Computer Network Technology and Application

Chapter 26 Network Technology Application Examples (1)
The rapid development of Internet technology application has changed people's traditional way of life and work. Computer network has been widely used in different fields such as scientific research, education, national defense, and commerce, and has become an important infrastructure for information exchange and sharing. It not only enables people to timely and quickly It also provides a platform for various free exchanges and becomes a powerful driving force for social development.The understanding and use of network technology and even the establishment of a network with its own characteristics have become a skill that every computer network enthusiast should master.In this chapter, several commonly used network technology application examples will be introduced for your study and reference.

【Main content of this chapter】

demand analysis.

Equipment selection.

Choice of software.

Cyber ​​security scheme.

8.1 Design of office LAN establishment
At present, most enterprises and institutions have paid or started to pay attention to the construction of office automation and informatization. By connecting the computers in the office or between departments into a local area network, the business is paperless and networked, which improves work efficiency and reduces office costs.The office LAN can also be connected to the Internet, so that computers in the LAN can share the Internet and obtain Internet information resources.Based on a case, this section will elaborate on core issues such as how to set up and manage an office LAN, as well as common network services and network security measures in an office LAN.The main content includes the following 8 aspects:
Demand analysis, network overall design, network topology design, network hardware equipment selection, network server selection, Internet access, network services and network security measures.

8.1.1 Requirements Analysis

When we want to build a network, the first thing we should do is research and analyze user needs, clarify the functions and goals required by users, and help users achieve their goals based on the resources available.

[Case] ​​A research institute needs to set up a local area network. The research institute currently has 2 offices and 6 laboratories, and each room has a different number of computers with different configurations.Now it is necessary to network these computers to realize the sharing of information and resources within the unit, and to be able to access the ADSL telecommunications network and the education network (the institute has a fixed IP and ADSL account for the education network), so as to facilitate the query of literature and materials and improve work efficiency ; A Web server in the research institute needs to provide access to the outside world and provide FTP services; a printer needs to be shared within the research institute.At present, each computer is only used for some simple applications such as Office and professional software. Now it is necessary to develop an office automation system based on this, which is convenient for information query and sharing of all personnel in the unit, and realizes remote office by using the Internet.

8.1.2 Overall network design
The overall design should be carried out before the establishment of the local area network. The overall design is the general idea and engineering blueprint of the construction of the local area network, and is the core task of doing a good job in the construction of the local area network.The overall design mainly has the following steps.

(1) Carry out object research and demand investigation to clarify the needs and conditions of system construction.

(2) On the basis of demand analysis, determine the types of internal network services, and determine the specific goals of system construction, including network facilities, site settings, development and application, and management.

(3) Determine the network topology and functions of the LAN to be built, and conduct system analysis and design according to application requirements and office distribution characteristics.

(4) Determine technical design principles, such as standards and requirements in technology selection, wiring design, equipment selection, software configuration, etc.

(5) Plan and arrange the implementation steps of network construction.According to the requirements of the overall design above, in this case, we need to determine the most cost-effective network connection type according to the actual distribution of computers, and make reasonable wiring to realize the networking of all computers; and reserve certain ports to facilitate future network expansion; The local area network should be connected to the education network and the telecommunications ADSL network at the same time to ensure that all computer network switching and resource sharing are fast and convenient.To this end, carry out the following work.

① Establish a network server based on Windows NT Server to realize file and print sharing.

②Establish a Web server and develop an office automation system. Internal personnel can use the network to communicate and collaborate with each other, and provide external access to facilitate external personnel to understand information and query data in a timely manner.

③Establish a mail server to facilitate the communication, exchange and cooperation of internal personnel.

8.1.3 Network topology design
LAN network topologies mainly include bus, star, ring and hybrid, among which star topology is a more common and frequently used network topology.The star topology is composed of a central node and sub-nodes connected to the central node through point-to-point links. The central node executes a centralized communication control strategy to reduce the processing burden among sub-nodes.Compared with several other structures, the star network has the following advantages.

(1) The central node and network switching equipment are centralized to facilitate service provision and network reconfiguration.

