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Server Load Balancer:Enable bandwidth sharing among listeners of a CLB instance

最終更新日:Feb 06, 2024

The bandwidth of a Classic Load Balancer (CLB) instance is limited. If services with different priorities are deployed on backend servers, you can reserve sufficient bandwidth for business-critical services. Other services can compete for the remaining bandwidth. This solution improves service availability and stability. All listeners of a CLB instance can share the bandwidth of the CLB instance.

How bandwidth sharing works

For example, you purchased a CLB instance whose maximum bandwidth is 10 Mbit/s. Listener A, Listener B, and Listener C are added to the CLB instance.

The maximum bandwidth value of Listener A is set to 4 Mbit/s. No maximum bandwidth values are specified for Listener B or Listener C.

The following scenarios describe how bandwidth sharing works:

  • If Listener A and Listener C remain idle, Listener B can consume at most 6 Mbit/s of bandwidth because 4 Mbit/s of bandwidth is reserved for Listener A.

  • If Listener C remains idle, and Listener B forwards a high volume of network traffic that requires more than 6 Mbit/s of bandwidth, some packets are dropped by Listener B. Listener A does not drop packets because 4 Mbit/s of bandwidth is reserved for Listener A and it consumes less than 4 Mbit/s of bandwidth.

  • If Listeners A, B, and C forward a high volume of network traffic, Listener B and Listener C compete for the remaining 6 Mbit/s of bandwidth. In this case, Listener A can still reach the maximum bandwidth, which is 4 Mbit/s. If the volume of network traffic forwarded by Listener B and Listener C is the same, each of Listener B and Listener C consumes 50% of the remaining bandwidth.

  • If the total 10 Mbit/s of bandwidth is allocated to Listener A and Listener B, Listener C drops packets and becomes unavailable because Listener C is not allocated with bandwidth.

Therefore, bandwidth throttling for listeners can ensure that business-critical services can be allocated with sufficient bandwidth resources. You do not need to specify a maximum bandwidth for listeners that are used by non-business-critical services. The listeners can compete for the remaining bandwidth resources.

Procedure for enabling bandwidth throttling

You can configure bandwidth throttling when you create a listener for your CLB instance. In the Protocol & Listener step, click Modify on the right side of Advanced Settings. Then, select Bandwidth Throttling for Listeners.

  • After bandwidth throttling is enabled for a listener, the bandwidth of the listener is limited. The sum of the bandwidth of all listeners cannot exceed the maximum bandwidth of the CLB instance.

  • After bandwidth throttling is disabled for a listener, the bandwidth of the listener is not limited. All listeners of the CLB instance share the bandwidth of the CLB instance.

References

After you create a CLB instance, you can adjust the maximum bandwidth of the CLB instance by modifying the configurations of the CLB instance. For more information, see Modify the configurations of pay-as-you-go CLB instances.