A method for implementing load balancing, an apparatus, and a network system, where a controller obtains a port attribute of each port of a first switch in a mesh network, determines, according to the port attribute of each port of the first switch, a virtual routing and forwarding instance corresponding to each port of the first switch, where all user-side ports of the first switch correspond to a first virtual routing and forwarding instance, generates a forwarding table of the first switch according to a topology of the mesh network and the virtual routing and forwarding instance corresponding to each port of the first switch, where a first forwarding entry of the forwarding table includes the first virtual routing and forwarding instance, a destination network segment and at least two forwarding paths corresponding to the destination network segment, and sends the forwarding table to the first switch.