In AWS the networks which we will be creating are virtual.
From 5000 feet overview how would aws network which we create look like
In AWS we create network at the region level which we call as vpc (Virtual Private Cloud), But we know that infrastructure in AWS is in Availability zones (AZ’s).
So we create subnets at AZ level. This is where we add resources like virtual machines, databases etc to our network
Basics
Networking principles:
A device on a network can send messages to any other device on the same network
IP Address:
It is a numeric label assigned to each device connected to a computer network.
IP address helps in host and network identification.
IP address is combination of network id and host id
Two devices on the same network will have same network id and different host ids
IP address has two versions
IPv4:
defines IP address as 32 bit number
Eg: 192.168.10.11
Can serve for 2^32 addresses (We cannot use all the ip addresss as there are some reservations)
IPv6:
defines IP address as 128 bit number
Eg: 2001:da8:0:1234:0:678:9:1
Can serve for 2^128 addresses
IPV4 addresses:
An IPv4 address is represented as x.x.x.x each x represent 8 bits or a byte
each position can have a range of 0-(2^8-1) i.e 0-255 so ipv4 range would 0.0.0.0 to 255.255.255.255
In the above image along with ipaddress we also have subnet mask and Default gateway, so are they required
IP address is combination of network id + host id, to determine what is network id and what is host id we need subnet mask.
1 2 3 4
ip address: 192.168.0.106
subnetmask: 255.255.255.0
What are positions where we see 255 => 1,2,3
network id => 192.168.0.0
host id => 106
size of network => what is size of host id => 1 byte => 8 bits
=> 2^n -2 => 2^8-2 => 254
ip address => 10.12.0.5
subnet mask => 255.255.0.0
network id => 10.12.0.0
host id => 0.5
size of network => 2 bytes => 16 bits => 2^16-2 => 65536 - 2 => 65534
Now if you are asked to create a network with capacity of 500 devices, how will i decide on subnet mask. To help in creating networks a classful addressing defintion can be used Refer Here
If we follow this we have 3 subnet masks
Class A => 255.0.0.0 => 2^24 ~= 16,777,216
Class B => 255.255.0.0 => 2^16 ~= 65536
Class C => 255.255.255.0 => 2^8 = 256
For 500 devices if i follow classful network i have to use Class B. Do you think it is a good idea to create class B (65000) for 500 devices
To resolve this CIDR (Classless interdomain routing) was introduced
How CIDR tries to solve the problem
In classful addressing subnet masks are consider as decimal number, what cidr tries is look at subnet mask as a binary number,
ip address: 192.168.0.106
subnet mask: 11111111.11111111.11111111.00000000
255.255.255.0
How many consecutive 1's you have from starting?
24
What is left for hosts => 32-24 => 8 or count zeros =>8
size of network 2^8-2 = 254
In cidr this ip address is written as 192.168.0.106/24
ip address: 192.168.0.106
subnet mask: 11111111.11111111.11111110.00000000
255.255.254.0
How many consecutive 1's you have from starting?
23
What is left for hosts => 32-23=> 9 or count zeros =>9
size of network => 2^9-2 = 510
cidr notation => 192.168.0.106/23
