Computer network Overview

1. What is a computer network?

A: The exact definition of a computer network is not uniform. The simplest definition is: a collection of interconnected, autonomous computers.

2. Classification of computer networks:

According to the scope of the network to classify:

1. Wan Wan (Wide area Network): range Dozens of to thousands of km

2. Metro Man (Metroplitan area Network): The range is generally a city, 5~50km

3. Lan LAN (local area Network): A range of about 1km, local in a small area, such as a school or factory

4. Personal Regional Network (Personal area Network): Range 10m

According to the users of the network classification:

1. Public network

2. Private network

3. How to evaluate the performance of computer network?

The performance index of computer network:

1. Rate: The rate at which a host transmits data over a digital channel on a computer network. Units for kb/s, MB/s,, etc.

2. Bandwidth: The highest data rate that can pass through a network from one point to another in a unit of time. Unit Ibid.

3. Throughput: The amount of data across the network per unit of time. Unit Ibid.

4. Latency: Data from one point to another in the time spent on the network, including: Transmission delay (information from the head to the end of the beginning of the time spent), propagation delay (information in the channel time spent), processing delay (the host or route to information processing time spent), Queue delay (packet propagation passes through many routers, which are queued for processing after entering the router).

5. Delay Bandwidth Product: = propagation delay * bandwidth.

6. Round trip Time round-trip: sends data from the sender to the receiving acknowledgement of the received information sent by the receiving party.

7. Utilization: Includes channel utilization (percentage of time a channel is used) and network utilization (weighted average of channel utilization across the network)

Non-performance indicators for computer networks:

1. Cost 2. Quality 3. Standardization (network hardware and software design is required in accordance with international standards) 4. Reliability 5. Scalable and upgradeable 6. Easy to manage and maintain

4. Architecture of the computer network

Network Protocol (Internet Protocol): The rules, standards, or conventions established by computer networks in order to exchange data methodically.

Architecture (architecture): The various layers of computer networks and their network protocols.

Architecture with five tiers of protocol:

1. Application layer (Application layer): Apply inter-process communication and interaction rules. (The process here refers to the program that is running on the host)

2. Transport layer (Transport Layer): Responsible for the communication between processes in two hosts to provide a common data transfer service. (Application process uses this service to transfer the application beginning)

The transport layer mainly uses two types of protocols:

TCP (Transmission Control Protocol) and User Packet Protocol (users Datag Protocol)

3. Network layer: Responsible for providing services to different hosts on the packet switching web. (The network layer encapsulates the message segments and user datagrams transmitted by the Transport layer as packets (also called IP packets) or packages for delivery)

4. Data link layer (datalink layer): The network layer is responsible for the intersection of IP packets assembled into a frame (framing), the link between the two adjacent nodes to transfer frames.

5. The physical layer (physical layer): Converts the frames passed down the data link layer into a bitstream for transmission.

summed up in Shehiren teacher's "computer network"

Computer network Overview