A service provider wants to offer a service that allows customers to span VLANs across multiple campuses. Which configuration will allow this service provider to achieve its desired result with a…

RFC 2547 defines MPLS Layer 3 VPNs which operate at the IP level and not Layer 2, making it unsuitable for transparently spanning customer VLANs across campuses.

Carrier Supporting Carrier (CsC) is an MPLS VPN architecture for carriers providing MPLS backbone services to other carriers, not a solution for customer Layer 2 VLAN extension.

VPWS with 802.1Q requires the PE to maintain a separate service instance per customer VLAN (up to 4094), which significantly impacts PE scalability compared to QinQ's ability to aggregate many customer VLANs under a single provider tag.

VPWS (Virtual Private Wire Service) provides point-to-point Layer 2 connectivity suitable for spanning VLANs across sites. QinQ (IEEE 802.1ad) stacks an outer provider VLAN tag over the customer VLAN tag, allowing multiple customer VLANs to be tunneled within a single service provider identifier. This reduces the number of service instances PE routers must maintain, minimizing scalability impact compared to per-VLAN 802.1Q configurations.