Last Updated: Sep 25, 2017

  • Supported protocol

    Alibaba Cloud provides both layer-4 (TCP and UDP) and layer-7 (HTTP and HTTPS) load balancing services.

  • Health check

    Through health check on backend ECS instances, Server Load Balancer can automatically block abnormal ECS instances and distribute requests to them when they become normal.

  • Session persistence

    Server Load Balancer supports session persistence. You can set listening rules to forward a session request from a client to the same backend ECS instance during the session lifecycle.

  • Scheduling algorithm

    Server Load Balancer supports the following scheduling algorithms:

    • Round robin

      Requests are distributed across the backend ECS servers sequentially.

    • Weighted round robin (WRR)

      You can set a weight for each backend server. Servers with higher weights receive more requests than those with lower weights.

    • Weighted least connections (WLC)

      In addition to weight set for each backend ECS server, the number of connections to the client is also considered. The servers with a higher weight value will receive a larger percentage of live connections at any one time. If weights are the same, the system directs network connections to the server with the least established connections.

  • Domain name/URL-based forwarding

    For Layer-7 (HTTP and HTTPS) protocols, Server Load Balancer forwards traffic to different VServer groups based on domain names or URLs.

  • Multiple zones

    To provide a more stable and reliable load balancing service, Server Load Balancer has deployed multiple zones in most regions. If the primary zone becomes abnormal, the backup zone automatically takes over the load balancing service from the faulty zone.

  • Access control

    You can set a whitelist to control which IP addresses can access Server Load Balancer.

  • Security

    Server Load Balancer supports application firewalls and HTTP flood protection. Combined with Alibaba Cloud Security, the system can defend against DDoS attacks under 5 Gbps.

  • Certificate management

    Server Load Balancer service provides Certificate Management for the HTTPS protocol listening. With Certificate Management, you do not need to upload certificates to backend ECS instances. Deciphering is performed on Server Load Balancer to reduce the CPU overheads of backend ECS instances.

  • Bandwidth control

    You can set the bandwidth peak for each listener based on the service that the application can provide.

  • Instance type

    You can choose to create an Internet or Intranet Server Load Balancer service. The system will assign a public IP address or private IP address accordingly.

  • Monitoring

    With the Monitor function, you can get the real-time statuses of your Server Load Balancer.

  • Management methods

    You can manage Server Load Balancer instances through various methods, such as the Server Load Balancer console, Open API, and SDK.

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