The main job of a router is to find an optimal transmission path for each data frame passing through the router, and to efficiently transmit the data to the destination site. It can be seen that the strategy of selecting the best path, that is, the routing algorithm, is the key to the router. In order to complete this work, the relevant data of various transmission paths - Routing Table (Routing Table) is saved in the router for use in routing. The path table stores the information of the subnet flag, the number of routers on the network, and the name of the next router. The path table can be fixed by the system administrator, or dynamically modified by the system, automatically adjusted by the router, or controlled by the host.

1. static path table

2. dynamic path table