Network Basic 1 vswitch vro7 OSI7 layer model, network basic osi7

Network Basic 1 vswitch vro7 OSI7 layer model, network basic osi7
Chapter 2 network basics 1st network appearance

Solve computer communication requirements

Computer Information can be transferred

1.2 Basic Requirements for communication between hosts (three elements)

①. Physical connections must be established between two hosts. physical connections include network cables, optical fiber cables, and wifi and Bluetooth. These methods are collectively referred to as media;

②. The two hosts can identify data information and use the established protocol standards in binary mode.

③ Convert the binary number into an electrical signal so that the media can identify the transmission and use the NIC to send/receive data:

When sending data, convert the binary data to an electrical signal.

Restores an electrical signal to a binary number when receiving data.

Different signals are modulated or received through the NIC; 10 M 100 M 1000 M 100 Mbps = M bits can be transmitted per second

1.2.1 network cable and optical fiber

An electrical signal is transmitted using a network cable.

Optical signals are transmitted using optical fibers.

1.2.2 information transmission in Computer

The computer uses binary to represent data information:

Instance 1-1 for example:

Hello = 01 01 = Hi, use high voltage to identify binary signal 0 low voltage 1 High Voltage

Instance 1-2 multiple consecutive high/low voltage

000 111 ==>> only one signal is received and sent per second

There will be a corresponding network rate of 100 mbps = The number of packets transmitted per second on the NIC

100 M = 100000 K = 100000000bit 0 1 collectively referred to as bit stream)

1.2.3 three factors affect network transmission efficiency

The sender's Nic Rate

Nic speed of the receiver

Transmission rate of transmission media

1.2.4 Data byte and bit conversion formula

Network FIELD: identifying data information --- bit

System field: Identify data information-byte bytes

1 byte = 8bit 1bit = 1/8 byte

Chapter 2 Why do vswitches and vrouters need vswitches 2.1.1

To achieve mutual communication between multiple hosts

A vswitch can isolate conflicting domains, but cannot isolate broadcast domains.

2.1.2 requirements for mutual communication between vswitches

01) find the person who needs to accept my information and implement it through broadcast in an exchange network.

02) Let the recipient know that the received information is sent to him. The network ID, that is, the mac address, must be used.

The mac address is a physical address, which is globally unique.

03) when too many broadcast packets are sent in the network, the performance of hosts on the network is also affected,

This problem is called a broadcast storm.

The impact of a broadcast storm is only in one LAN.

In a LAN, all hosts are in a broadcast domain, and the number of ports in a vswitch is the number of conflicting domains.

2.1.3 vswitch features

All terminal devices connected to the port of a vswitch are in one CIDR Block (called a broadcast domain)

In addition, a CIDR block has a uniform network ID, which will generate broadcast consumption of device cpu resources.

A vswitch can isolate conflicting domains. Each port is a conflicting domain.

Terminal Device Access

Basic Security Functions

2.1.4 broadcast storm

Broadcast storm (broadcast storm) means that when broadcast data is flooded with the network and cannot be processed, it occupies a large amount of network bandwidth, leading to the failure of normal services or even complete paralysis, this caused a "broadcast storm ". A data frame or packet is transmitted to each node on the primary network segment (defined by the broadcast domain). Due to Network Topology Design and connection problems, or for other reasons, the broadcast can be replicated in a large number in the network segment, transmitting data frames, resulting in a decline in network performance, or even network paralysis. This is a broadcast storm.

2.2 why vro2.2.2.1

It is necessary to isolate broadcast storms so that hosts in different LAN can communicate with each other.

2.2.2 interconnection of multiple routers

When multiple routers are interconnected and route table information is unified and consistent, it is called "route table convergence". When routers whisper to each other, the router protocol is used to achieve route convergence.

2.2.3 host identity information

Lan code + host code = router ID information

Network Segment (Network Address) + host address = IP Address

2.3 routing protocol 2.3.1 static Router Protocol

You need to manually specify the target network that I want to arrive at. Which interface does the router use to connect

(Fast route table convergence)

2.3.2 dynamic Router Protocol

In broadcast-like mode, each vro informs other connected vrouters of the networks I connect.

(Easy configuration and operation-rip ospf)

2.4 broadcast domain and conflict domain

Router: each port is a broadcast domain and a conflict domain.

Vswitch: each port is a conflict domain, and one vswitch has a broadcast domain.

Chapter 2 network division 3rd network hierarchy

Core layer, aggregation layer, and access layer

3.1.1 core layer

The core layer mainly aims to provide oil painting and reliable Backbone Transmission Structure through high-speed forwarding communication. Therefore, the core layer switch should have higher reliability, performance, and throughput.

3.1.2 aggregation Layer

The component located between the access layer and the core layer is called the distribution layer or aggregation layer. The convergence layer switching layer is the aggregation point of multiple access layer switches. It must be able to process all traffic from the access layer devices, and provides the uplink link to the core layer. Therefore, compared with the access layer switch, the aggregation layer switch requires higher performance, fewer interfaces, and higher switching rate.

3.1.3 access layer

The access layer is usually called the access layer, which allows end users to connect to the network. Therefore, the access layer switch has the characteristics of low cost and high port density.

3.2 by scale

Lan, man, Wan

3.2.1 LAN

Local private network. If it is a large-scale LAN, it will also become a shared campus network.

3.2.2 man

If a network covers an urban area, it can become a man.

3.2.3 Wan

If the covered area reaches the whole country or the whole world, it will become a wan. The world's largest Wan is the internet.

Chapter 2 OSI7 Layer Model composition 4th Model Structure

From top to bottom.

Layer	Function	Data Unit
Application Layer	Network process to application. The Protocol, timing, and representation of specific application layers are encapsulated. Software is used in the end system, such as HTTP.	Data (Data)	Host Layer
Presentation Layer	Data Representation, encryption and decryption, convert machine-related data into machine-independent data. Specifies the format of the data, such as format conversion.
Session Layer	Communication between hosts to manage sessions between applications. Specifies the communication sequence; defines and synchronizes data exchanges, and creates checkpoints.
Transport Layer	Data packets are reliably distributed among nodes in the network. All legacy transmission problems; multiplexing; traffic; reliable o	Segments (Data Segment)
Network Layer	Address Allocation, routing, and (not necessarily reliable) packet distribution between nodes in the network. Routing (IP addressing); congestion control.	Datax Network Group/data packet	Media Layer
Data Link Layer	A reliable point-to-point data straight line. CRC code; multi-channel access; Addressing	Bit/Frame (data Frame)
Physical Layer	A (not necessarily reliable) point-to-point straight line data. Define mechanical properties; electrical properties; functional characteristics; Process Characteristics	Bit)

Thoughts: How to Use the OSI7 layer model to achieve interconnectivity between hosts