IPv4 AddressingShreehari D. Dhat

2

AgendaWhat is IP address? Why are IP address needed?Types of IP addresses .Classes of IP addresses.NetID and HostID of IP address.IP address range.IP address identification and Netmask.Special IP addresses.IP subnetting.

3

IP Address To have a communication between computers, printers,

scanners etc.To identify each computer uniquely on the network.

4

IP Address continuedIP address is implemented in software.IP addressing mechanism is done at ‘Network’ layer of

OSI model.Two types of IP address are designedIPv4 (32 bit long) and IPv6 (128 bit long)With IPv4 we can have 4294967296 = 232 addresses.With IPv6 we can have 2128 addresses.

5

Format of IP addressIP address is denoted as binary number of 32 bitE.g. 00001010 00001001 01001000 00010111 IP address can also be denoted in human readable format. 00001010 00001001 01001000 00010111 10 . 9 . 72 . 23

6

Classes of IP addressIANA (Internet Assigned Numbers Authority) has defined

standards for classifying the IP address space.IPv4 has an address space 4294967296 = 232

Classes of IP address:-Class A, Class B, Class C, Class D & E

A

B C D E

7

Classes of IP address contd.Classes are identified based on 1st byte of the IP address

(i.e. leading bits also) as follows.Class A :- 00001010 00001001 01001000 00010111Class B :- 10001010 00001001 01001000 00010111Class C :- 11001010 00001001 01001000 00010111

8

Classes of IP address contd.Class D :- 11101010 00001001 01001000 00010111Range of 1st octet for each class Class A :- 0-127 Class B :- 128-191 Class C :- 192-223 Class D :- 224-239 Class E :- 240-255 (reserved)

9

Class A of IP addressClass A occupies largest number of IP addresses. 0 127

0.0.0.1 .... 0.10.2.9 …0.255.255.254 10.0.0.1 … 10.22.10.2 … 10.255.255.254 126.0.0.1 … 126.100.10.3… 126.2555.255.254

Contiguous 128 blocks of IP addresses.16777216 IP addresses per block.1st and last IP address of each block is reserved.

10

Class B of IP address 128 191

128.0.0.1 … 128.0.12.3 … 128.0.255.254 162.0.0.1 … 162.0.12.21… …162.0.255.254 191.0.0.1 … 191.0.12.21… 191.0.255.254

64 contiguous block of IP addresses.65536 IP addresses per block.1st and last IP address of each block is reserved.

11

Class C of IP address192 223

192.0.0.1 ….. 192.0.0.23…. 192.0.0.254 210.0.0.1…. …. 210.0.0.255… 223.0.0.1 ….. 223.0.0.254

32 Contiguous blocks of IP address.256 IP addresses per block.1st and last IP address of each block is reserved.

12

Identifying the IP addressBy referring to the IP address’s first octet IP address class

can be identified. e.g. 10.134.12.33 belongs to class A. 198.99.23.2 belongs to class C. 145.23.24.55 belongs to class B.There are some ranges of IP address reserved for private

and public use.Private IP addresses are used at organization level.

13

Private IP addresses

Router INTERN

ET

10.192.2.1 …10.192.2.2….10.192.2.6

10.192.2.7 121.12.13.2

14

Private IP address contd.Ranges of private IP address.Class A :- 10.0.0.0-10.255.255.255Class B :- 172.16.0.0-172.32.255.255Class C :- 192.168.0.0-192.168.255.255

Remaining are used as Public IP addresses.

15

NetID and HostIDEach IP address is interpreted in two parts

Class A:- 1st byte

Class B:- 1st two bytes

Class C:- 1st three bytes

NetID HostID

NetID HostID

NetID HostID

NetID HostID

16

Netmask mechanismThe Netmask is used to identify the Network id (Net ID)

of the network.Each class has default netmask.Class A:- 255.0.0.0Class B:- 255.255.0.0Class C:- 255.255.255.0How to identify the NetID ?

17

Netmask mechanism contd.To identify the Net ID from IP address e.g. Class A IP address 12.12.3.4 Netmask :- 255.0.0.0& IP address:- 12.12.3.4 i.e.1111 1111 . 0000 0000 . 0000 0000 . 0000 0000&0000 1100 . 0000 1100 . 0000 0011 . 0000 0100

==============================0000 1100 . 0000 0000 . 0000 0000 . 0000 0000 => 12.0.0.0 is Net ID

18

IP SubnettingLets take an example of Class A private IP addressIP address range is 10.0.0.0 – 10.255.255.255So 16777216 IP addresses can be used.All of these IP addresses are assigned to

devices/computers.So the network diagram will look like…

19

IP Subnetting contd.10.0.0.0 Network->

Router

20

IP Subnetting contd.With this network diagram the problem is when there is

broadcast coming from outside network to this network the router will send that broadcast over the network to all hosts.

This will cause network congestion on the network.So to overcome this subnetting is implemented to divide

the broadcast domain.

21

IP Subnetting contd.Subnetting is done by borrowing some number of bits

from host id part of IP address.Class A example 10.0.0.0-255.0.0.0 0000 1010 . 0000 0000 . 0000 0000 . 0000 0000 Net ID Host IDLets borrow 2 bits from host id0000 1010 . 00 00 0000 . 0000 0000 . 0000 0000 Sub Net ID Host ID

NetID HostID

22

IP Subnetting contd.So with two bits borrowed from hostid we can have 4

subnets0000 1010 . 00 00 0000 . 0000 0000 . 0000 0000 = 10.0.0.0 Subnet #1

0000 1010 . 01 00 0000 . 0000 0000 . 0000 0000 = 10.64.0.0 Subnet #2

0000 1010 . 10 00 0000 . 0000 0000 . 0000 0000 = 10.128.0.0 Subnet #3

0000 1010 . 11 00 0000 . 0000 0000 . 0000 0000 = 10.192.0.0 Subnet #4Sunet Mask would be1111 1111 . 11 00 0000 . 0000 0000 . 0000 0000 = 255.192.0.0

23

IP Subnetting contd.So the 4 sub networks would be designed as

Edge Router

10.192.0.0

10.64.0.0

10.0.0.0

10.128.0.0

24

Referenceshttp://www.subnet-calculator.com/Computer Networks by Forouzan.