A load balancer is a device that acts as a reverse proxy and distributes network or application traffic across a number of servers.
a reverse proxy is a type of proxy server that retrieves resources on behalf of a client from one or more servers.
Load balancers are generally grouped into two categories: Layer 4 and Layer 7.
Layer 4 : Load balancers act upon data found in network and transport layer protocols (IP, TCP, FTP, UDP).
Layer 7: Load balancers distribute requests based upon data found in application layer protocols such as HTTP.
Load Balancing Algorithm
a reverse proxy is a type of proxy server that retrieves resources on behalf of a client from one or more servers.
Load balancers are generally grouped into two categories: Layer 4 and Layer 7.
Layer 4 : Load balancers act upon data found in network and transport layer protocols (IP, TCP, FTP, UDP).
Layer 7: Load balancers distribute requests based upon data found in application layer protocols such as HTTP.
Load Balancing Algorithm
Requests are received by both types of load balancers and they are distributed to a particular server based on a configured algorithm. Some industry standard algorithms are:
- Round robin
- Weighted round robin
- Least connections
- Least response time
Layer 7 Load Balancing
Layer 7 load balancers can further distribute requests based on application specific data such as HTTP headers, cookies, or data within the application message itself, such as the value of a specific parameter.
Load balancers ensure reliability and availability by monitoring the "health" of applications and only sending requests to servers and applications that can respond in a timely manner.
No comments:
Post a Comment