Modules and interface cards are specifically designed for mid-to-high-end modular routers and switches. They are not applicable to routers and switches with fixed configurations. Generally, network modules are developed to expand the functions of local area networks, while interface cards usually refer to wide area network interface cards. Through wide area network interface cards, routers and switches can conveniently achieve more efficient wide area network access. Products with modular design have the advantage of effectively protecting user investments, truly allowing for on-demand purchasing, and enabling strong expansion capabilities to meet the constantly expanding needs of business.