(2) Nodes in the network are prone to faults. In the star topology, it is easy to clear faults, detect and isolate faults, and can easily delete fault points from the system without causing the entire network to collapse.

(3) Any connection in the star network only involves the central node and sub-nodes, so the method of controlling medium access is relatively simple.

According to the actual situation of the institute's computer distribution and combining the advantages of the star structure, the network design adopts the star structure.

8.1.4 Selection of network hardware equipment
When purchasing and using network equipment, the following factors should be considered.

(1) Due to problems such as difficult upgrades and limited effective transmission distances for network wiring, twisted-pair cables with better quality should be selected, such as unshielded twisted-pair cables such as Category [-]e and Category [-].

(2) It is not necessary to choose the latest and best network hardware equipment, but to choose equipment using mature technology, mainly in terms of cost performance and reliability.

(3) The equipment should be upgradeable, laying the foundation for future network upgrades.

8.1.5 Selection of web server
In various local area networks, the client/server mode access control method is centralized control, and the control core is a network server, which is generally a high-end microcomputer or a dedicated server with a large-capacity hard disk.

There are many types of server products in the market, with different grades, different performances, and different application fields.In actual network applications, how to choose a server that suits your needs is very important.When choosing a web server, you can consider the following aspects.

1. Selectivity and Transplantation

(1) Openness of the hardware system

The openness of the hardware system refers to the entire server, not a certain hardware technology in the service.If you decide to buy a traditional dedicated minicomputer structure, such as HP9000 PA-RISC, IBM PowerPC, SUN Ultra-Sparc, etc., try to buy only one company's products, because if you choose another company's server, you will have to overcome a lot Difficulties in upgrading and porting.

(2) Openness of hardware peripherals

Server hardware peripherals should feature selectivity and portability.In this way, you don't have to be limited to the products of a certain manufacturer, and you can choose the best ones to buy.

(3) Openness of internal hardware expansion

The internal hardware expansion of the server should have the characteristics of selectivity and portability.This mainly refers to CPU and memory.

The CPU of the server should have multiple compatible manufacturers.Such as Intel, AMD chips.

2. Performance and performance-price ratio

When comparing the performance between servers, in addition to considering some indicators, such as CPU speed, number of CPUs, whether the CPU bus structure is 32-bit or 64-bit, whether it is a CISC or RISC processor, cache cache size, system bus speed, I/O In addition to throughput bandwidth, network card speed, hard disk speed, etc., the following overall indicators should also be paid attention to.

(1) Scalability

Scalability refers to adding internal or external hardware.For example, expand the number of CPUs (SMP), increase memory, increase the number and capacity of hard disks, and increase adapters (cards) on the I/O bus, etc.

(2) Upgradability

An upgrade is the replacement of an existing, less performing component with a new hardware component.Such as the upgrade of the CPU processor.In some servers, the CPU is closely combined with the motherboard, so when upgrading the CPU, only the entire CPU board can be replaced, which is expensive.

(3) Reliability and availability

Server reliability can usually be measured by Mean Time Between Failure (MTBF).Although there is no unified standard for the calculation of MTBF, users can judge the reliability of the product by checking the reliability technology adopted by the server, such as redundant backup power supply, redundant backup network card, ECC (error check and correction) memory, ECC protection system Bus, RAID disk array technology, automatic server recovery, etc.Availability generally refers to whether there is a dual-machine backup function.Backup can be divided into cold backup, hot backup, dual-machine online at the same time, etc. Users can choose the backup method according to the criticality of the application.

(4) Compatibility

Generally speaking, as long as the hardware standard and software standard are met and an appropriate driver is provided, the compatibility problem can be solved.However, in a few cases, there will be micro-compatibility problems, such as conflicts between the hardware option BIOS and the system BIOS, and the inconsistency between the application software operation and the system BIOS. More often, the hardware BIOS and drivers need to be updated frequently.

(5) Manageability

In a large-scale distributed enterprise, there will be dozens to dozens or even hundreds of servers, and these servers may be physically distributed in different locations, which is a very difficult problem for system administrators at this time.Therefore, large-scale users should require server companies to provide server management technology, and must comply with SNMP (Simple Network Management Protocol) network management standards.

