A network system, comprising at least one controller and a plurality of forwarding devices, wherein the plurality of forwarding devices forms a plurality of network topologies; the at least one controller is configured to: allocate, according to an attribute requirement of a virtual link on a basic link in a network topology, a link global label to the basic link in the network topology based on the attribute requirement; and send a link binding relationship between the link global label and <a network topology ID, a basic link identifier, and an attribute> to the plurality of forwarding devices, wherein a link global label allocated to each virtual link is different, wherein the link global label is a virtual link label for identifying a virtual link; and the plurality of forwarding devices is configured to receive the link binding relationship, and generate, according to the link binding relationship, a label forwarding entry comprising a mapping relationship between the link global label and virtual link forwarding information, wherein the virtual link forwarding information comprises the basic link and specified attribute processing that are corresponding to the link global label; wherein the forwarding device comprises: a second interface, a second processor, and a third processor, wherein: the second interface is configured to receive the link binding relationship between the link global label and <the network topology ID, the basic link identifier, and the attribute>; the second processor is configured to generate, according to the link binding relationship, the label forwarding entry comprising the mapping relationship between the link global label and the virtual link forwarding information, wherein the virtual link forwarding information comprises the basic link and the specified attribute processing that are corresponding to the link global label; and the third processor is configured to: when a first packet received by the forwarding device carries a first link global label, find, by searching according to the first link global label, a first label forwarding entry corresponding to the first link global label, to determine forwarding information of a first virtual link corresponding to the first link global label, perform first attribute processing corresponding to the first link global label, and forward the first packet from a basic link corresponding to the first link global label. the second interface is configured to receive the link binding relationship between the link global label and <the network topology ID, the basic link identifier, and the attribute>; the second processor is configured to generate, according to the link binding relationship, the label forwarding entry comprising the mapping relationship between the link global label and the virtual link forwarding information, wherein the virtual link forwarding information comprises the basic link and the specified attribute processing that are corresponding to the link global label; and the third processor is configured to: when a first packet received by the forwarding device carries a first link global label, find, by searching according to the first link global label, a first label forwarding entry corresponding to the first link global label, to determine forwarding information of a first virtual link corresponding to the first link global label, perform first attribute processing corresponding to the first link global label, and forward the first packet from a basic link corresponding to the first link global label.