Lecture Note 11 - Load Balancing Concepts PDF

LECTURE NOTE 11: LOAD BALANCING CONCEPTS 1. Introduction to Load Balancing a) Definition of Load Balancing: Load balancing is the process of distributing network traffic or computational workload across multiple servers, links, or devices.  Ensures no single reso...

LECTURE NOTE 11: LOAD BALANCING CONCEPTS 1. Introduction to Load Balancing a) Definition of Load Balancing: Load balancing is the process of distributing network traffic or computational workload across multiple servers, links, or devices.  Ensures no single resource is overwhelmed while others remain underutilized. b) Purpose of Load Balancing:  Optimize resource usage.  Minimize latency and response time.  Provide high availability and fault tolerance. c) Where Load Balancing is Applied: In Networks: Across multiple links, routers, or switches. In Servers: Among servers in data centers or web applications. Cloud Environments: Distributing tasks among cloud-based resources. d) Load Balancer Types:  Hardware Load Balancers: Dedicated devices for traffic management.  Software Load Balancers: Applications like HAProxy or NGINX.  Cloud-Based Load Balancers: Services like AWS Elastic Load Balancer (ELB). 2. Importance of Load Balancing in Networking a) Improved Performance:  Distributes traffic to prevent network congestion.  Ensures optimal usage of available bandwidth and resources. b) Redundancy and Fault Tolerance: Automatically reroutes traffic in case of a link or server failure. Enhances the reliability of applications and services. c) Enhanced Scalability: Allows networks and applications to handle increasing loads by adding more resources seamlessly. d) Resource Optimization:  Ensures that no single device or link is overburdened while others remain idle. e) Minimized Downtime:  Load balancers provide continuous availability by detecting and bypassing failed components. f) Security Benefits:   Protects against Distributed Denial of Service (DDoS) attacks by distributing malicious traffic.  Enables the use of secure connections and firewalls in a balanced network. 3. Load Balancing Algorithms and Techniques a) Static Load Balancing: Pre-determined rules are used to distribute traffic or workloads. Examples:  Round Robin: Traffic is distributed evenly in a sequential manner.  Weighted Round Robin: Traffic is distributed based on pre-assigned weights to paths or servers. b) Dynamic Load Balancing:  Adjusts traffic distribution in real time based on current network conditions. Examples:  Least Connections: Traffic is sent to the server or link with the fewest active connections.  Least Response Time: Directs traffic to the resource with the fastest response time.  Adaptive Load Balancing: Uses algorithms that consider multiple metrics (e.g., load, response time, and health). c) Equal-Cost Load Balancing: Used in routing protocols like OSPF or RIP. Distributes traffic across paths with equal metrics or costs. d) Unequal-Cost Load Balancing: Used in protocols like EIGRP, where traffic can be split across paths with different metrics, controlled by the variance parameter. e) Load Balancing in Link Aggregation: Combines multiple physical links into a logical link using EtherChannel or LACP. Traffic is balanced using hash-based methods (e.g., source/destination IP or MAC). f) Load Balancing in Application Layer:  Balancers at Layer 7 consider application-specific factors like URL, cookie data, or headers. Examples:  Content-Based Routing: Distributes traffic based on request type.  Session Persistence (Sticky Sessions): Ensures a client remains connected to the same server.