The main function of the router can be understood as realizing the forwarding of information. Therefore, we call this process the addressing process. Because the router is between different networks, it is not necessarily the final receiving address of the information. So in the router, there is usually a routing table. According to the final address of the information transmitted by the transmitting website, find the next forwarding address, which network should be. In fact, to put it simply, it is like a courier company to send mail. The mail does not arrive at the final destination instantly, but through the sorting of different sub-stations, constantly approaching the final address, so as to realize the delivery process of the mail. The router addressing process is similar. The final address is matched in the routing table, and the next forwarding address is determined by an algorithm. This address may be an intermediate address, or it may be the final arrival address. [4]
The function of a router is to transfer data between different subnets. The specific functions are as follows:
(1) Realize the interconnection of IP, TCP, UDP, ICMP and other networks.
(2) Process the data. Send and receive data packets, with functions such as packet filtering, multiplexing, encryption, compression and protection walls for data.
(3) According to the information of the routing table, the next transmission destination of the data packet is selected.
(4) To exchange topology information between the external gateway protocol and other autonomous domains.
(5) Realize network management and system support functions.
