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LoadBalancers

Updated Jan 16, 2019 ·

Overview​

Load Balancers prevent overloading of any single resource by distributing the incoming network traffic traffic across multiple servers.

  • Provide high availability by redirecting traffic during server failures.
  • Balance loads based on various algorithms, such as round-robin or least connections.
  • Improve response times and optimize resource usage.

Concepts​

  • Session Persistence

    • User sessions are consistently directed to the same server in a load-balanced environment.
    • Useful for applications where user session state must be maintained across multiple requests.
    • Often implemented through cookies or session IDs that are recognized by the load balancer.

  • Round-robin

    • Incoming requests are distributed sequentially to each server in a set.
    • No server-specific criteria are considered; each server gets an equal share of traffic.
    • Effective for evenly distributed, stateless applications.

  • Least Connections

    • Directs traffic to the server with the fewest active connections.
    • BalanceS load more effectively, where some servers may be faster or more capable.
    • Can be more efficient in handling sessions that require significant processing power.

  • Weighted Value

    • Uses predefined weights assigned to each server based on capacity or performance.
    • Higher weights meant servers can handle more traffic or have better performance capabilities.
    • Allows for more fine-tuned control over how traffic is distributed across servers.

Security Functions​

  • SSL Certificate Management

    • Handles the encryption of data exchanged between servers and clients
    • Manages certificate issuance, renewal, and revocation
    • Ensures secure data transmission by encrypting and decrypting traffic

  • URL Filtering

    • Controls access to specific web resources based on URL patterns
    • Blocks or allows traffic based on predefined URL rules
    • Helps prevent access to malicious or inappropriate websites

  • Other Web Application Security Tasks

    • Protection against web-based attacks such as SQL injection and cross-site scripting (XSS)
    • Monitors and analyzes traffic for suspicious behavior
    • Implements application firewalls to block unauthorized access

Application Delivery Controllers​

Application Delivery Controllers (ADCs) are network devices that enhance the performance and reliability of applications delivered over the internet or intranet.

  • Advanced form of a load balancer; can optimize application delivery
  • Load balancing, SSL termination, content caching, and HTTP compression
  • Integrated firewall and DDoS protection