Network and network protocol

Network and network protocol 1: Network 1. Basic concepts of communication two objects transmit information through a certain medium. 2. Signals and communication signals: convert data and signals into electronic signals, it is transmitted in the form of electromagnetic waves. Broadband: signals can be seen as the synthesis of electromagnetic waves of different frequencies. We can combine the signals of different products to obtain a new signal. The spectrum of this new signal, is the combination of the frequencies. The range of the spectrum is the bandwidth of the signal. Generally, most of the energy of the signal is concentrated in a small segment of the whole broadband, which becomes the effective bandwidth of the signal. 3. Common networks: LAN & WANLAN: local area network, that is, local area network. WAN: wide area network, that is, WAN. 4. Concept 2 of network system software: basic concepts of network protocols 1. Data communication and network model network protocols: to allow computers to communicate with each other, A set of languages that both parties know must be defined. Since not every node has a physical link, the communication protocol or rules can be divided into two parts: point-to-point: the waterproof end-to-end of the communication between two points with a physical connection: there is no direct physical connection, but the communication between two points is indirectly connected. 2. Internet 3, IP Address 4, Internet ARP: Address Resolution Protocol, is a well-known Address translation mechanism on the Internet. Its main function is to convert an IP Address to a physical Address, the physical address is followed by the NIC (or network interface). the physical location of the NIC sold by the vendor is allocated to avoid duplication, but the address is too long, the format is not uniform, so the Internet has its own address customization method.