According to various examples, in a site network, a layer-2 gateway device via which a terminal accesses a layer-2 network establishes a virtual link and an IS-IS relation with a layer-3 edge device, sends information of an learned MAC address to the layer-3 edge device, receives a packet sent by the layer-3 edge device via the virtual link, performs tunnel decapsulation on the packet, and searches a local MAC forwarding table based on a VLAN ID and a destination MAC address in the decapsulated packet to forward the packet in the site network according to a search result.