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This article introduces the knowledge of "which parts of load balancing". In the operation of actual cases, many people will encounter such a dilemma. Then let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Load balancer (Server Load Balancer) is a traffic distribution control service that distributes access traffic to multiple backend CVMs (ECS instances) according to forwarding policies. Load balancing extends the service capability of the application and enhances the availability of the application.

Cloud load balancer virtualizes the added ECS instances into a high-performance and highly available application service pool by setting virtual service addresses, and distributes requests from clients to ECS instances in the CVM pool according to forwarding rules.

By default, the load balancer checks the health status of ECS instances in the CVM pool, automatically isolates abnormal ECS instances, eliminates a single point of failure of a single ECS instance, and improves the overall service capability of the application. In addition, load balancer also has the ability to resist DDoS attacks, which enhances the protection capability of application services.

component

Load balancing consists of the following three parts:

Load balancer instance (Server Load Balancer instances)

A load balancer instance is a running load balancing service that receives traffic and allocates it to the back-end server. To use the server load balancer service, you must create a load balancer instance and add at least one listener and two ECS instances.

Monitoring (Listeners)

Snooping is used to check client requests and forward them to the back-end server. Monitoring also performs a health check on the back-end server.

Back-end server (Backend Servers)

A set of ECS instances that receive front-end requests. You can add ECS instances to the server pool individually, or you can add and manage them in batches through virtual server groups or master / slave server groups.

As shown in the following figure, after the request from the client passes through the cloud load balancer instance, the listener will distribute the request to the ECS instance added at the backend for processing according to the configured listening rules.

Product advantage

High availability

Adopt full redundancy design, no single point, and support disaster recovery in the same city. Cross-region disaster recovery can be achieved with DNS, and the availability is as high as 99.95%.

Flexible expansion is carried out according to the application load, and the external service is not interrupted in the case of traffic fluctuation.

Low cost

Compared with the high investment of traditional hardware load balancing system, the cost can be reduced by 60%.

Safety

Aliyun makes a comprehensive optimization of Keepalived, the management software of open source four-tier load balancer LVS, so that the LVS-based four-tier load balancer has the ability of close to real-time defense. Combined with Cloud Shield, it can provide less than 5G anti-DDOS attack capability.

The seven-tier load balancing which uses Tengine as the basic module of load balancing has multi-dimensional CC attack defense capability.

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