Networking Basics

• Refer Here

subnets

• sub-network: network can be divided into multiple smaller networks. This smaller network is called as subnet.
• CIDR perspective of subnet
  • Network id of subnet (bytes) will be >= network id of network
  • Examples

Network cidr        Subnet cidr      valid
192.168.0.0/16      192.168.0.0/16    true
192.168.0.0/16      192.168.0.0/24    true
192.168.0.0/16      192.0.0.0/8       false

Exercise: Design a network with subnets for the following case

• For the office we have granted the network with cidr range => 10.10.0.0/16
• This office requires 4 labs with size approx 250 each
• Each lab requries 250 ~> 256 => x.x.x.0/24
• Network => 10.10.0.0/16

Lab1 => 10.10.0.0/24  => 10.10.0.x
Lab2 => 10.10.1.0/24  => 10.10.1.x
Lab3 => 10.10.2.0/24
Lab4 => 10.10.3.0/24

• Now add one more lab of size 512

Router

• Inside Router we have Route tables
• In this route tables we write rules for forwarding packets
• Route tables can understand/restrict based on network ids

# Allow connection b/w lab1 and lab2

Source              Destination
10.10.0.0/24        10.10.1.0/24  => route
10.10.1.0/24        10.10.0.0/24  => route
10.10.0.0/16        0.0.0.0/0     =>  modem

NAT

• Network Address Tranaslator
• It is required to give internet connection to private networks.