ALB vs NLB vs GWLB

~10 min read

Three load balancer types operating at different layers, for different traffic shapes.

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Key points

  • ALB (Layer 7): content-aware routing by path/host, the default for HTTP web apps and APIs
  • NLB (Layer 4): extreme throughput, preserves client source IP, supports static IPs, for TCP/UDP/non-HTTP
  • GWLB: transparently inserts third-party network appliances into a traffic path
  • ALB replaces the client's source IP; recover it via the X-Forwarded-For header if your app needs it