IP address refers to the Internet Protocol address, also called Internet Protocol address, which is a unified address format provided by the IP protocol. It allocates a logical address to each network and each host on the Internet to distinguish physical addresses in reality, ensure that data packets can be accurately transmitted from the source address to the destination address, and realize point-to-point communication between network devices.
1. Format and structure of IP address
An IP address is a 32-bit binary number that is usually divided into 4 8-bit binary numbers (i.e. 4 bytes) and expressed in dotted decimal form, such as 114.234.70.116. Each IP address consists of a network number and a host number. The network number is used to identify the network, and the host number is used to identify the specific device in the network.
2. Classification of IP addresses
IP addresses are divided into five categories: A, B, C, D, and E.
Class A addresses are used on large networks
Class B addresses are used for mid-sized networks
Class C addresses are used for small networks
Class D addresses are used for multicast
Class E addresses are reserved for future use
3. How IP addresses work
IP addresses cannot be seen or touched in reality, so how does it work? How does it work? Taking the following example, when a user enters a URL in a browser, the packet is passed down from the application layer (such as HTTP) to the IP layer. The IP layer encapsulates the packet into IP datagrams and adds the source IP address and destination IP address. The datagram is forwarded through the router and finally reaches the destination network. In the destination network, the datagram is delivered to the destination host, completing the communication process.
The IP layer is located at the network layer and is responsible for transmitting data from the source address to the destination address. Data may be segmented into multiple packets during transmission (called fragmentation) and reassembled at the destination. The IP layer is also responsible for routing and determining the best path for packets to travel through the network.
Let's take travel as an example. If I want to travel somewhere, I need to first determine the travel method, such as taking high-speed rail, subway, bus, etc., and purchase the corresponding ticket, and then formulate a detailed itinerary based on the ticket information to record the travel time. The data link is equivalent to our ticket and can only move within the specified interval. The source address is the starting point, the destination address is the destination, and the network layer is equivalent to the entire itinerary.
If you only have a itinerary and no ticket, you cannot take transportation to your destination. On the contrary, if you only have a ticket and no itinerary, you will not know the vehicle information, transfer information, etc., and you will not be able to reach your destination either. Only by having both tickets for a certain section and a schedule for the entire trip can we ensure reaching our destination. The same is true in the network. The data link layer and the network layer need to work together to realize the transmission of the final IP address information. This is how IP addresses work.
