Load balance four layer seven layer

As the core of the existing network with the increase of traffic volume, the traffic volume and the rapid growth of data flow, its processing capacity and computing strength correspondingly increased, so that a single server equipment can not afford. In this case, if you throw away an existing device to do a lot of hardware upgrades, this will result in the waste of existing resources and, if faced with the next increase in business volume, this will lead to a high cost of hardware upgrades again, and even the most performance-enhancing equipment will not meet the current business growth requirements.

Load balancing (also known as load sharing), the English name is the load Balance, which means to balance the load (work task) to multiple operational units for execution, such as Web servers, FTP servers, enterprise-critical application servers, and other mission-critical servers, In order to complete the work task together.

The so-called four layer is based on the ip+ Port load balancing, seven layer is based on the URL and other application layer information load balancing.

The four-tier load balancing is achieved by releasing the three-tier IP address (VIP), then add the four-tier port number to determine which traffic needs to be load-balanced, NAT process the traffic to be processed, forward to the backend server, and record which server the TCP or UDP traffic is handled by. All subsequent traffic for this connection is also forwarded to the same server for processing.

The seven-tier load balancing is based on the four layer (no four layers are absolutely impossible to have seven layers), consider the characteristics of the application layer, compared to a Web server load balancing, in addition to the VIP plus 80 ports to identify whether the traffic needs to be processed, but also according to the seven-level URL, browser category, Language to determine whether load balancing is to be performed. For example, if your Web server is divided into two groups, one for the Chinese language and one for the English language, then seven-tier load balancing can automatically identify the user's language when the user accesses your domain, and then select the corresponding language server group for the load balancing process.