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 : (21283.403×1038 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.



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