Modern Load Balancing: ALB vs NLB vs Envoy Gateway?

In modern microservices architectures, Traffic Management is one of the most critical components for application performance and security. When working on AWS, we usually encounter Application Load Balancer (ALB) and Network Load Balancer (NLB) options. However, with the rise of Kubernetes, new generation solutions like Envoy Gateway have also entered the equation. So which one should you choose and when?

In this guide, we will examine the differences and usage scenarios of these technologies. You can get support from our Kubernetes Consultancy and AWS Consultancy services to manage your complex network structures.

1. Application Load Balancer (ALB): Master of the Application Layer

ALB works at layer 7 of the OSI model (L7 - Application Layer). It understands HTTP/HTTPS traffic, looks at its content, and makes decisions accordingly.

• When to Use? Web applications, microservices, containers.
• Features:
  • Content-Based Routing: Can route /api requests to one service and /images requests to another.
  • SSL Termination: Easily handles certificate management (ACM integration).
  • WAF Integration: Provides security by working with AWS WAF.
• Disadvantage: Does not support TCP/UDP traffic (e.g., database connections or game servers).

2. Network Load Balancer (NLB): Speed and Performance Beast

NLB works at layer 4 (L4 - Transport Layer). It does not look at the content of the packet, it routes only based on IP and Port information.

• When to Use? Very high traffic systems (millions of requests/second), TCP/UDP applications, situations requiring static IP.
• Features:
  • Ultra Low Latency: Much faster than ALB.
  • Static IP: Offers a fixed IP address (ALB does not, it gives a DNS name).
• Disadvantage: Cannot read HTTP headers, cannot perform smart routing.

3. Envoy Gateway: Kubernetes' New Star

Envoy Proxy is a high-performance proxy designed for Cloud Native applications. Envoy Gateway makes it easy to use this as a Kubernetes entry point (Ingress/Gateway API).

• Why Envoy? AWS ALB/NLB are great services, but sometimes they may not suffice for the dynamism of the Kubernetes world, or a cloud-agnostic solution may be needed.
• Advantages:
  • Advanced Traffic Management: Natively supports complex scenarios like Canary deployment, Blue/Green deployment, Traffic Mirroring.
  • Observability: Offers very detailed metrics and logs.
  • Platform Independent: Works with the same configuration both on AWS and in your own data center.

The Moment of Decision: Which One?

• If you have a simple web application and use AWS: ALB.
• If you are setting up a game server or database proxy receiving millions of requests per second: NLB.
• If you are managing complex microservice traffic on Kubernetes, doing Canary releases, and want detailed metrics: Envoy Gateway.

Often the best architecture is to use them together. For example, it is a common practice to receive traffic from the outside world with NLB, forward it to the internal Kubernetes cluster, and manage the distribution within the cluster with Envoy (Ingress Controller).