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Many beginners are not very clear about the solution of Radware global load balancer. In order to help you solve this problem, the following editor will explain it in detail. People with this need can come and learn. I hope you can get something.

one。 Demand analysis

No matter how perfect the redundancy mechanism, security tools and advanced load balancing technology are adopted in the user's data center, the operation mode of a single data center still can not guarantee the uninterrupted operation of key business. In order to satisfy that users in different locations around the world can have the same fast access experience when accessing applications, a single data center is implemented. Based on the above two main reasons, it has become an inevitable choice for users to build multiple data centers in different physical locations.

However, after building multiple data centers, how to coordinate among multiple data centers through effective means to guide users to visit the best site, or when a site has a catastrophic failure so that users can still access key business on other sites and other issues become the most concerned issues.

two。 Radware Global load balancing solution

Radware's global load balancing solution can help customers achieve higher availability, performance, and more economical and impeccable security by deploying the same service content in multiple data centers in different physical locations, so that customers around the world can get faster response time.

Radware's global load balancing solution supports all the functions of Radware's next-generation APSoluteOS software architecture, which completely solves the problems of network availability, performance and security, and makes applications more sensitive and adaptive in multiple data centers. The special hardware application switching equipment combined with Radware's high-speed and high-capacity ASIC chip + NP processor can effectively ensure the high availability of network applications, improve network performance, enhance security, and comprehensively enhance the appreciation potential of network infrastructure such as IT servers.

Based on Radware's years of experience in intelligent application traffic management and the analysis of users' actual needs, we believe that load balancers should have the following functions:

It can be used as a logical entry point for all data centers that provide the same service through a unique IP address or domain name.

Global load balancing switches have flexible traffic allocation algorithms and mechanisms to ensure that users can always access the content of the data center that can provide the best service for them.

Through the deployment of high-performance load balancing products, the health status of servers in each data center or within the data center can be found in time, and when a data center fails, ensure that the access of subsequent users is directed to the normal operation of the data center.

For session-based services, a variety of session persistence mechanisms can be provided to ensure the continuity of users when dealing with the business. Avoid the failure of access caused by assigning business requests for the same session of the user to different data centers.

It should have the functions of excessive security concerns and anti-DOS/DDOS to provide one more layer of security for the server.

It has good upgrade and scalability, and can adapt to specific and changing business needs.

2.1 Plan Topology Diagram

2.2 AppDirector-Global to achieve global and local load balancing

In terms of global and local load balancing, AppDirector-Global mainly implements the following functions in the network:

2.2.1 Global load balancing strategy

Radware

Support a variety of global load balancing strategies, through a unique IP address or domain name as the logical entry point for all data centers that provide the same service. According to the actual situation of the user, you can choose one of the following, or you can combine it at the same time.

Method one is based on DNS redirection

Support for proximity resolution based on LocalDNS location. When the user accesses through the domain name, the proximity calculation can be made according to the LocalDNS location used by the user, and the IP address of the best site can be resolved to the user.

The second method is based on network proximity judgment and wide area triangular redirection.

Compared with method 1, the difference of this global load balancing strategy is also the biggest advantage: AppDirector-Global can not only resolve the corresponding domain name, but also calculate and judge the optimal site according to the user's real IP address, and finally redirect user traffic to the corresponding service node. When the protocol used by the service requested by the user does not have a redirect command similar to "HTTP302", the smooth implementation of this strategy makes use of the unique "wide area triangle redirection" capability of RadwareAppDirector-Global products to complete the service redirection.

Mode 3 is based on http redirection

When the service requested by the user uses the http protocol, the AppDirector-Global can send the redirect command "HTTP302" to guide the user to the best site by calculating the nearest location of the user's real IP address.

Mode 4 is based on rtsp redirection

When the service requested by the user uses the rtsp protocol, the AppDirector-Global can send a "HTTP302" redirect command to direct the user to the best site through the nearest calculation.

2.2.2 proximity calculation

In order to accurately calculate that global users can direct users to the "optimal" data center when accessing resources, the global load balancer must go through careful calculation. Only after considering all the factors such as the distance between users to each site, the delay, and the load of the current data center, can we really judge the current "optimal" service data center.

Radware

The equipment supports two methods of proximity calculation, and it is recommended to use the two methods side by side.

