Proxies & Load Balancing

Master traffic management and distribution patterns for scalable and resilient systems

30 min read•

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Load Balancer Configuration Calculator

Proxy Type

Number of Backend Servers3 servers

Requests per Second1000 RPS

Server Capacity (RPS)500 RPS per server

Load Balancing Algorithm

Health Check Interval (seconds)30 seconds

Enable Session Stickiness

Enable Caching

Load Distribution

Total Capacity:1500 RPS

Utilization:70.18%

Requests per Server:333 RPS

Algorithm Efficiency:95%

Reliability Metrics

Survivable Failures:1 servers

Availability Score:100%

Failure Detection:30s

Recovery Time:60s

Performance Features

Cache Hit Rate:70%

Response Time Reduction:60%

Bandwidth Saving:56%

SSL Termination:Yes

Session Management

Session Complexity:Low

Scalability Impact:Optimal

Proxies and Load Balancing Fundamentals

Proxies and load balancers are essential infrastructure components that manage and distribute network traffic, providing scalability, reliability, and performance optimization for distributed systems.

Proxies

Intermediary servers that forward requests between clients and servers, providing caching, security, and traffic management.

Load Balancers

Distribute incoming requests across multiple backend servers to optimize resource utilization and ensure high availability.

Proxy Server Types

Forward Proxy

Acts on behalf of clients, sitting between users and the internet. Commonly used for content filtering, caching, and anonymity.

✓ Use Cases:

Corporate internet filtering
Anonymous web browsing
Bandwidth management
Content caching

Traffic Flow

Client

→

Forward Proxy

→

Internet

Server sees proxy IP, not client IP

Reverse Proxy

Acts on behalf of servers, sitting in front of backend services. Provides load balancing, SSL termination, and caching.

✓ Use Cases:

Load balancing
SSL termination
Web acceleration
API gateway functionality

Traffic Flow

Client

→

Reverse Proxy

→

Backend

Client sees proxy, not backend servers

Transparent Proxy

Intercepts traffic without client configuration. Often deployed at network gateways for monitoring and filtering.

⚠ Characteristics:

No client configuration needed
Network-level interception
Often used for content filtering
Can impact performance

# iptables rule example

iptables -t nat -A OUTPUT \\

-p tcp --dport 80 \\

-j REDIRECT --to-port 8080

# Intercepts HTTP traffic

Load Balancing Algorithms

Round Robin

Distributes requests sequentially across servers. Simple but assumes equal server capacity.

Request 1 → Server A

Request 2 → Server B

Request 3 → Server C

Request 4 → Server A

# Cycles through servers

Least Connections

Routes new requests to the server with the fewest active connections.

Server A: 5 connections

Server B: 3 connections ← chosen

Server C: 7 connections

Weighted Round Robin

Assigns weights to servers based on their capacity or performance.

Server A (weight: 3): 60% of traffic

Server B (weight: 2): 40% of traffic

Higher weight = more requests

IP Hash

Uses client IP hash to determine server assignment, ensuring session affinity.

hash(192.168.1.100) % 3 = 1

→ Always routes to Server B

# Consistent assignment

Advanced Algorithms

⚡

Least Response Time

Routes to server with fastest response

🎯

Resource Based

Considers CPU, memory usage

🌍

Geographic

Routes based on client location

Health Checks and Failover

Health Check Types

Active Health Checks

Load balancer actively probes servers to verify their health.

# HTTP health check

GET /health HTTP/1.1

Host: backend-server

# Expected: 200 OK

Passive Health Checks

Monitors actual traffic to detect server issues.

5xx errors indicate problems

Timeouts suggest overload

Response time monitoring

Failover Strategies

Immediate Failover

Instantly remove failed servers from rotation. Fast but may cause connection drops.

Graceful Degradation

Gradually reduce traffic to failing servers while monitoring recovery.

Circuit Breaker

Temporarily stop sending traffic, then periodically test for recovery.

Health Check Configuration

# NGINX health check configuration

upstream backend {

server 192.168.1.10:8080 max_fails=3 fail_timeout=30s;

server 192.168.1.11:8080 max_fails=3 fail_timeout=30s;

server 192.168.1.12:8080 max_fails=3 fail_timeout=30s;

}

location /health {

access_log off;

return 200 "healthy\\n";

}

Real-World Implementations

NGINX

• High-performance reverse proxy

• HTTP/2 and SSL termination

• Advanced caching capabilities

• 50M+ websites worldwide

HAProxy

• TCP and HTTP load balancing

• Advanced health checking

• High availability features

• Used by GitHub, Reddit

AWS Application Load Balancer

• Layer 7 load balancing

• Content-based routing

• Auto scaling integration

• Managed service

Cloudflare

• Global CDN and reverse proxy

• DDoS protection

• Edge computing capabilities

• 28M+ internet properties

Envoy Proxy

• Service mesh proxy

• Advanced observability

• gRPC and HTTP/2 support

• Used by Uber, Netflix

F5 BIG-IP

• Enterprise load balancer

• Application delivery controller

• Advanced security features

• High-performance hardware

Implementation Best Practices

🎯 Design for Resilience

• Implement multiple availability zones
• Configure appropriate health checks
• Plan for graceful degradation
• Design circuit breaker patterns

📊 Monitor and Observe

• Track response times and error rates
• Monitor backend server health
• Set up alerting for failures
• Analyze traffic patterns

⚡ Optimize Performance

• Enable caching where appropriate
• Use connection pooling
• Implement SSL termination
• Configure compression

🛡️ Security Considerations

• Hide backend server details
• Implement rate limiting
• Use Web Application Firewall
• Enable DDoS protection

🔧 Operational Excellence

• Automate configuration management
• Implement blue-green deployments
• Plan for capacity scaling
• Document runbooks clearly

📈 Scalability Planning

• Design for horizontal scaling
• Implement auto-scaling policies
• Plan for traffic spikes
• Consider geographic distribution