Application Layer Http,ftp,tftp,telnet,dns,email

IP route Selection

CRC check

Packet forwarding sub-module

TTL value

IP output queue/input queue
ICMP message

routing table

IP is the network layer TCP is the transport layer

Application Layer
Presentation Layer
Session Layer
Transport Layer
Network layer
Link Layer
Physical Layer

NIC works on link layer

NIC is a network component which works on the link layer, is the interface of connecting computer and transmission medium in LAN, not only can realize physical connection and electrical signal matching between the transmission media of LAN, but also involves the sending and receiving of frames, the encapsulation and unpacking of frames, the media access control, the encoding and decoding of data and the function of data cache.

The NIC is equipped with a processor and memory (including RAM and ROM). The communication between the network card and the local area network is carried out in serial mode via cable or twisted pair wire. The communication between the network card and the computer is carried out in parallel by the I/O bus on the motherboard of the computer. Therefore, one of the important functions of the NIC is to perform serial/parallel conversion. Because the data rate on the network is not the same as the data rate on the computer bus, the memory chip that caches the data must be installed in the NIC.

The protocol stack (Protocol stack) refers to the sum of the protocols in the network, and its image reflects the process of file transfer in a network: from the upper layer protocol to the underlying protocol, and then from the underlying protocol to the upper layer protocol. The most widely used is the Internet protocol stack, the top-down protocols are: Application layer (Http,ftp,tftp,telnet,dns,email, etc.), Transport layer (TCP,UDP), Network layer (IP), link layer (Wi-Fi, Ethernet, Token Ring, FDDI, Mac, etc.), physical layer.

Application Layer Http,ftp,tftp,telnet,dns,email