Mode one static proximity operation

In this way, the static address table is used to guide the user's request. When the user's IP address or LDNS's IP address hits the static address table, AppDirector-Global directs the user directly to the best site that has been defined. When the static address table is not hit, the dynamic proximity operation is adopted.

Mode 2 dynamic proximity operation

Radware

The method of dynamic proximity has been patented, which can be combined according to the real location of the user or the round trip delay between LDNS and each site, hops, and the current load of each site (three conditions can be set to calculate the weight) to direct the user to the best site.

In order to avoid the access delay brought to users during dynamic calculation, the Radware device uses the calculation result of class C address to save the queried IP address, and directly invokes the checked and calculated ground fruit for users in the same class C address. In addition, you can manually set the retention time of the calculation results.

2.2.3 Health check

AppDirector-Global 's reliable health check can ensure that users get the best service site. AppDirector-Global can monitor the working status of the server on all protocol layers such as IP, TCP, UDP, application, and content. If a failure is found, the user is transparently redirected to the working service site. This ensures that users can always get the information they expect.

To ensure the normal operation of the service, AppDirector-Global monitors the working status of the entire path from the Web server, the middleware server to the back-end database server, ensuring that the servers on the entire data path are in a normal state. If there is a failed server, AppDirector-Global will not assign users to the server where the failure path occurred, thus ensuring transparent data integrity for users.

2.2.4 reliable guarantee of transaction integrity

Based on the DNS session persistence feature, AppDirector-Global ensures that users' same session requests are always maintained on the server at the same site.

In order to ensure that users will not be assigned to different servers by load balancers when accessing services with session continuity, AppDirector-Global can not only provide local load balancing, but also locate users' requests on the same server based on cookie,session,sourceIP and other ways.

2.2.5 full fault tolerance and redundancy

The configuration of AppDirector-Global provides full fault tolerance between devices to ensure maximum network availability. Two AppDirector-Global devices work in redundancy mode and check each other's working status through the network to ensure complete network availability for the applications they manage. They can work in "active-standby" mode or "active-active" mode, and in "active-active" mode, because both devices are working, the investment is protected to the maximum extent. And all the information can be mirrored between devices, providing transparent redundancy and full fault tolerance, ensuring that users can get the best service from click to content at any time.

2.2.6 ensure stable operation through normal exit service

When a server upgrade or system maintenance is needed, AppDirector ensures that a stable server is out of service to avoid service interruption. When a server is selected to exit service from the server, AppDirector will not assign any new users to that server. However, it can complete the service to the current user on the server where it wants to withdraw from the service. Thus, it ensures the high-quality service without interruption, as well as the simple management ability of the server group.

2.2.7 Intelligent server service recovery

When applying a restarted server to a service, it is important to avoid system failures caused by sudden traffic shocks on the new server. Therefore, when a new server is introduced into a server group, AppDirector will gradually increase the traffic allocated to that server until it reaches its full processing capacity. This not only ensures that the user can get uninterrupted service when the server exits the service, but also ensures that the server can get uninterrupted service during startup and at the beginning of the application.

2.2.8 optimizing server resources through load balancing

AppDirector performs complex load balancing algorithms that dynamically distribute load among multiple local and remote servers. These algorithms include loops, minimum number of users, minimum traffic, NativeWindowsNT, and custom agent support. In addition to these algorithms, AppDirector can also assign a configurable performance weighting to each server, thereby improving the performance of the server group.

2.2.9 Application switching

AppDirector determines traffic allocation based on IP address, application type, and content class. In this way, administrators can allocate different server resources for different types of applications. Application switching supports a variety of applications on different protocols, including TCP, UDP, IP, Telnet, Rshell, TFTP, streaming, passive FTP, HTTP, e-mail, DNS, VOIP and so on. Radware also designs special support features for applications that run on dynamic ports and require synchronization.

2.2.10 URL switching

AppDirector fully supports URL switching and distributes traffic based on URL and HTTP information. Each URL can be redirected to a server or load balanced across multiple servers to provide optimized Web switching performance. According to the information contained in the URL text, AppDirector can maintain customer persistence, thus ensuring the personalization of the content.

2.2.11 content exchange

Content exchange enables administrators to allocate server resources based on the content of the transaction. For example, CGI scripts can be located in a separate server group, and when a request for that content occurs, the session is redirected to one of the servers. AppDirecto-Global 's content exchange capability can widely support SSLID and Session ID, maintain customer persistence, ensure optimal traffic management and personalization of application content.

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