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Table of contents
Foreword:
Dynamic Host Configuration Protocol is a network protocol for local area networks . It refers to a range of IP addresses controlled by the server . When the client logs in to the server, it can automatically obtain the IP address and subnet mask assigned by the server . The computer acting as the DHCP server needs to install the TCP/IP protocol , and set a static IP address , subnet mask, default gateway , etc. for it.
1. Information Introduction
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Chinese name: Dynamic Host Configuration Protocol server Foreign name: Dynamic Host Configuration Protocol
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Protocol standard: IETF RFC 2131, 3315 Abbreviation: DHCP Server
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Attribute: Network protocol Operating environment: Windows 2000 Server/Advanced Server system
1. What is DHCP service
dhcp stands for Dynamic Host Configuration Protocol. The DHCP method is used to assign temporary addresses to Internet users when the computer is connected to the Internet, and the DHCP server temporarily assigns an IP address from the address pool. The IP address assigned each time the Internet access may be different, which is related to the IP address resources at that time.
2.DHCP definition:
The full name of DHCP is Dynamic Host Configuration Protocol, which means "Dynamic Host Configuration Protocol" in Chinese. It is usually used in large-scale local area network environments. Its main function is to centralize management and assign IP addresses, so that hosts in the network environment can dynamically obtain IP addresses. Gateway address, DNS server address and other information, and can improve the utilization rate of addresses.
2. Scope
It is one of the TCP/IP protocol clusters and is mainly used to assign dynamic IP addresses to LAN clients. Disadvantages: DHCP has more broadcast overhead, which will cause a decrease in network operation efficiency and configuration difficulties for a metropolitan area network with a large number of users ; on the other hand, it still cannot solve the problem of users configuring their own IP addresses.
The dynamic allocation of public ip addresses is mainly through PPPoE .
3. Working principle
1. Distribution method
In the working principle of DHCP, the DHCP server provides three IP allocation methods: automatic allocation (Automatic allocation), manual allocation and dynamic allocation (Dynamic Allocation).
- Automatic allocation means that when the DHCP client successfully obtains an IP address from the DHCP server for the first time, it will use this IP address permanently.
- Manual assignment is an IP address specifically assigned by the DHCP server administrator
- Dynamic allocation means that after the client obtains the IP address from the DHCP server for the first time , it does not use the address permanently. After each use, the DHCP client needs to release the IP for other clients to use.
2. Lease process
The workflow of lease renewal is described as follows:
- When 50% of the lease period has passed, the client sends a unicast DHCP REQUEST message to the server to renew the lease period.
- If the DHCP ACK message from the server is received, the lease period will be extended accordingly, and the lease renewal will be successful. If no DHCP ACK message is received, the client continues to use this IP address. When 87.5% of the lease period has passed, send a broadcast DHCP REQUEST message to the server to renew the lease period.
- If the DHCP ACK message from the server is received, the lease period will be extended accordingly, and the lease renewal will be successful. If no DHCP ACK message is received, the client continues to use this IP address. When the lease expires, the client automatically gives up using this IP address and starts a new DHCP process.
4. DHCP service configuration
- For the erection of the DHCP server , the network card can be bridged when installing the virtual machine .
- DHCP is based on the client/server model. When the DHCP client starts, it will automatically communicate with the DHCP server, and the DHCP server will provide the DHCP client with the service of automatically assigning an IP address.
- Of course, advanced DHCP is not only as simple as assigning addresses. Our course today is just setting up an ordinary DHCP server, and the client can obtain the necessary network configuration information for Internet access.
- The server with the DHCP service software installed is called the DHCP server, and the client with the DHCP function enabled is called the DHCP client. The DHCP server provides services for the DHCP client in the form of an address lease. There are two ways.
5.DHCP service installation
The method of installing the DHCP service component in the Windows Server 2003 system is as follows:
Step 1, double-click the " Add or Remove Programs " icon in the "Control Panel" window to open the "Add or Remove Programs" window. Click the "Add/Remove Windows Components" button.
Step 2, open the "Windows Components Wizard" dialog box, double-click the " Network Service " option in the "Components" list .
Step 3, open the "Network Services" dialog box, select the " Dynamic Host Configuration Protocol (DHCP)" check box in the "Subcomponents of Network Services" list . Click the "OK"→"Next" button in turn.
Step 4, the system starts to install and configure the DHCP service component, click the "Finish" button after the installation is complete.
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