A passive network is a type of computer network in which each node works on a predefined function or process. Passive networks don't execute any specialized code or instruction at any node and don't change their behavior dynamically. Typically, this behavior is related to each network router node.
Techopedia explains Passive Network
A passive network is one of the most common types of network found in most network environments. It requires that the entire network infrastructure be predesigned and configured prior to operation. When a packet passes through a network node in a passive network, that node only performs those actions configured within it. The router cannot execute or process any code passed within the packet data. The passive nature of the router is related to its routing tables or entries, which are only updated manually by the administrator or through neighboring routers.