Which type of connectivity is required for VPLS?

VPLS emulates an Ethernet LAN across an MPLS or IP network by requiring that every PE router participating in the VPLS instance has a pseudowire (PW) connection to every other PE router. This full-mesh of pseudowires ensures that frames can be forwarded between any two customer sites as if they were on the same switched LAN segment, supporting broadcast and unknown unicast flooding to all members.

A partial mesh would leave some PE routers without direct pseudowires to others, breaking the LAN emulation model that VPLS requires for correct flooding behavior.

A star topology would centralize forwarding through a hub PE, which is not how VPLS operates and would not provide the any-to-any LAN emulation VPLS is designed for.

A bus topology is not a supported or practical VPLS design and does not satisfy the any-to-any forwarding requirements.

A ring topology does not provide the direct PE-to-PE pseudowires that VPLS requires for proper LAN emulation and would introduce unnecessary latency through intermediate hops.