OSI Networking Model

• Refer Here for OSI Networking model
• Refer Here for loadbalancing basics
• Load balancers balance the load across multiple physical/virtual machines
• Loadbalancers will be of two types
  • Layer 4 loadbalancer
    • Aware of tcp, udp
    • Aware of ip address and port
    • These loadbalancer can send traffic to different servers on their ip addresses on some networking port
  • Layer 7 loadbalancer
    • Aware of http & https
    • Aware of tcp, udp
    • Aware of ip address and port
    • These loadbalancers since they http aware they can send the traffic to servers depeding on uri

Loadbalancing in Azure

• Azure provides load balancers which support layer 4 and layer 7 loadbalancing. Azure gives the option for a public loadbalancers and also internal loadbalancers
• Azure Loadbalancer:
  • This loadbalancer is Layer 4 loadbalancer
• Azure Application Gateway
  • This is Layer 7 Loadbalancer.

Exercise: Layer 4 Load balancing with static machines

• Lets create two vm with lamp vm image
• Now navigate to home => All Services
• Refer Here for standard vs basic load balancer comparision
• After the lb is created, we must apply configuration in order to use. We have defined the frondend of loadbalancer, so now we need to configure the backend pool
• There should be some way to identify the machine is healthy or not, load balancers use health probes for that.
• We need to add load balancing rules
• Now navigate to loadbalancer overview page and use public ip to buiild http://<publicip>/info.php