AWS Network Load Balancer (NLB) – Key Concepts & Use Cases

In this lesson, we explored the Network Load Balancer (NLB), which operates at Layer 4 (TCP/UDP) of the OSI model and is designed for high-performance, low-latency workloads.

1. Key Features of Network Load Balancer

• Layer 4 Load Balancer: Unlike the Application Load Balancer (ALB), which works at Layer 7 (HTTP/S), the NLB handles TCP and UDP traffic.
• Extreme Performance: Supports millions of requests per second with ultra-low latency.
• Static IPs: Assigns one static IP per Availability Zone (AZ), and you can associate Elastic IPs for each AZ.
• Not in Free Tier: Unlike ALB, using NLB is not covered under AWS Free Tier.

When to Use Network Load Balancer?

• TCP/UDP Workloads (e.g., VoIP, gaming, or databases like MySQL).
• High-performance, high-throughput applications.
• Scenarios requiring static IPs for whitelisted access.

2. How Network Load Balancer Works

Target Groups in NLB

NLB routes traffic to target groups, which can contain:

1. EC2 Instances – Directly forwards TCP/UDP traffic.
2. IP Addresses – Must be private IPs, useful for hybrid architectures.
3. Other AWS Load Balancers – Can be placed in front of an ALB for combining static IPs with ALB’s Layer 7 rules.

💡 Example Use Case: