Why LB

• High Availability during Maintenance and unplanned Downtimes
• Service Discovery or Service Entry point
• Scale Horizontally after all its Load Balancing

Basic Load Balancer

• Distribute Traffic based on algo roundrobin, least connections etc

How is HA achieved

ELB handles differently

• L3 vs L4 vs L7 Health Checks

Connection Tracking and Dual TCP connections

• Connection Reuse
• Client IPs by L7 custom header or L4 proxy protocol
• L7 content switching

SSL offload

• SSL performance
• CDN
• SSL Passthrough, sticky session

Skip Dual TCP Pros and Cons

• L2 and L3 DSR- skim
• NLB
• State Tracking
• SSL offloading

https://blog.envoyproxy.io/introduction-to-modern-network-load-balancing-and-proxying-a57f6ff80236