Shulou(Shulou.com)06/01 Report--

1.ISO/OS reference model: physical layer, data link layer, network layer, transport layer, session layer, presentation layer

two。 The typical questions concerned by the physical layer are how to send 1 and 0, the duration of one bit, whether the connection can be made in both directions at the same time, how to establish and terminate the connection, etc., devices: repeaters, hubs

3. The main functions of the data layer are reliable data transmission on the unreliable physical layer, encapsulating user data into frames (Frame), performing CRC validation (cyclic redundancy test), and preventing the data of the high-speed sender from flooding the low-speed side, such as network card, bridge, etc.

Collision domain: the range affected by sending a unicast the broadcast domain is the range affected by sending a broadcast

Switch: ① traditional switch (belongs to link layer, a broadcast domain, each interface is a collision domain), ② VLAN switch (belongs to link layer, can be managed, can be divided into multiple VLAN, each VLAN is a broadcast domain, each interface is a collision domain, and can be configured with IP address), ③ layer 3 switch (more routing functions than VLAN switch, can be understood as switch + router Belongs to the network layer of OSI model)

4. Network layer, routers and layer 3 switches all belong to network layer devices, and they are devices applied to different network segments. Each port of the router belongs to a separate broadcast domain and is also a separate collision domain

5. In the transport layer, the end-to-end communication between user processes (End-to-End) is realized in the transport layer. The related protocols in the transport layer are TCP and UDP. We will often see these two protocol names appear in Windows CMD's "netstat-ano" command.

6. Session layer, the main services provided by session layer are session control, synchronization, retransmission, etc.

7. The main services provided by the presentation layer are data coding, compression, encryption and decryption, etc.

8. Application layer, which contains a large number of commonly needed protocols: HTTP-TCP80, FTP-TCP21, SMTP-TCP26,POP3-TCP110,DNS-TCP/UDP53,TELNET-TCP23, etc.

The corresponding relationship between 9.TCP/IP reference model and ISO reference model is: network access layer, internetwork layer, transport layer, application layer.

Network access layer: the functions of this layer include the mapping of IP address and MAC address, encapsulating IP into frames, providing physical media connection, receiving IP Datagram from the internetwork layer, and sending this packet through the underlying physical layer interface.

Internet layer

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