Load balancing is an essential technique in cloud computing that distributes incoming network traffic across multiple servers to ensure no single server bears too much demand. This improves application responsiveness and increases availability. Amazon Web Services (AWS), Google Cloud Platform (GCP), and Microsoft Azure all offer various load balancing services that use different algorithms to distribute traffic. Here’s an overview of the commonly used load balancing algorithms in each platform:
AWS Load Balancing Algorithms
AWS offers three types of load balancers: Classic Load Balancer, Application Load Balancer, and Network Load Balancer. Each supports different algorithms:
- Round Robin: This is the simplest form of load balancing, used by the Classic Load Balancer. It distributes incoming requests sequentially among all servers.
- Least Outstanding Requests: Used by the Application Load Balancer, this algorithm directs new requests to the server with the fewest active connections. This is suitable for situations where request load is uneven.
- Flow Hash: Utilized by the Network Load Balancer, this algorithm directs all packets of a flow (a sequence of packets from the same source to the same destination) to the same target based on a hash of the flow fields.
GCP Load Balancing Algorithms
Google Cloud offers various load balancing options such as HTTP(S) Load Balancing, TCP/UDP Load Balancing, and Internal Load Balancing. Key algorithms include:
- Round Robin: Commonly used in TCP/UDP Load Balancing, distributing requests equally among all available instances.
- Weighted Round Robin: An enhancement over the basic Round Robin, this allows assigning weights to instances based on their capacity.
- Maglev: Used in HTTP(S) Load Balancing, this algorithm efficiently handles massive amounts of traffic without any single point of failure. It uses a consistent hashing mechanism to achieve high availability.
Azure Load Balancing Algorithms
Azure provides Load Balancer and Application Gateway as its primary load balancing services. It supports several algorithms:
- Hash-based Distribution: The basic algorithm used by Azure’s Load Balancer, which maps traffic to available servers based on a hash of some part of the request (like IP address or port number).
- Round Robin: This is used in conjunction with hash-based distribution for distributing incoming connections across all servers in a backend pool.
- Least Requests: An algorithm used by Azure Application Gateway that routes traffic to the backend server with the fewest active requests.
- Session Persistence (Sticky Sessions): Azure Application Gateway can also use session persistence, where client requests are routed to the same server based on the client’s IP address or session cookie.
These algorithms are selected based on the specific requirements of the application, such as whether the priority is on distributing traffic evenly, handling persistent sessions, or managing variable request loads efficiently. Each cloud provider offers tools and settings that allow customization of the load balancing behavior to best fit different application scenarios.