"TI layman" Network knowledge Notes-OSI reference Model

Many training institutions and training courses take the "OSI reference Model" as the beginning of the course, which is a very important foundation for us to learn the Internet. The following is the structure diagram of osi

OSI: layer 7 Application layer (Application)

Layer 6 presentation layer (Presentation)

Layer 5 session layer (Session)

Layer 4 Transport layer (Transport)

Layer 3 Network layer (Nerwork): ip, arp, icmp and other protocols, routing equipment, data transmission between networks

Layer 2 data link layer (Data Link): Mac head, switching equipment, data frames transmitted within the network

Physical layer 1 (Physical): bitstream bit, repeater, hub (for signal relay, × × amplification to increase transmission distance)

OSI advantages: each layer is independent of each other, and the change of one layer will not affect other layers; promote standardization; make the network easy to implement and maintain; achieve interconnection, interoperability and interoperability.

TCP/IP models are divided into five categories A, B, C, D and E.

Three kinds of ABC are mainly applied.

AVR 10.0.0.0-10.255.255.255 (generally used in public network)

BRV 172.16.0.0-172.31.255.255

C 192.168.0.0-192.168.255.255 (BC is generally used in private network)