LLD (Lom Level Design) is based on the determined target network architecture, clearly designing the scope of the network and the functional deployment plan, the specific design content includes clarifying the interactive process and all services of the important business that the customer pays attention to within the scope of the contract, the function allocation of each network element, the design of the peripheral docking relationship of the network element, the docking requirements and compliance with the norms, the quantitative calculation of docking resources.