Network Layer and Protocols

IP address is a numeric identifier used to uniquely identify a node on a network.

Two types of IP addresses:

IPv4: 32 bit long, divided into 4 octets
IPv6: 128 bit long, 8 16 bit blocks

Classful addressing range

Class A…..0 to 127
Class B…..128 to 191
Class C……192 to 223
Class D…..224 to 239
Class E…..240 to 255

Special IP addresses

Broadcast: 255.255.255.255
Loopback: 127.0.0.1
Non routable: 0.0.0.0

Subnetting

Subnetting is breaking down large networks into smaller, more efficient subnetworks. One goal of a subnet is to split a large network into a grouping of smaller, interconnected networks to help minimise traffic.
This is done by borrowing some bits from the host part of IP address.

Supernetting

It is exactly opposite of subnetting.
In supernetting smaller networks are combined into a big network

CIDR notation

192.168.0.1/24

Difference between IPv4 and IPv6

IPv4
IPv4 is 32 bit in length, consists of 4 octets
Checksum field is available.
In IPv4, encryption and authentication facility is not available.
Header is of 20-60 bytes in length.

IPv6
IPv6 is 128 bit in length, consists of eight 16 bits blocks
Checksum field is not available.
In IPv6, encryption and authentication facility is available.
Header is of fixed 40 byte length.

VPN

Virtual private network
It is used to protect your identity and your data on the internet.
A VPN encrypts the data before sending it so even if a hacker gets hold of the data it will be meaningless.
Two types of VPN: (1)site-to-site VPN (2) Remote access VPN

Network Layer and protocols