BGP/MPLS IP VPNs can only use LDP to construct public network tunnels.

The statement is false because BGP/MPLS IP VPNs can use multiple protocols to establish the public network tunnels (Label Switched Paths - LSPs) that carry VPN traffic across the provider's core network. While the Label Distribution Protocol (LDP) is a common and straightforward method that works in conjunction with an Interior Gateway Protocol (IGP), it is not the only option. Resource Reservation Protocol - Traffic Engineering (RSVP-TE) is another widely used protocol for this purpose. RSVP-TE provides advanced traffic engineering capabilities, such as explicit path routing and bandwidth reservation, which are not available with LDP. Therefore, a service provider can choose the tunneling protocol based on their specific network requirements, such as the need for traffic engineering.

The statement claims exclusivity ("only use LDP"), which is factually incorrect. The architecture of BGP/MPLS IP VPNs decouples the service layer (VPN route distribution via MP-BGP) from the transport layer (the tunnel across the core). This allows for flexibility in the transport layer, where protocols like RSVP-TE and, more recently, Segment Routing (SR-MPLS) can be used in addition to LDP.

1. Official Vendor Documentation (Huawei): In the Huawei HedEx documentation for VRP (Versatile Routing Platform), the configuration guides for MPLS L3VPN explicitly detail the creation and application of tunnel policies. These policies allow an administrator to select the type of tunnel to be used for the public network. The documentation shows that options include LDP LSP, RSVP-TE LSP, and others.

Source: Huawei NE40E-X8 V800R010C10SPC500 Configuration Guide - MPLS > MPLS L3VPN Configuration > Configuring a Tunnel Policy. This section typically states: "A tunnel policy can be configured to determine the type of tunnels used for VPN route iteration. The tunnel types include LDP LSPs, RSVP-TE LSPs, and CR-LSPs."

2. Official Vendor Documentation (Huawei): Huawei's official training materials for the HCIP-Datacom-Advanced Routing & Switching Technology certification (which covers the topics in H12-831 V1) explain the different MPLS tunneling technologies.

Source: HCIP-Datacom-Advanced Routing & Switching Technology V1.0 Training Material, Chapter on "MPLS L3VPN". The material describes how VPN traffic is forwarded over the public network using tunnels and explicitly mentions both LDP and MPLS TE (RSVP-TE) as mechanisms for establishing these tunnels.

3. Peer-reviewed Academic Publications / Foundational Standards (IETF): The foundational standard for BGP/MPLS IP VPNs does not mandate a specific tunneling protocol. It describes the need for a "tunnel" across the provider backbone but leaves the implementation of that tunnel open.

Source: IETF RFC 4364, "BGP/MPLS IP Virtual Private Networks (VPNs)", Section 8, "Forwarding". This section describes the packet forwarding process which involves pushing a label that directs the packet across the backbone to the egress PE. It does not restrict the method of establishing the path for this label. The existence of a separate standard, RFC 3209 ("RSVP-TE: Extensions to RSVP for LSP Tunnels"), confirms that an alternative, standardized mechanism for creating MPLS tunnels exists and is intended for use in MPLS networks.