Using Network Load Balancer (NLB) with ECS - AWS ECS Tutorial

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The Network Load Balancer (NLB) is a powerful load balancing service provided by Amazon Web Services (AWS) that allows you to distribute traffic to your containerized applications in Amazon Elastic Container Service (ECS) at the network level. NLB operates at the Transport Layer (Layer 4) of the OSI model, providing ultra-low latency and high throughput. This tutorial will guide you through the process of using a Network Load Balancer with ECS to achieve efficient and scalable traffic distribution.

Using Network Load Balancer (NLB) with ECS

To use a Network Load Balancer (NLB) with Amazon ECS, follow these steps:

  1. Create an NLB: Set up an NLB in the desired Amazon Virtual Private Cloud (VPC) and configure the necessary settings, such as listeners and target groups.
  2. Create a target group: Specify the ECS service as the target type and configure the target group to register the tasks in the ECS service.
  3. Configure health checks: Define health check settings for the target group to ensure that only healthy tasks receive traffic.
  4. Associate the target group with the NLB: Connect the target group to the NLB to enable traffic routing.
  5. Test the NLB: Verify that the NLB is distributing traffic evenly across the ECS tasks and that the health checks are functioning as expected.

Example: Configuring an NLB

Here's an example of configuring a Network Load Balancer (NLB) using AWS CLI commands:

aws elbv2 create-load-balancer --name my-nlb --type network --subnets subnet-12345678 --security-groups sg-12345678

aws elbv2 create-target-group --name my-target-group --protocol TCP --port 80 --target-type ip --vpc-id vpc-12345678

aws elbv2 create-listener --load-balancer-arn arn:aws:elasticloadbalancing:us-west-2:123456789012:loadbalancer/net/my-nlb/1234567890123456 --protocol TCP --port 80 --default-actions Type=forward,TargetGroupArn=arn:aws:elasticloadbalancing:us-west-2:123456789012:targetgroup/my-target-group/1234567890123456
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Common Mistakes

  • Not configuring health checks properly, leading to incorrect routing decisions and potential downtime.
  • Forgetting to update the NLB listener or target group configuration when making changes to the ECS service or task definitions.
  • Overlooking security group rules or NACL configurations that may block traffic to the NLB or ECS tasks.
  • Ignoring SSL/TLS termination settings or not properly configuring encryption for secure traffic.
  • Not considering the scalability and performance requirements when selecting the NLB instance size.

Frequently Asked Questions

  1. Can I use NLB with both EC2 and Fargate launch types in ECS?

    Yes, NLB is compatible with both EC2 and Fargate launch types in Amazon ECS.

  2. Can I configure SSL/TLS termination with NLB for secure traffic?

    No, NLB operates at the transport layer and does not support SSL/TLS termination. You can use an SSL/TLS termination proxy in front of the NLB to handle encryption.

  3. Can I use NLB for UDP-based applications in ECS?

    Yes, NLB supports both TCP and UDP protocols, making it suitable for UDP-based applications in Amazon ECS.

  4. Can I use NLB to distribute traffic to tasks in multiple availability zones?

    Yes, NLB can distribute traffic across ECS tasks running in different availability zones within a region.

  5. What is the difference between NLB and ALB in ECS?

    NLB operates at the transport layer and provides high-performance load balancing, while ALB operates at the application layer and offers advanced features like content-based routing and HTTP/2 support.


Using a Network Load Balancer (NLB) with Amazon Elastic Container Service (ECS) allows you to efficiently distribute traffic to your containerized applications. By following the step-by-step guide, avoiding common mistakes, and understanding the FAQs, you can successfully configure an NLB and leverage its high-performance load balancing capabilities to enhance the availability and scalability of your ECS tasks and services.