A customer requests a VPN solution to connect multiple sites with the company headquarters.

VPLS is the appropriate design model when multiple remote sites must appear to share the same Layer 2 segment. Because all sites use the same IP subnet, the solution must preserve a common broadcast domain rather than require Layer 3 route exchange between unique subnets. Cisco VPLS provides multipoint Layer 2 VPN service across a provider network, allowing customer edge devices at different sites to communicate as though they were attached to the same Ethernet LAN. Including 802.1Q connectivity on the LAN-facing side of the CE is the practical requirement because the CE must carry the relevant VLAN toward the provider-delivered VPLS service. Route exchange with the provider is not the main mechanism because VPLS is a Layer 2 service. NAT would hide overlapping addressing, but it would defeat the requirement to keep the same subnet operational across the sites. Placing each site in a different VLAN would also break the shared-subnet design. The correct design is therefore VPLS with VLAN tagging on the CE LAN side. Reference topics: VPLS, Layer 2 VPN, 802.1Q trunking, shared subnet extension, Ethernet WAN design.