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The Network Layer in the Internet

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Internet Protocol [IP]

Is a host-to host network layer delivery protocol.

It is unreliable & Connectionless Datagram Protocol.

It is a best effort delivery service.

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IP HEADER

32 bits

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Type of Service

D- Delay T- Throughput R- Relay

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Control Flags

Bit 0: reserved, must be zero

Bit 1: (DF) 0 = May Fragment, 1 = Don't Fragment.

Bit 2: (MF) 0 = Last Fragment, 1 = More Fragments.

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Protocol

Defines the higher level protocols that uses the services of IP layer.

Header

ICMP IGMP OSPF

TCP UDP

Network Layer

Transport Layer

Value Protocol

1 ICMP

2 IGMP

6 TCP

17 UDP

89 OSPF

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Options

Option Description

Security Specifies how secret the datagram

Strict source routing Gives the complete path to be followed

Loose source routing Gives a list of routers not be missed.

Record route Makes each router append its IP address

Timestamp Makes each router append its IP address and Timestamp

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IP Address

Common Notation to show a n IP address 1. Binary Notation. [BN] 2. Dotted Decimal Notation. [DDN]

Eg:

10000000 00001011 00000011 00011111

128.11.3.31

BN

DDN

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1.0.0.0 to 127.255.255.255

224.0.0.0 to 239.255.255.255

HostNetwork0

HostNetwork10

HostNetwork110

Multicast Address1110

Reserved for future use11110

Class

A

B

C

D

E

128.0.0.0 to 191.255.255.255

192.0.0.0 to 223.255.255.255

240.0.0.0 to 247.255.255.255

32 bits

Classful Addressing

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Subnet & Subnet Mask

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Internet Control Protocols

ICMP – Internet Control Message Protocol ARP -- Address Resolution Protocol RARP - Reverse Address Resolution

Protocol BOOTP- BOOTstrap Protocol

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ICMPInternet Control Message

ProtocolIP has two deficiencies

1. Lack of Error Control

2. Lack of Assistance Mechanisms

To overcome these deficiencies ICMP was designed.

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ICMP – Types of Messages

ICMP messages can be divided into two broad categories:

1. Error Reporting Messages

2. Query Messages

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Error Reporting

Destination Unreachable

Source Quench

Time Exceeded

Parameter Problems

Redirection

Error Reporting Messages

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Query Messages

Query

Echo request & reply

Time stamp request & reply

Address Mask request & reply

Router solicitation & advertisement

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The Address Resolution Protocol

1 2 3 4

E1 E2 E3 E4 E5 E6 Ethernet Addresses

EE Ethernet

192.31.63.0

Campus FDDI ring

192.31.60.0CS Ethernet

192.31.65.0

192.31.65.7 192.31.65.5 192.31.63.8

To WAN

F1

F2

F3

Router has 2 IP addresses

192.31.60.4

192.31.65.1

Router has 2 IP addresses

192.31.60.7

192.31.63.3

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Reverse Address resolution protocol

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BOOTP Protocol

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Self Study

The Interior Gateway Routing Protocol

[OSPF] The Exterior Gateway Routing Protocol

[BGP] Internet Multicasting Mobile IP Classless InterDomain Routing [ CDIR]