F451 - Internet Protocol

• IP stands for Internet Protocol.
• IP specifies the format of packets, also called datagrams, and the addressing scheme. Most networks combine IP with a higher - level protocol called Transmission Control Protocol (TCP), which establishes a virtual connection between a destination and a source.
• TCP establishes a connection between 2 hosts so that they can send messages back and forth for a period of time (duplex).

Purpose:

• Need a standard means of communication between devices.
• Can't communicate if speaking 2 different languages.
• The IP defines the basic unit of data transfer (IP diagram).
• IP software performs the routing function.
• IP includes a set of rules that process the idea of unreliable packet delivery.

What is protocol? 

• Rules and conventions explaining how something must be done.
• Used to describe how devices can communicate.

Each datagram has 2 components:

• Header 
• Payload

Please - physical

Dear - data link

Never - network

Try - transport

Stealing - session

People's - presentation

Apples - application

IP supports the following following services:

• One-to-one (unicast)
• One-to-all (broadcast)
• One-to-several (multicast)

Physical Layer:

• This layer deals with the Hardware of network.

Data Link Layer:

• This layer deals with MAC addresses of devices.
• Responsible for physical addressing, error correction & preparing the information for the media frames.

Network Layer:

• This layer deals with Packets (data bundles).
• Responsible for logical addressing and routing.

Transport Layer:

• This layer deals with segments.
• Breaks information into segments and is responsible for connection & connectionless communication.
• Hardware: proxy server, gateways, firewall,...

Session Layer:

• Responsible for establishing, managing & terminating user connections.
• Acknowledgements of data received during a sessions.
• Retransmission of data if it is not received by a device.

Presentation Layer:

• Allows hosts & applications to use a common language.
• Performs..
• Data formatting.
• Encryption & Decryption for security.
• Compression & Expansion.

Application Layer:

• This layer is what the user sees. 
• Provides Interface for users to communicate with applications.

IP - Internet protocol.
ARP - Address Resolution Protocol.
ICMP - Internet Control Message Protocol.

IP address:

• An IP address is a unique global address for a network interface.
• Is a 32 bit long  identifier.
• Encodes a network number (network prefix) and a host number.
• In high-order bit is set to 0, the next seven bits complete the network ID, the remaining 24 buts represent the host ID.
• The 2 high order bits in class B are set to 10, the next 14 are used to complete the network ID, the remaining 16 bits represent the host ID.

Subnetting:

• Subnetting enables the network administrator to further divide the host part of the address into 2 or more subnets.
• In this case, a part of the host address is reserved to identify the particular subnet.
• This is easier to see if we show the IP address in binary format.

Journey to IP versions: 

• IPV(1-3) : 
• Were not formally assigned.
• IPV4 : 
• TCP/IP, 32 bit IP address currently used.
• IPV5 : 
• Internet stream protocol (SP).
• IPV6 : 
• Designed to replace IPV4, 128 bit IP address.