Know different Load Balancers in AWS

A quick post about different types of load balancers in AWS and the difference between them.

AWS offers a load balancing feature under EC2 compute service. It offers basically 4 types of load balancers :

1. Application Load Balancer
2. Network Load Balancer
3. Gateway Load Balancer
4. Classic Load Balancer

We will quickly go through them one by one and finally compare them with each other.

Application Load Balancer

• It’s a Layer 7 load balancer. Operates at the application layer.
• Aimed to handle HTTP and HTTPS traffic
• It is capable of routing based on path patterns.
• SSL can be offloaded to it. Supports SNI.
• Even authentications can be offloaded to it.
• Targets can be EC2, Lambda, and IP addresses.
• Step by step ALB creation

Network Load Balancer

• It’s a layer 4 Load Balancer. Operates at the transport layer.
• Aimed to handle TCP, UDP, and TLS traffic
• Uninterrupted end to end encryption till target
• Ultra-low latency load balancers capable of handling millions of requests per second.

Gateway Load Balancer

• It’s a Layer 3 Load Balancer. Operates at the network layer.
• Aimed to handle virtual appliances traffic on GENEVE protocol.
• Scale virtual appliances like Firewalls, IDP, etc. using this LB

Classic Load Balancer

• It’s a combination of ALB and NLB offered by AWS formerly (with reduced features).
• New deployments should not be using it.
• Its existence is only for compatibility for old EC2-Classics running customers.

Lets compare all 4 Elastic Load Balancers side by side –

	ALB	NLB	GLB	CLB
OSI model layer	7	4	3	7 and 4
Protocol supported	HTTP, HTTPS	TCP, UDP, TLS	GENEVE	HTTP, HTTPS, TCP
Supports static IP for ELB	No, only DNS name	Yes	No	No, only DNS name
SSL offloading	Yes	Yes (TLS termination)	No	Yes
SNI support	Yes	Yes	No	No
Authentication offloading	Yes	No	No	No
End to end encryption	No if using SSL offloading	Yes	No	Yes
Sticky sessions	Yes	Yes	Yes	Yes
Path patterns	Yes
Cross zone load balancing	Enabled by default	Yes	Yes	Disabled. Enable it manually
Type of registered targets	Instance, Lambda, IP	Instance, IP	Instance, IP	Instance,IP
Use cases	Websites, web applications	Application requiring low latency load balancing	Load balancing or scaling virtual appliances for IDP, firewall etc.	Web applications.

I mentioned the commonly used features comparison above. Amazon published a very good comparison of all load balancers on this page.