MindMap Gallery 2. Network reference model
2. Network reference model, OSI seven-layer model, which are application layer, presentation layer, session layer, transport layer, network layer, data link layer and physical layer, let's look at them together.
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This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
Network reference model
type
OSI seven-layer model, tcp five-layer peer-to-peer model, tcp four-layer standard model
OSI
Application layer
effect
Provide an interface/service to the application
protocol
http, https, ftp, TFTP, telnet, dhcp, dns, snmp, smtp, rip, bgp
Data name
datadata
Representative equipment
program
Presentation layer
Define codec format, decompression, encryption and decryption
session layer
Establish, manage, and terminate sessions between communicating parties
transport layer
Establish, maintain, and cancel an end-to-end data transmission process, reliable transmission (complete) and flow control (speed)
tcp, udp
segment segment
firewall
Network layer
addressing, addressing, routing
ip, arp, ICMP, ospf
packet package
Routers, layer 3 switches
data link layer
Encapsulation, framing, error detection
vlan, ethernet, ppp, PPPoE, stp, ISIS
frame frame
Layer 2 switches, network cards
physical layer
transmit bitstream
bit bit
Hubs, repeaters, cables
how good
What is the reference model?
It is a series of standards for network communication.
Why layer?
Make it easier for us to learn
What is stratification?
= step by step
Put the elephant in the refrigerator - open the refrigerator door, push the elephant in, close the refrigerator door
Who proposed the OSI reference model?
ISO-International Organization for Standardization
When I was studying, why did I learn the OSI seven-layer model instead of tcp/ip?
Because osi has a more detailed network structure and better theoretical design, it allows us to understand the network in more detail.
OSI reference model workflow?
To explain by sending an email, first edit the email at the application layer and then send it to the presentation layer. The presentation layer can encrypt and compress the email and then pass it to the session layer. At this time, the session layer will start the email. This message is fed back to you and sent to the transport layer. The transport layer segments the message. Because the data cannot be transmitted at once, it needs to be segmented [so it is called message segments], and then sends the segmented data to the network layer. This When the network layer encapsulates the segments and adds headers to form data packets, it also selects a transmission path to transmit the data, and then passes the data packets to the data link layer. The data link layer adds headers and trailers and encapsulates them into frames. , and finally the frame is sent to the physical layer to form a bit stream
What is the difference between session layer and transport layer?
The session layer is equivalent to the leader telling the transport layer to establish a connection, and the transport layer rushes to establish the connection.