LLD (Lom Level Desigm, detailed design) is based on the determined target network architecture, clearly designing the scope of the network and functional deployment plan; the specific design content was paid attention by the customers within the scope of the contract, including clarifying the interactive process of the important business, the function allocation of all services on each network element, the peripheral docking relationship of the design network element, the docking requirements and compliance with the norms, the quantitative calculation of docking resources.