Active/Passive

Active/Passive load balancing is a load balancing configuration where multiple servers or resources are organized in a redundant setup, but only one server is actively handling incoming network traffic while the others remain in a standby or passive state. The active server actively serves client requests, while the passive servers remain idle and are ready to take over the workload in case the active server fails or becomes unavailable.

How Active/Passive Load Balancing Works

In an Active/Passive load balancing configuration, the load balancer routes all incoming traffic to the active server. The active server is fully operational and handles all client requests. Meanwhile, the passive servers are configured identically to the active server but remain idle and do not participate in processing client requests.

If the active server experiences a failure or becomes unavailable, the load balancer detects the issue and triggers a failover mechanism. The failover process redirects the incoming traffic to one of the passive servers, which takes over the role of the active server. This ensures continuity of service and prevents service interruptions.

Benefits of Active/Passive Load Balancing

Active/Passive load balancing offers several benefits:

• High Availability: With an active server and passive backup servers, Active/Passive load balancing provides high availability. In case of server failure, the passive server can quickly take over, minimizing downtime.
• Reliability: Active/Passive load balancing ensures that at least one server is always available to handle client requests, improving the reliability of the service.
• Simple Management: Managing a smaller number of active servers is often simpler than managing multiple actively participating servers in Active/Active load balancing.

Considerations for Active/Passive Load Balancing

While Active/Passive load balancing provides high availability, there are some considerations to keep in mind:

• Resource Utilization: Only the active server processes client requests, which may result in underutilization of passive servers during normal operation.
• Failover Time: The time taken for the failover process to redirect traffic to a passive server can result in brief service interruption.
• Cost: Active/Passive load balancing requires additional hardware and resources for the passive servers, which may increase costs.

Conclusion

Active/Passive load balancing provides high availability and reliability by using redundant servers where one is active and the others remain in standby mode. While it may have some resource utilization and cost considerations, Active/Passive load balancing remains a popular choice for ensuring continuous service and minimizing downtime in critical applications and systems.