VPLS is implemented in a Layer 2 network with 2000 VLANs. Which must be the primary concern to ensure successful deployment of VPLS?

The MPLS transport underlying VPLS is a mature and well-understood technology - while it must be correctly provisioned, it is not the primary concern specific to deploying VPLS across a large number of VLANs.

PE router capacity is a hardware design and capacity-planning concern that is addressed before deployment, not the primary operational concern that governs whether a VPLS deployment will function correctly at scale.

VPLS emulates a LAN service over MPLS by building a full mesh of pseudowires between PE routers, and MAC address learning depends on flooding unknown unicast, broadcast, and multicast frames to all PE peers in the mesh - there is no built-in control-plane mechanism for MAC advertisement. In a deployment with 2000 VLANs, this flooding replicates traffic across the entire MPLS core for every unknown MAC, creating significant bandwidth and PE CPU overhead. Addressing this flooding behavior - through mechanisms such as BGP MAC/IP advertisement or MAC learning optimizations - is the primary concern that must be managed for successful large-scale VPLS deployment.

The scenario already defines 2000 VLANs as the given deployment parameter, so VLAN scalability is a prerequisite constraint rather than the primary concern - the central issue is how VPLS behaves operationally within that environment.