What is Elastic Load Balancer in AWS
Like other load balancers, Elastic Load Balancer(ELB) also receives incoming traffic from the clients and distributes it among multiple instances(Servers).
Elastic Load Balancer is used to make an application highly available. Elastic Load Balancer continuously does a health check of all instances and routes the traffic to only healthy instances.
Elastic Load Balancers are of three types:
1) Classic Load Balancer (CLB)
2) Application Load Balancer (ALB)
3) Network Load Balancer (NLB)
Also Read: AWS EBS Volume snapshot backup and restore
Classic Load Balancer(CLB)
Classic Load Balancer is used to distribute TCP/SecureTCP and HTTP/HTTPS traffic. It provides basic load balancing and simply distribute the traffic among multiple instances having singe URL.
We cannot do path based and host based routing using this load balancer.
Path based routing – It allows us to route a traffic to an instance serving a particular path like devopsmyway.com/windows-tutorial or devopsmyway.com/linux-tutorial.
Host based routing– It allows us to route a traffic to an instance serving a particular host like windows.devopsmyway.com or linux.devopsmyway.com.
In other words , Classic load balancer can distribute the traffic when all the instances serving one URL like devopsmyway.com.It cannot route traffic when instances serving different path like devopsmyway/windows-tutorial and devopsmyway/linux-tutorial .It also cannot route traffic when instances serving different hosts like windows.devopsmyway.com and linux.devopsmyway.com.
Application Load Balancer(ALB)
Application Load Balancer is used to distribute HTTP/HTTPS traffic only.
We can do path based and host based routing using this load balancer.
In other words, Application load balancer can distribute the incoming traffic when some instances serving different path like devopsmyway.com/windows-tutorial and devopsmyway.com/linux-tutorial or different hosts like windows.devopsmyway.com and linux.devopsmyway.com.
Network Load Balancer(NLB)
Network Load Balancer is used to distribute TCP, TLS and UDP traffics only.
This load balancer is capable to handle sudden spike on the website.When one instance become slow it routes the traffic to another healthy instances.
In my next blog I will share you how to create Elastic Load Balancers in AWS.I hope you enjoyed this tutorial and learned about AWS Elastic Load Balancer. If you think this is really helpful, please do share my website https://devopsmyway.com to others as well. Also, please give your valuable feedback in the comment box.