Load Balancer Types
Classifications of load balancers by operation layer: L4 transport layer and L7 application layer.
Definition
Load balancers operate at different OSI model layers with different capabilities. Layer 4 (transport layer) load balancers route traffic based on IP addresses and TCP/UDP ports with minimal processing, providing high throughput. Layer 7 (application layer) load balancers inspect HTTP headers, URLs, and content to make intelligent routing decisions, enabling path-based routing, A/B testing, authentication offload, and content-based switching. Hardware load balancers (F5), software load balancers (HAProxy, NGINX), and cloud load balancers (AWS ALB/NLB) serve different scales.
Example
“An AWS Application Load Balancer (Layer 7) routes /api requests to the backend microservice cluster and /static requests to an S3 bucket, while an AWS Network Load Balancer (Layer 4) handles millions of TCP connections per second for the gaming server.”
Synonyms
- L4 L7 load balancing
- network load balancer
- application load balancer
Images
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Related Terms
- load-balancer
- osi-model
- http
- microservices