Alb vs. NLB

Attribute	Alb	NLB
Definition	Application Load Balancer	Network Load Balancer
Layer	Layer 7 (Application layer)	Layer 4 (Transport layer)
Protocols Supported	HTTP, HTTPS, WebSocket	TCP, TLS, UDP
Health Checks	HTTP, HTTPS, TCP	TCP, TLS, UDP
Target Groups	IP address, instance ID, Lambda function	IP address, instance ID

Introduction

When it comes to load balancing solutions, two popular options are Application Load Balancer (ALB) and Network Load Balancer (NLB). Both of these services are offered by Amazon Web Services (AWS) and are designed to distribute incoming traffic across multiple targets, such as EC2 instances, containers, or IP addresses. While they serve a similar purpose, there are key differences in their attributes that make them suitable for different use cases.

Performance

One of the main differences between ALB and NLB is their performance characteristics. ALB operates at the application layer (Layer 7) of the OSI model, meaning it can inspect the content of the incoming traffic and make routing decisions based on factors such as URL path or host header. This allows ALB to provide advanced routing capabilities and support for features like content-based routing and path-based routing. On the other hand, NLB operates at the transport layer (Layer 4) and focuses on routing traffic based on IP protocol data. This makes NLB more suitable for high-performance, low-latency applications that require efficient handling of TCP and UDP traffic.

Health Checks

Another important attribute to consider when comparing ALB and NLB is their health check mechanisms. ALB supports both HTTP and HTTPS health checks, allowing it to monitor the health of its targets by sending requests to specific URLs and checking for expected responses. This makes ALB well-suited for web applications that require detailed health monitoring and automatic failover capabilities. In contrast, NLB supports TCP health checks, which are more lightweight and suitable for applications that do not require detailed application-level health monitoring. NLB's TCP health checks are faster and consume fewer resources compared to ALB's HTTP/HTTPS health checks.

Target Groups

ALB and NLB also differ in their support for target groups. ALB allows you to define target groups based on attributes such as path patterns, host headers, or query strings, enabling you to route traffic to different sets of targets based on specific criteria. This flexibility makes ALB a great choice for microservices architectures and applications with complex routing requirements. On the other hand, NLB supports target groups based on IP addresses, making it more suitable for applications that require direct IP routing without the need for additional routing logic at the application layer.

Security

Security is a critical consideration when choosing between ALB and NLB. ALB provides built-in support for SSL termination, allowing you to offload SSL/TLS encryption and decryption at the load balancer level. This simplifies the management of SSL certificates and improves the performance of your backend servers. Additionally, ALB supports Web Application Firewall (WAF) integration, enabling you to protect your applications from common web exploits and attacks. NLB, on the other hand, does not provide native support for SSL termination or WAF integration. If your application requires advanced security features, ALB may be the better choice.

Cost

Cost is another factor to consider when evaluating ALB and NLB. ALB pricing is based on the number of load balancer capacity units (LCU) used per hour, as well as data processing charges for traffic processed by the load balancer. NLB pricing is based on the number of load balancer hours used, as well as data processing charges similar to ALB. In general, ALB tends to be more cost-effective for applications that require advanced routing capabilities and detailed health monitoring, while NLB may be a more economical choice for applications that prioritize high-performance TCP and UDP traffic handling.

Conclusion

In conclusion, ALB and NLB are both powerful load balancing solutions offered by AWS, each with its own set of attributes and use cases. ALB excels in applications that require advanced routing capabilities, detailed health monitoring, and SSL termination, making it a great choice for web applications and microservices architectures. NLB, on the other hand, is well-suited for high-performance applications that require efficient handling of TCP and UDP traffic, as well as direct IP routing without the need for complex application-level routing logic. By understanding the key differences between ALB and NLB, you can choose the right load balancing solution that best fits your specific requirements and budget.