What Is a Balanced Load?

Load balancing has different concepts in different fields. The basic concept is to alleviate the load of one or some entities, and assign tasks to multiple entities through a certain strategy to achieve load balancing among different entities.

Chinese name: Load balancing

Foreign name: Load balancing

NAT Load balancing NAT load balancing concept

Load balancing is also called NAT load balancing. Load balancing technology is commonly used in multi-WAN router access to achieve bandwidth aggregation.

NAT Load balancing NAT load balancing principle

Load balancing NAT (Network Address Translation) is simply to translate an IP address into another IP address, which is generally used to translate between unregistered internal addresses and legal, registered Internet IP addresses. It is suitable for situations where Internet IP addresses are tight and you do not want to let the outside of the network know the internal network structure.

This kind of load balancing is the basis of the current bandwidth convergence technology of multi-WAN routers. Take Xinxiang router as an example:

The multi-WAN router implements the industry's advanced dynamic load balancing mechanism. The multi-WAN port dynamic load balancing technology can dynamically distribute the data traffic of the internal network when using multiple lines, and dynamically implement the function of bandwidth aggregation. Load balancing mechanism:

a. Session: All enabled WAN ports work in an even session.

If the first connection session flows out through the WAN1 port, the next session automatically selects WAN2 to flow out, and the third session selects the WAN3 port to flow out (assuming all WAN ports are enabled)

This method is suitable for bundling multiple lines with the same bandwidth.

b. This method is suitable for multiple lines with different bandwidths to work better together. For example: WAN1 is connected to a 512K ADSL, and WAN2 is connected to 2M optical fiber. In this case, we can set the ratio to 1: 4 so that the bandwidth of the two lines can be fully utilized.

c. Traffic: Load is distributed according to data traffic. The system automatically selects the WAN port with the smallest traffic as the exit.

This method is applicable to the case where multiple lines are mixed when the line is unstable. When a certain line is temporarily unavailable or the line is unstable, traffic will be automatically distributed to another stable line. However, this method is not recommended when multiple lines are stable.

With these three types of load balancing, the router can flexibly cope with the complex situation of mixed use of multiple lines, support mixed connection of multiple lines, support multiple protocols, and can meet multiple complex applications.

Load balancing operation

On each computer that implements network load balancing, only the TCP / IP protocol can be installed. Do not install any other protocols (such as the IPX protocol or the NetBEUI protocol). This can be viewed in the "Network Connection Properties".

The first step is to log in to machine A and machine B as administrators, open the Local Connection property interface of both machines, check the "Load balancing" item in "This connection uses the following items" and enter the "Properties" dialog Box, set the IP addresses to 192.168.0.9 (that is, the dedicated IP for load balancing) and the subnet mask to 255.255.255.0;

The second step is to enter the "Internet Protocol (TCP / IP)" property setting interface of machine A and machine B respectively. After clicking "Advanced" button, add the IP address 192.168.0.9 in the "Advanced TCP / IP Settings" interface And the subnet mask is set to 255.255.255.0.

The third step is to exit the "Local Area Connection Properties" window of both computers and wait patiently for the system to complete the settings.

In the future, if the two servers cannot meet the requirements, you can add the third and fourth computers to the network load balancing system according to the above steps to meet the requirements.

Load balancing implementation

In Windows Server 2003, network load balancing applications include 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 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 the cluster IP address), while retaining the name of each computer. In the following, we will introduce the implementation and application of network load balancing on two ordinary computers with Windows Server 2003 installed.

Of the two computers, one is named A and its IP address is 192.168.0.7; the other is named B and its IP address is 192.168.0.8. Plan the network load balancing dedicated virtual IP address to 192.168.0.9. When it is officially applied, the client only needs to use the IP address 192.168.0.9 to access the server, and the network service balance will automatically choose 192.168.0.7 or 192.168.0.8 to provide external services according to the load of each server.

Load balancing applications

Load balancing is a server collection composed of multiple servers in a symmetrical manner. Each server has an equivalent status, and can provide services independently without the assistance of other servers. Through some kind of load sharing technology, the requests sent from the outside are evenly distributed to a certain server in the symmetrical structure, and the server receiving the request responds to the client's request independently. Load balancing can evenly distribute customer requests to the server array, thereby providing fast access to important data and solving a large number of concurrent access service issues. This clustering technology can achieve performance close to mainframe with minimal investment.

Load balancing advantages

First, network load balancing can propagate incoming requests to up to 32 servers, that is, it can use up to 32 servers to share external network request services. Network load balancing technology ensures that the server can respond quickly even under heavy load;

Second, network load balancing only needs to provide an IP address (or domain name) to the outside world;

Third, when one or more servers in network load balancing are unavailable, there is no service interruption. When Network Load Balancing automatically detects that the server is unavailable, it can quickly reassign client traffic among the remaining servers. This protection can help you provide uninterrupted services for critical business processes and increase the number of network load balancing servers accordingly based on the increase in network traffic;

Fourth, network load balancing can be implemented on ordinary computers.