The New Network Load Balancer

As of September 7, 2017, Amazon introduced the Network Load Balancer (NLB) which is designed to handle tens of millions of requests per second while maintaining high throughput at ultra low latency. The Network Load Balancer is API-compatible with the Application Load Balancer, including full programmatic control of Target Groups and Targets.

Here is a list of the top features:

Static IP Addresses – Each Network Load Balancer provides a single IP address for each Availability Zone in its purview. If you have targets in us-east-1a and other targets in us-east-1c, the NLB will create and manage two IP addresses (one per AZ); connections to that IP address will spread traffic across the instances in all the VPC subnets in the AZ.

You can also specify an existing Elastic IP for each AZ for even greater control. With full control over your IP addresses, Network Load Balancer can be used in situations where IP addresses need to be hard-coded into DNS records, customer firewall rules, and so forth.

Zonality – The IP-per-AZ feature reduces latency with improved performance, improves availability through isolation and fault tolerance and makes the use of Network Load Balancers transparent to your client applications. Network Load Balancers also attempt to route a series of requests from a particular source to targets in a single AZ while still providing automatic failover should those targets become unavailable.

Source Address Preservation – With Network Load Balancer, the original source IP address and source ports for the incoming connections remain unmodified, so application software need not support X-Forwarded-For, proxy protocol, or other workarounds. This also means that normal firewall rules, including VPC Security Groups, can be used on targets.

Long-running Connections – NLB handles connections with built-in fault tolerance, and can handle connections that are open for months or years, making them a great fit for IoT, gaming, and messaging applications.

Failover – Powered by Route 53 health checks, NLB supports failover between IP addresses within and across regions.


Overall, this is a great choice for load balancing millions of TCP requests per second while maintaining high performance and low latency. It is optimized to handle sudden and volatile traffic patterns, while just using a single static address per AZ.

To see a side-by-side comparison of features for all of AWS ELBs up to now, look here:

Network Load Balancers are available as of now in all AWS commercial regions except China (Beijing), supported by AWS CloudFormation, Auto Scaling, and Amazon ECS.