Introduction to server Network Load Balancing

What is load balancing?

Load balancing is composed of multiple servers in a symmetrical way of a server set, each server has the equivalent status, can be provided to the external service alone without the assistance of other servers. Through some load-sharing technology, the externally sent requests are evenly distributed to one of the servers in the symmetric structure, and the server receiving the request responds independently to the customer's request. The balanced load can distribute customer requests to server arrays, which provides quick access to important data and solves a large number of concurrent access service problems. This clustering technology can gain access to the performance of a large host with minimal investment.

Advantages of Network Load Balancing

First, Network Load Balancing can propagate incoming requests to up to 32 servers, that is, a maximum of 32 servers can be used to share external network request services. The Network Load Balancing technology ensures that the server can make a quick response even under heavy load.

Second, the Network load balanced external only need to provide an IP address (or domain name);

Third, the service is not interrupted when one or several servers in the Network Load Balancing are unavailable. Network Load Balancing automatically detects that the server is unavailable and can quickly reassign client traffic to the remaining servers. This protection can help you to provide uninterrupted service for critical business processes and increase the number of Network Load Balancing servers according to the increase of network traffic;

Finally, Network Load Balancing can be realized on ordinary computers.

The realization process of Network Load Balancing

In Windows Server 2003, Network Load Balancing applications include Internet Information Services (IIS), ISA Server 2000 firewall and proxy servers, VPN virtual private networks, terminal servers, Windows Media Services (Windows video-on-demand, video broadcast), and so on. At the same time, Network Load Balancing can help improve server performance and scalability to meet the growing demand for internet-based clients.

Network Load Balancing allows clients to access the cluster with a logical Internet name and virtual IP address (also known as a cluster IP address) while retaining the respective names of each computer. Below, we will introduce the implementation and application of Network Load Balancing on two common computers with Windows Server 2003 installed.

In both computers, one computer name is A,IP address 192.168.0.7, and the other is named B,ip address 192.168.0.8. Planning Network Load Balancing dedicated virtual IP address is 192.168.0.9. When the formal application, the client only need to use IP address 192.168 0.9来 Access server, Network Service balance will be based on the load of each server automatically choose 192.168.0.7 or 192.168.0.8 external services. The specific implementation process is as follows:

On each computer that implements Network Load balancing, you can only install the TCP/IP protocol and do not install any other protocols (such as the IPX protocol or the NetBEUI Protocol), which is viewable from network connection properties.

The first step, as an administrator to log on to A and B machine, open the two machine "local Connection" property interface, check "This connection use the following items" in the load Balancing item and enter the Properties dialog box, Set the IP address to 192.168.0.9 (that is, the load-balanced dedicated IP), setting the subnet mask to 255.255.255.0;

In the second step, enter the "Internet Protocol (TCP/IP)" property setting interface of A and B, respectively, and after clicking the "Advanced" button, add the IP address 192.168.0.9 and subnet mask set to 255.255.255.0 in the "Advanced TCP/IP Settings" interface that pops up.

Step three, quit the local Connection Properties window on both computers, and wait for the system to complete the setup.

Later, if the two servers do not meet the requirements, you can add a third, fourth computer to the Network Load Balancing system to meet the requirements.

Verifying Network Load Balancing with the IIS service

After the network load balance is well configured, in order to realize a specific service, it is necessary to install the corresponding service on the Network Load Balancing computer. For example, to achieve load balancing on an IIS Web site, you need to install the IIS service on the appropriate Network Load Balancing server. In order for each user to gain access to consistent data while accessing different computers through Network Load Balancing, data consistency needs to be maintained on each computer where the network load is balanced. For example, the Network Load Balancing of IIS with two nodes, in order to ensure the consistency of two Web site content, in addition to the same configuration of the two IIS servers, the corresponding site data must be consistent.

To verify Network Load Balancing, we can authenticate with IIS, and other applications such as Terminal Services, Windows Media Services, and IIS are similar. In IE browser on other computers type 192.168.0.9, depending on the network load, Network load balance will be automatically forwarded to a machine or B machine. To verify the effect, you can unplug the first computer or unplug the network cable from the second machine while browsing, and you will find different content. Of course, when we were testing, in order to verify the effect of Network Load Balancing, the two sites are set to inconsistent content, and in the formal application, Network load balanced cluster of each node of the computer content will be consistent, so no matter which node to use the response, can guarantee access to the content is consistent.

Application of load balance in campus network

The application of campus network, in addition to teaching, scientific research, management, library and information retrieval, but also undertake the school's internal and external information exchange, e-mail, announcements, press releases, as well as a variety of public network access and other tasks. As the information transmitted on the network is not only the number, text and graphics, but also with the application level, and gradually increase the voice, moving images and video images and other high bandwidth applications. Therefore, the network construction, especially the backbone network requires high bandwidth and high speed, in the campus network server application of load balancing technology is a cheap solution.