3. Select the network operating system
Network Operating System (NOS) is the interface between network users and computer networks, and is used to manage and control network resources.In addition to the functions of the general operating system, the network operating system should also be able to support a variety of communication protocols, provide reliable network communication and a variety of network service functions.The more popular network operating systems mainly include Windows Server 2003/2008, UNIX, Linux Server and so on.

WindowsServer 2003 inherits the friendly operability of WindowsXP and the powerful network support performance of previous Server systems, inherits the advanced technology of WindowsServer 2000 and makes it easier to deploy, manage and use, in terms of security, reliability, availability, manageability and scalability Performance and other aspects have been greatly improved, especially its enhanced support for network services, which can provide complete solutions for small and medium-sized enterprises.

Based on the advantages of WindowsServer 2003 mentioned above, here, we choose WindowsServer 2003 as the network operating system of the server, and many subsequent configuration operations are completed on WindowsServer 2003.

8.1.6 Internet access
After deploying the network according to the network topology diagram, the router, server and client computer network parameters need to be configured next, so that all computers in the LAN can communicate with each other and access the Internet.

1. Configure the router

Since the LAN needs to be connected to the education network and the telecom ADSL network at the same time, a router needs to be configured.At present, there are many ISPs (Information Service Providers) that provide ADSL services in the market. For example, Gehua Cable, Great Wall Broadband, and Beijing Unicom account for a large market share in Beijing. You can apply for ADSL services from corresponding ISPs according to actual needs. .In this example, use the ADSL service provided by China Unicom. ADSL adopts a dial-up access method, which can be realized by using the EnterNet300 virtual dial-up software; you can also use the built-in functions of the Windows Server 2003 operating system to establish a virtual dial-up connection. The specific operation steps are as follows.

(1) Select the "Start" → "Programs" → "Accessories" → "Communication" → "New Connection Wizard" command to open the "New Connection Wizard" dialog box, click the "Next" button.

(2) In the pop-up "Network Connection Type" dialog box, select the "Connect to the Internet" option, and click the "Next" button.

(3) In the pop-up "Internet Connection" dialog box, select the "Connect with a broadband connection that requires a user name and password" option, and then click the "Next" button.

(4) In the pop-up "Connection Name" dialog box, enter the ISP name as "Broadband Connection", then click the "Next" button, and in the pop-up "Internet Account Information" dialog box, enter the user name provided by the ISP and password, and click the "Next" button.

(5) To complete the new connection wizard, click the "Finish" button.After setting up the ADSL virtual dial-up connection, double-click the "Broadband Connection" icon on the desktop to open the "Connect Broadband Connection" dialog box; click the "Connection" button to access the Internet.

The IP parameter of the LAN port of the ADSL router is set to "192.168.1.1", and the subnet mask is set to "255.255.0.0".

The education network selects "static IP" for the EDU Internet access method, and sets the basic network parameters of the WAN port of the router according to the education network IP information (apply for the education network), and the IP in the basic network parameters of the LAN is set to "192.168.2.1. The mask is set to "255.255.0.0".

2. Server configuration

The server needs to provide web services to the outside world.You can use the static IP of the education network, and then use the port of the routing EDU to map to the port 80 of the server.Set the server IP to "192.168.1.101", the subnet mask to "255.255.0.0", and the gateway to "192.168.2.1". The specific configuration parameters are shown in Figure 8.8.

3. Configure the client

Each client computer is assigned an IP, the IP range is "1" ~ "192.168.1.2", the subnet mask is uniformly set to "192.168.1.100", and the gateway and DNS are selected according to the way of accessing the Internet.If the telecom network is selected, the gateway and DNS are set to "255.255.0.0".

If you choose the education network, set the gateway and DNS to "192.168.2.1".

8.1.7 Network Services
The server can provide many network services, such as Web service, file transfer service, email service, directory service, DNS service, database service, DHCP service, printing service, etc.

The following mainly introduces several commonly used network services: Web service, file transfer service, and email service. For other network services, you can refer to relevant reference materials for learning.

(End of this chapter)