Shulou(Shulou.com)06/02 Report--

Chapter 1 Cloud Computing Related Network Foundations

Computer Network Reference Model:

Construction: ① layered thinking

OSI Reference Model

③TCP/IP protocol family

④ Data encapsulation and decapsulation process

5 Interlayer communication process

OSI Seven-Layer Reference Model

1. International Organization for Standardization (ISO)

2.1984 The Open Systems Interconnection (OSI) Reference Model was promulgated in

3. An open architecture that divides the network into seven layers

stratified functional

Application Layer: An interface between network services and end users

Presentation layer: presentation, security, compression of data

Session layer: establishing, managing, and terminating sessions

Transport layer: defines protocol port numbers for transmitting data, as well as flow control and error checking (ports and services open)

Network layer: logical address addressing, path selection between different networks (need to consider the lowest cost path)

Data link layer: establishing logical connections, performing hardware address addressing (physical), error checking and other functions (reaching the destination physical node)

Physical layer: establishing, maintaining, and disconnecting physical connections

Physical layer:

1. How to use physical signals to represent data 1 and 0;2. Whether data transmission can be carried out in both directions simultaneously;3. How communication parties establish and terminate connections;4. Physical interface characteristics

Data Link Layer:

1. Data frame encapsulation structure (MAC);2. Physical addresses of source and destination;3. Data verification function

Network layer:

1. packet encapsulation structure (IP);2. logical addresses in source and destination directions;3. routing based on logical addresses in packet headers

Transport layer: (TCP/UDP protocol, directly associated ports)

1. Data segment encapsulation structure communication between user processes;2. link between the preceding and the following

Thinking: What is the difference between end-to-end and point-to-point communication?

Point-to-point: care about how to get there, how to locate, addressing, choosing the shortest route (route selection)

End-to-end: don't care about how to get there, how to locate, only care about the service opening

Session Layer:

1. Establish conversational relationships between users

Presentation layer:

1. Define syntax and semantics of information to be transmitted;2. Encoding and decoding, compression and decompression, encryption and decryption

Application layer:

1. Provide interface with users

TCP/IP protocol family:

1. Application layer: HTTP website (hypertext transfer protocol)

FTP (File Transfer Protocol) speed is not fast, capacity security, loading files

TFTP (Simple File Transfer Protocol) High efficiency, small capacity

SMTP (Mail Transfer Protocol, port 25)

SNMP (Port Scan Protocol for local area network)

DNS (domain name resolution to IP)

2. Transport layer: TCP (feature: security protocol) e.g. Thunder download tools, breakpoint restart

UDP (Features: Efficient Protocol) For example: QQ, WeChat and other communication tools will return the header to resend when the message is unsuccessful.

3. Network layer: ICMP (Data Message Control Protocol) ping tool

IGMP User Data Message Management Protocol

IP

ARP IP-->MAC

RARP (Reverse Address Resolution Protocol) MAC-->IP

4. Data Link Layer, Physical Layer: Protocols defined by the underlying network

Data encapsulation process: PDU

Application Layer Upper Data

Transport Layer TCP Header/Upper Layer Data (Data Segments)

Network layer IP header/TCP header/upper layer data (packets)

Data Link Layer MAC Header/ IP Header/TCP Header/Upper Layer Data (Data Frame)

physical layer bit stream

Corresponding relationship between equipment and layer:

application layer computer

Transport Layer Firewall

network layer router

data link layer switch

Physical layer network card, network cable, optical fiber

To sum up the above, I use a case in life to illustrate the relationship between the seven layers as a whole.

Application layer: Zhang San plans to order a takeaway for lunch.

Presentation layer: Compared with several major take-out platforms, finally chose Meituan take-out.

Conversational level: the chef of the business uses raw materials to make it for him and packs it for him.

Transmission layer: The merchant marked the order number on the takeaway and immediately called the takeaway brother. After negotiation, the takeaway brother decided to ride

The electric donkey delivers the takeaway to the customer Zhang San.

Network layer: The takeaway brother knows the customer's address, and measures the length of the three roads to the customer's home and the traffic situation, and decisively chooses the route with long route but smooth traffic.

Data link layer: after confirming that the takeaway address and customer address are correct, they are delivered within a specified time.

Physical layer: Zhang San received the takeaway delivered by the takeaway brother at his door.

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