A method for packet routing in a network is disclosed. The network includes a network controller, a first switch connected to the network controller, a first server directly connected to the first switch, and a second server. The network controller obtains network connection information of the two servers. The network connection information indicates that the first server belongs to a first subnet and the second server belongs to a second subnet, the first subnet and the second subnet are two different subnets, and the two different subnets are configured on a same router. The network controller sends configuration information to the first switch. The configuration information configures the first switch to modify a packet header of a packet sent from the first server to the second server, and forward the modified packet to the second server.