Confusing network Fundamentals (01)

OSI (layer 7)

Application Layer : An application that can generate network traffic

Presentation Layer : Packet compression, encryption

Session Layer : Maintaining contact between the server and the client

Transport Layer : Reliable transmission (three-time handshake, flow control, packet loss retransmission) unreliable transmission

Network layer : Computer connection, establishment, termination, select the best network path

Data Link Layer : Mac data frame recognition, error checking

Physical layer : standard voltage standard for network device interfaces

Network troubleshooting

Physical layer (network cable)

Data link failure port rate inconsistent MAC address conflict

Network layer failure, IP, gateway, or subnet mask error

Application layer failure, application configuration

OS Error Reload restart format

Transport Layer Security Land attack (same as source address and destination address), you can set the policy on the router

Network equipment

Network cable (8, 4 pair) Gigabit Ethernet will only use 8

Nic MAC address (48-bit binary) cannot be changed

hub (hub) bandwidth sharing, there will be conflicts for optimization with bridge (learning function)

Switch : Ability to construct MAC address, bandwidth exclusive, forwarding broadcast packet to all interfaces

Routers : Different network segment forwarding data, can choose the best path, traffic management, isolation broadcast

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The encapsulation process of the data

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Confusing network Fundamentals (01)