IP-Internet Protocol Address

Internet Addressing:

Physical-MAC

Logical-IP

Physical/MAC

A media access control address (MAC address) of a device is a unique identifier assigned to a network interface controller (NIC) for communications at the data link layer of a network segment.

MAC addresses are 6-byte (48-bits) in length.

eg. 00-14-22-01-23-45.

IP Address

Numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing.

1. Versions of IP Address

Internet Protocol Version 4 (IPv4)

• 32 bit number
• 4 octets
• Limitation : 4294967296 (2³²) addresses.
• e.g. 172.115.56.48

Internet Protocol Version 6 (IPv6)

• 128 bit number
• 16 octets
• Limitation : (2¹²⁸) 3.403×10³⁸ addresses
• It was developed in 1995 and standardized as rfc2460 in 1998.
• Not yet widely used.
• e.g. 2001:0:9d38:90d7:2c0f:19de:4b28:afba

2. Classes of IP Addresses

IPv4 Classes:

Class	A	B	C	D	E
1st Octet Range	1-126*	128-191	192-223	224-239	240-254
IP Addresses Range	1.0.0.1 to 126.255.255.254	128.1.0.1 to 191.255.255.254	192.0.1.1 to 223.255.254.254	224.0.0.0 to 239.255.255.255	240.0.0.0 to 254.255.255.254
Default Subnet Mask	255.0.0.0	255.255.0.0	255.255.255.0	NA	NA
Network / Host ID	N.H.H.H	N.N.H.H	N.N.N.H	NA	NA
Number of Networks configurable	126 (27 – 2)	16,382 (214 – 2)	2,097,150 (221 – 2)	NA	NA
Number of devices configurable per network	16,777,214 (224 – 2)	65,534 (216 – 2)	254 (28 – 2)	NA	NA
Purpose	Large networks	Medium sized networks	Small networks	Reserved for multi casting	For research and development

• Class A - range 127.0.0.1 to 127.255.255.255 - reserved for loop back and diagnostic purposes.
• Any server / system localhost ip address is 127.0.0.1

3. Types of IP Addresses

Public vs Private IP Addresses

Public IP address is assigned to a computer by the ISP when it is connected to the Internet.

Private IP addresses are used to configure the devices in a private network (LAN / MAN / WAN). 

Static vs Dynamic IP Addresses

Static

• ​Static IP address does not change once it is assigned to a device / computer in a network.
• Since, the IP is static and known there is more possibility for network attacks
• Used by Web Servers, E-mail Servers
• Number of allocatable IP addresses is limited in IPv4.Hence, nowadays it is not possible to connect all the devices that exists in world to Internet simultaneously by using IPv4. 

​​Dynamic

• Dynamic IP addresses are assigned by ISP using DHCP
• ​Available IP address is assigned to a device when it is connected to the network, after the session expiry the IP address released for other device's use.
• Effective use of IP addresses is an advantage of Dynamic IP address assigning.
• Since, the IP address changes frequently, it become not traceable. 

What is Subnetting:

A subnetwork or subnet is a logical subdivision of an IP network. The practice of dividing a network into two or more networks is called subnetting. Computers that belong to a subnet are addressed with an identical most-significant bit-group in their IP addresses

Why Sub netting Required ?

Subnetwork, or subnet, is a logically subdivision of

an IP network.

Method to divide network into two or more

networks.

Shortage of IP Address

Classless IP- No Network IP no Host ID.

Easy to manage smaller network then bigger

network.