MultiCloud Classroom notes 22/Jun/2025

Networking contd

Examples

• Create private network 4 subnets with 50000 devices

size = 200000
2^n ~= 200000
n = 18
N = 14

ip: 172.16.0.0/14
nsm: 11111111.11111100.00000000.00000000

• subnets

size = 50000
2^n ~= 50000
n = 16

nsm:  11111111.11111100.00000000.00000000
ssm:  11111111.11111111.00000000.00000000
ip:        172.000100xx.0.0/16
s1:        172.00010000.0.0/16 = 172.16.0.0/16
s2:        172.00010001.0.0/16 = 172.17.0.0/16
s3:        172.00010010.0.0/16 = 172.18.0.0/16
s4:        172.00010011.0.0/16 = 172.19.0.0/16

AWS

• In AWS all basic networking activities are handle by a service called as VPC (Virtual Private Cloud)
• At its very core vpc can create a network
• Core components of vpc

• Internet Gateway: This provides dual internet access
• Egress Gateway: This provides internet access to vpc (similar to home connections)
• Subnet: This is subnetwork where resources are connected to the network
• Route table: simulates the router
• Security Group: kind of a firewall for server
• Network ACL: kind of firewall for subnet
• NAT Gateway: when you want to provide internet for private subnets
• When we create a vpc, AWS creates
  • a route table which is associated to all subnets and enables all internal communication.
  • A default security group and default NACL are created.
• Also aws creates one default vpc in every network.

Lets create a vpc with 4 subnets

• Steps
  
  
  
  
  
  

Principle

• Two networks cannot be connected if they have common ip addresses
• Example
  • Network A has cidr range of 192.168.0.0/24 and network 2 has cidr range 192.168.0.0/16
    • network a = 192.168.0.0 to 192.168.0.255
    • netowrk b = 192.168.0.0 to 192.168.255.255
  • Network A has cidr range of 10.100.100.0/24 and network B has cidr range of 10.100.101.0/24 can they communicate
  • network A = 10.100.100.0 to 10.100.100.255
  • network B = 10.100.101.0 to 10.100.101.255

Exercise:

• Explore this website