Load Balancer

Load balancing algorithms are used to distribute incoming network traffic across multiple servers or nodes in order to optimize resource utilization, improve performance, and ensure high availability. Here are brief descriptions of some commonly used load balancing algorithms:

  1. Round Robin: In the round-robin algorithm, traffic is distributed equally across all servers in a round-robin fashion. Each server takes turns handling requests in a cyclical order.

  2. Least Connections: The least-connections algorithm assigns incoming traffic to the server with the fewest active connections. This helps distribute traffic to underutilized servers and ensures that heavily loaded servers do not become overwhelmed.

  3. IP Hash: In the IP hash algorithm, the source IP address of the incoming traffic is used to determine which server to send the traffic to. This is useful when you want to maintain session persistence for a particular client IP address.

  4. Random: The random algorithm assigns traffic to servers randomly, without taking into account the load on each server. This approach can work well for small, homogeneous server clusters.

  5. Weighted Round Robin: In the weighted round-robin algorithm, each server is assigned a weight that reflects its processing capacity. Traffic is then distributed across servers in proportion to their weights, so that more traffic is sent to higher-capacity servers.

  6. Weighted Least Connections: The weighted least-connections algorithm takes into account both the server's capacity (as in weighted round robin) and the number of active connections (as in least connections) to determine which server to send traffic to.

  7. Dynamic: In a dynamic load balancing algorithm, the server's capacity is continuously monitored and updated in real-time based on the current load. This allows the load balancer to adjust the traffic distribution based on the actual capacity of each server.

In Kubernetes, there are multiple ways to distribute incoming network traffic to the backend pods of a service, such as Round Robin or Least Connection. Kubernetes uses a default algorithm called IPVS (IP Virtual Server) to balance the incoming network traffic.

IPVS is a kernel-level load balancer that is built into the operating system, which is responsible for routing network traffic between nodes in a Kubernetes cluster. The load balancer algorithm used by IPVS can be configured to distribute traffic to backend pods based on different criteria, such as the number of active connections to a pod or the processing capacity of the pod.

To manage the IPVS load balancing in Kubernetes, there is a component called kube-proxy, which runs on each node in the cluster. Kube-proxy monitors the Kubernetes API server to determine the configuration of services and their associated pods, and then creates IPVS rules and virtual servers to direct the incoming network traffic to the appropriate backend pods.

In summary, Kubernetes uses IPVS as the default load balancing algorithm to distribute network traffic to the backend pods of a service. This is managed by a component called kube-proxy, which dynamically creates IPVS rules and virtual servers to route the traffic.