under the family ipv4 context, not using a family vpn-ipv4 context for this specific eBGP session.

B. This is a valid and often necessary configuration. If the customer carrier uses the same AS number at multiple sites, the BGP ASPATH loop detection mechanism on the CSC-PE would discard routes, requiring loop-detect off to be enabled.

C. This is the specific command required on a Nokia 7750 SR to enable CSC functionality for a VPRN service. It allows the VPRN to accept labeled IPv4 routes from the CSC-CE router.

D. This accurately describes the standard mechanism for route exchange between PE routers in an MPLS VPN backbone. The CSC-PEs (PE1 and PE2) use MP-iBGP with the family vpn-ipv4 address family to exchange the customer carrier's routes.

1. Nokia 7450 ESS, 7750 SR, 7950 XRS, and VSR Layer 3 Services Guide, Release 21.10.R1, Document Number: 3HE 17179 AAAD TQZZA.

Section: Carrier Supporting Carrier VPRN: "The CSC-PE router receives labeled IPv4 routes from the CSC-CE router and converts them into VPN-IPv4 routes. The VPN-IPv4 routes are then advertised over the backbone carrier’s network to the other CSC-PE routers." This confirms that the CSC-PE to CSC-CE link carries labeled IPv4, not VPN-IPv4, making statement A false.

Section: Carrier Supporting Carrier VPRN: "To configure a VPRN service as a CSC VPRN, the carrier-carrier-vpn command must be configured in the VPRN service." This confirms statement C is correct.

Section: Carrier Supporting Carrier VPRN: "To avoid BGP discarding routes with the same AS in the path, the loop-detect command can be configured on the CSC-PE to disable loop detection." This confirms statement B is correct.

The overall architecture described in the guide, consistent with RFC 4364, validates that CSC-PEs exchange routes among themselves using MP-iBGP with the vpn-ipv4 address family, confirming statement D.