How do I configure LB for an Intranet or a WAN?

When creating LB, you can select Intranet or WAN in the network type field. If you select Intranet, the system will allocate an Intranet VIP. If you select WAN, you can select an existing EIP in the next field. If an Intranet load balancer is bound with a WAN EIP, it can be used as a WAN load balancer. LB supports both Intranet and WAN access.

Can I adjust the number of backend servers when a load balancer is running?

You can adjust the number of backend servers associated with a load balancer when it is running. You can also change the type of backend servers according to your service requirements. To ensure service stability, ensure that health checks are enabled for the load balancer and that at least one healthy backend server is associated with the load balancer.

How do I check if session persistence failed to take effect for ELB?

Check whether session persistence is enabled for the backend server group.
Check the health check result of the backend ECS. If the health check result is Unhealthy, traffic is routed to other backend ECSs and session persistence become invalid.
If you select the source IP hash algorithm, check whether the IP address of the request changes before the ELB receives the request.
If session persistence is enabled for an HTTP or HTTPS listener, check whether the request carries a cookie. If there is a cookie, check whether the cookie value changed (because session persistence at Layer 7 is based on cookies).

What are the relationships between LB algorithms and session persistence types for a listener?

Assign policy	Session persistence type	L4(TCP/UDP)	L7(HTTP/HTTPS)
Weighted Round Robin	Source IP address	Supported	Not supported
	Load Balancer cookie	N/A	Supported
	Application program cookie	N/A	Supported
Weighted Least Connection	Source IP address	Supported	Not supported
	Load Balancer cookie	N/A	Supported
	Application program cookie	N/A	Supported
Source IP Address	Source IP address	N/A	Not supported
	Load Balancer cookie	N/A	Not supported
	Application program cookie	N/A	Not supported

General recommendation: Generally, the round robin algorithm is recommended. Session persistence at Layer 4 uses source IP addresses and session persistence at Layer 7 uses load balancer cookies.

Can I modify the bandwidth of ELB?

You can adjust the bandwidth of WAN ELB, and modify the bound IPv4 or IPv6 bandwidth at the LB instance.

Elastic Load Balancing

Operation