Load balancing to multiple servers by way of the formation of a symmetric collection of servers, each server has the equivalent status, can provide services outside alone without the aid of other servers.Through some sort of load balancing technology, the external request sent to evenly assigned to the symmetrical structure of a server, the server receives the request and respond to client requests independently.Balancing the load equally distributed to client requests to a server array, whereby to provide fast access to important data, to solve a large number of concurrent access to service issues.The cluster with the least investment in technology can get close to the performance of the mainframe.
The advantages of network load balancing
First, the network load balancing incoming requests can spread to as many as 32 servers, which can use up to 32 servers to share external network request services.Network load balancing technology to ensure that even under heavy load, the server can respond quickly;
Second, just outside the network load balancing to provide a IP address (or domain name);
Third, when the network load balancing in one or a few servers is unavailable, the service is not interrupted.Network Load Balancing automatically detects the server is unavailable, the remaining servers can be quickly re-assigned to the client communications.This protection can help you to key business processes to provide uninterrupted service, and can increase the network traffic to a corresponding increase in the number of network load balancing servers;
Fourth, the network load balancing can be implemented on a computer in general.
Implementation process of the network load balancing
In Windows Server 2003, network load balancing of applications, including Internet Information Services (IIS), ISA Server 2000 firewall and proxy server, VPN virtual private network, Terminal Server, Windows Media Services (Windows video on demand, video broadcasting) and other services.At the same time, network load balancing helps improve server performance and scalability to meet growing client demand for Internet-based.
Network load balancing allows the client to use a logical Internet name and virtual IP address (also known as the cluster IP address) to access the cluster, while retaining their respective names for each computer.Below, we will install the Windows Server 2003 on two common computer, introduced the network to achieve load balancing and application.
This two computers, one computer name is A, IP address 192.168.0.7; another named B, IP address is 192.168.0.8.Planning the network load balancing virtual IP address dedicated 192.168.0.9.When the formal application, the client using the IP address of 192.168.0.9 only need to access servers, network services, according to a balanced load on each server automatically selected to provide services outside 192.168.0.7 or 192.168.0.8.Realization process is as follows:
Network load balancing in achieving each computer, can only install TCP / IP protocol, do not install any other protocols (such as NetBEUI or IPX protocol agreement), which can be from the "Network Connection Properties" in the view.
The first step, respectively, log on as Administrator A machine and the B machine, open the two machines of the "local connection" properties screen, check the "This connection uses the following items" in the "load balancing" item and go to "Properties" dialog box, the IP address are set to 192.168.0.9 (ie load balancing private IP), subnet mask to 255.255.255.0;
The second step, respectively, into A and B machine machine "Internet Protocol (TCP / IP)" property set interface, click the "Advanced" button, the pop-up "Advanced TCP / IP Settings" to add IP address of 192.168.0.9 interfaceand subnet mask of 255.255.255.0.
The third step, the two computers out of the "Local Area Connection Properties" window, patient for a while let the system complete the setup.
Then, if the two servers can not meet demand, these steps can add a third, fourth computer to the network load balancing system to meet the requirements.
IIS authentication with network load balancing service
After the network load balancing configuration, in order to achieve a specific service, load balancing in the network install the service on a computer.For example, IIS Web site in order to achieve load balancing, you need to network load balancing in the corresponding IIS services installed on the server.To allow each user to access the network load balancing to a different computer, you can gain access to consistent data, load balancing in the network on each computer to maintain data consistency.For example, the realization of a two-node network load balancing IIS, in order to ensure the consistency of the contents of the two sites, in addition to the two IIS server is configured the same, the corresponding site data must be consistent.
To test the network load balancing, we can IIS for authentication, other applications such as Terminal Services, Windows Media Services and IIS applications with it is similar.IE other browser on the computer, type 192.168.0.9, the network load, network load balancing will be automatically forwarded to the A or B machine machine.To verify the results, you can view the time, unplug the network cable the first computer or unplug the network cable the second machine, will find here will be different to the content.Of course, when we tested, in order to verify the effect of network load balancing, set the two sites over the contents, and when the formal application, network load balancing cluster, each node of the computer's content is the same, soRegardless of which node response, can guarantee access to the content is the same.
Load balancing the application of the Campus Network
Campus Network in addition to teaching, research, management, library information retrieval of information, but also take any of the internal and external information exchange, e-mail, bulletins, press releases, and various public networks access to the mouth of the tasks.Since the information transmitted over the network is not just numbers, text and graphics, but also with the application level, gradually increase the voice, moving images and high-bandwidth video applications.Therefore, the network construction, particularly for high-bandwidth backbone network with high speed campus network application server load balancing technology may well be a cheap solution.