Horizontal traffic replaces vertical traffic and becomes the main network data flow. With the maximization of data center utilization and utility, the traditional three-layer network structure can no longer meet the demand. Web2.0 companies adopt more open architecture, namely leaf spine topology, and increase more horizontal transmission (between IDC and IDC / cloud) than traditional vertical transmission (between users and IDC / cloud) And cloud, IDC and enterprise), which reduces transmission complexity and improves business flexibility. The leaf spine data center increases more horizontal connection requirements, reflecting the network architecture is more flat. As shown in the figure below, the horizontal traffic between the data center and the data center will become the main body of Internet traffic, replacing the traditional vertical traffic.