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5.2.3. Load Balancer Cost Considerations

Optimizing load balancer costs involves selecting the appropriate ELB type and efficiently utilizing its resources, ensuring traffic distribution and high availability at the lowest sustainable price.

Scenario: You need to provision a load balancer for an application. One option is a web application with complex HTTP/S routing. Another is a high-throughput gaming server that uses TCP/UDP protocols. You need to choose the most cost-effective load balancer type for each.

Elastic Load Balancing (ELB) is crucial for high availability and scalability, but its costs can vary significantly based on the chosen load balancer type and traffic patterns. Network specialists must consider cost implications.

Key Load Balancer Cost Considerations:
  • Pricing Components:
    • Hourly Charge: Per hour the load balancer is provisioned.
    • LCUs (Load Balancer Capacity Units): For ALB, usage-based charges based on new connections, active connections, processed bytes, and rule evaluations.
    • LCU (Network Load Balancer): For NLB, based on new TCP connections, active TCP connections, processed bytes, and flow duration.
  • ALB vs. NLB Cost:
    • ALB: Generally more expensive per LCU due to Layer 7 processing, but cost-effective for complex routing.
    • NLB: Often more cost-effective for high-throughput, simple Layer 4 traffic due to lower LCU costs.
  • Gateway Load Balancer (GLB): Billed hourly and by LCU (based on new flows, active flows, and processed bytes). Consider the cost of underlying network virtual appliances.
  • Traffic Patterns: Costs are heavily influenced by the volume of traffic (new connections, active connections) and the amount of data processed.
  • Idle Load Balancers: Even idle load balancers incur hourly charges. Delete unused ones.
Practical Implementation: Deleting an Unused Load Balancer (CLI)
# 1. List all load balancers to identify unused ones
aws elbv2 describe-load-balancers

# 2. Delete the load balancer by ARN
aws elbv2 delete-load-balancer --load-balancer-arn arn:aws:elasticloadbalancing:us-east-1:123456789012:loadbalancer/app/my-unused-alb/abcdef1234567890

⚠️ Common Pitfall: Not deleting unused load balancers. Even if no traffic is flowing, they still incur hourly charges.

Key Trade-Offs:
  • Layer 7 Features (ALB) vs. Raw Performance/Cost (NLB): ALBs offer more features but can be more expensive for high-volume, simple traffic. NLBs are more cost-effective for raw Layer 4 throughput.

Reflection Question: How does optimizing load balancer costs by selecting the appropriate ELB type (ALB vs. NLB) and efficiently utilizing its resources (e.g., managing traffic patterns) fundamentally ensure traffic distribution and high availability at the lowest sustainable price?