Ip address concepts

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-- 1 Sub Topic : IP Addressing Concepts Teaching Aids : Diagrams, Animations

Transcript of Ip address concepts

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Sub Topic : IP Addressing Concepts

Teaching Aids : Diagrams, Animations

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Recap

In the previous class, you have learnt about

• Leased line, DSL and Cable MODEM

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Objectives

On completion of this period, you will be able to know about

• What is an IP Address?

• What is network prefix and host number?

• What is Internet address?

• What is sub-netting and no sub-netting?

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What is an IP Address?

• Internet identifier including information about how to reach a network location (via the Internet routing system)

• IPv4: 32-bit number. Written in Dotted Decimal Notation 205.150.58.7.– 4 billion different host addresses

• IPv6: 128-bit number. Written in Hex Decimal Notation2001:0503:0C27:0000:0000:0000:0000:0000

– 16 billion network addresses

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IP Addresses

Application dataTCP HeaderEthernet Header Ethernet Trailer

Ethernet frame

IP Header

version(4 bits)

headerlength

Type of Service/TOS(8 bits)

Total Length (in bytes)(16 bits)

Identification (16 bits)flags

(3 bits)Fragment Offset (13 bits)

Source IP address (32 bits)

Destination IP address (32 bits)

TTL Time-to-Live(8 bits)

Protocol(8 bits)

Header Checksum (16 bits)

32 bits

Fig .1

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Network Prefix and Host Number

•The network prefix identifies a network and the host number identifies a specific host (actually, interface on the network)

•How do we know how long the network prefix is?

–Before 1993: The network prefix is implicitly defined (see class-based addressing)

–After 1993: The network prefix is indicated by a net mask

network prefixnetwork prefix host numberhost number

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• IP addresses are written in a so-called dotted

decimal notation• Each byte is identified by a decimal number in the

range [0..255]:10000000 10001111 10001001 10010000

Dotted Decimal Notation

1st Byte

= 128

3rd Byte

= 137

4th Byte

= 144

128.143.137.144

2nd Byte

= 143

Fig.2

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IP Address

• Every interface have a unique Internet address (IP address)

• Consist of 2 parts – network id and host id

• 32-bit address

• 5 Classes

–A – 0.0.0.0 to 127.255.255.255 (224 nodes)

–B – 128.0.0.0 to 191.255.255.255 (216 nodes)

–C – 192.0.0.0 to 223.255.255.255 (28 nodes)

–D – 224.0.0.0 to 239.255.255.255

–E – 240.0.0.0 to 247.255.255.255

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IP Address contd….

• When Internet addresses were standardized (early 1980s), the Internet address space was divided up into classes• Class A: Network prefix is 8 bits long• Class B: Network prefix is 16 bits long• Class C: Network prefix is 24 bits long

• Each IP address contained a key which identifies the class• Class A: IP address starts with “0”• Class B: IP address starts with “10”• Class C: IP address starts with “110”

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IP address contd…

Class C network id host11 0

Network Prefix24 bits

Host Number8 bits

bit # 0 1 23 242 313

Class B 1 network id host

bit # 0 1 15 162

Network Prefix16 bits

Host Number16 bits

031

Class A 0Network Prefix

8 bits

bit # 0 1 7 8

Host Number24 bits

31

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IP Address contd…

Class D multicast group id11 1bit # 0 1 2 313

04

Class E (reserved for future use)11 1bit # 0 1 2 313

14

05

Fig .4

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Special IP Address

•All 0’s is reserved to refer to a network number

•All 1’s is reserved to refer to a broadcast address

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Sub-netting

• Class A and B has too many nodes

• Network is divided to sub-network

• Improve network performance

• Indicate by subnet mask

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No Sub-netting

• All hosts think that the other hosts are on the same network

128.143.70.0/16

128.143.137.32/16subnetmask: 255.255.0.0

128.143.71.21/16subnetmask: 255.255.0.0

128.143.137.144/16subnetmask: 255.255.0.0

128.143.71.201/16subnetmask: 255.255.0.0

Fig .5

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128.143.0.0/16

128.143.137.32/24subnetmask: 255.255.255.0

128.143.71.21/24subnetmask: 255.255.255.0

128.143.137.144/24subnetmask: 255.255.255.0

128.143.71.201/24subnetmask: 255.255.255.0

128.143.137.0/24Subnet

128.143.71.0/24Subnet

With Sub-netting

• Hosts with same extended network prefix belong to the same network

Fig .6

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Summary

In this class, you have learnt about

• At the network layer, a global identification system that

uniquely identifies every host and router is necessary for

delivery of packet from host –to-host

• An IP v4 address is 32 bit long and uniquely and

universally define a host or router on the Internet

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Summary contd……

• In classfull adressing,the portion of IP address that

identifies the network is called netid

• In classfull adressing,the portion of IP address that

identifies the host or router on the network is called

the hostid

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Summary contd..

• An IP address defines a device’s connection to a network

• There are five classes in IPv4 addresses

• Classes A, B and C differ in the no. of host allowed per network

• Class D is for multicasting and class E is reserved

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(a) 32

(b) 48

(c) 24

(d) None of the above

Quiz

1. IP version 4 is of ______ bits

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(a) 5

(b) 4

(c) 6

(d) None of the above

Quiz

2. In IP addressing there are ___ classes

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Frequently Asked Questions

1. Discuss the concepts of IP addressing

2. Describe the classes of IP version 4 addressing

3. Write a short note on default gate ways