OSI & TCP/IP

Model(s)By Muhammad HanifBy Muhammad Hanif

Quotes of the Day

“Seek knowledge from the cradle to the grave.”

Hazrat Muhammad (P.B.U.H)

“When you know better you do better.”Maya Angelou

“Intelligence plus character-that is the goal of true education.”

Martin Luther King Jr.

Open Systems Interconnection (OSI) is a set of internationally recognized standards for networking and for operating system involved in networking functions.

In 1978, the International Standards Organization (ISO) began to develop its OSI framework architecture.

The concept of a 7 layer model was provided by the work of Charles Bachman.

OSI Model

Data unit

Layer Function

Hostlayers

Data

7. ApplicationNetwork process to application

6. PresentationData representation, encryption and decryption

5. Session Inter host communication

Segments

4. TransportEnd-to-end connections and reliability, Flow control

Medialayers

Packet 3. NetworkPath determination and logical addressing

Frame 2. Data Link Physical addressing

Bit 1. PhysicalMedia, signal and binary transmission

Going from layer 1 to 7: Please Do Not Throw Sausage Pizza AwayGoing from layer 7 to 1: All People Seems To Need Data Processing

7 Layers7. Application Layer All

8. Presentation Layer People

9. Session Layer Seems

10. Transport Layer To

11. Network Layer Need

12. Data Link Layer Data

7. Physical Layer Processing

Tasks involved in sending letter

LAYER 7 – The APPLICATION Layer• The top layer of the OSI model

• Provides a set of interfaces for sending and receiving applications to gain access to and use network services, such as: network file transfer, message handling and database query processing

• Protocols are HTTP, Telnet, FTP etc

LAYER 7 – The APPLICATION Layer

• The application layer provides set of Interfaces and is responsible for providing services to the user.

LAYER 6 – The PRESENTATION Layer

• Manages data-format information for networked communications (the network’s translator)

• For outgoing messages, it converts data into a generic format for network transmission.

• For incoming messages, it converts data from the generic network format to a format that the receiving application can understand

• This layer is also responsible for • Certain protocol conversions

• Data encryption/decryption,

• Data compression/decompression

LAYER 6 – The PRESENTATION Layer

• The presentation layer is responsible for translation, compression, and encryption.

LAYER 5 – The SESSION Layer

• Enables two networked resources to hold ongoing communications (called a session) across a network

• Applications on either end of the session are able to exchange data for the duration of the session.

• This layer is responsible for initiating, maintaining and terminating sessions

The session layer is responsible for dialog control and synchronization.

LAYER 5 – The SESSION Layer

LAYER 4 – The TRANSPORT Layer

• Manages the transmission of data across a network

• Manages the flow of data between parties by segmenting long data streams into smaller data chunks called segments. (based on allowed “packet” size for a given transmission medium)

• Reassembles segments into their original sequence at the receiving end

• Provides acknowledgements of successful transmissions and requests resends for packets which arrive with errors

LAYER 4 – The TRANSPORT Layer

• Establishes End-to-End Connectivity• Can ensures reliable delivery

• i.e. error detection and retransmission

• Typical Layer 4 Protocols• Transmission Control Protocol (TCP)• User Datagram Protocol (UDP)

LAYER 4 – The TRANSPORT Layer

• The transport layer is responsible for the delivery of a message from one process to another.

LAYER 3 – The NETWORK Layer• Handles logical network addresses for delivery

• Responsible for deciding how to route transmissions between computers

• This layer also handles the decisions needed to get data from one point to the next point along a network path

• This layer also handles packet switching and network congestion control

LAYER 3 – The NETWORK Layer• Provides connectivity and path selection

• E.g. Routing

• Typical Layer 3 Devices and Protocols

• Routers, IPv4, IPv6

• For logical address go to command Prompt

• Ipconfig/all

LAYER 3 – The NETWORK Layer

• The network layer is responsible for the delivery of individual packets from the source host to the destination host.

LAYER 2 – The DATA LINK Layer• Handles special data frames (packets) between the

Network layer and the Physical layer

• At the sending end this layer handles conversion of data into raw formats that can be handled by the Physical Layer

• At the receiving end, this layer packages raw data from the physical layer into data frames for delivery to the Network layer

LAYER 2 – The DATA LINK Layer• Defines data format for transmission

• E.g. Ethernet, Frame Relay, PPP

• Controls access to Physical media

• Defines Physical Addressing

• E.g. Ethernet MAC address

• Typically has error detection

• E.g. Cyclical Redundancy Check (CRC)

• Typical Layer 2 Devices and Protocols

• Bridges, Switches, Wireless Access Points, Ethernet, PPP

LAYER 2 – The DATA LINK Layer• The data link layer is responsible for

moving frames from one hop (node) to the next.

LAYER 1 – The PHYSICAL Layer

• Converts bits into electronic signals for outgoing messages

• Converts electronic signals into bits for incoming messages

• This layer manages the interface between the computer and the network medium (coax, twisted pair, etc.)

• This layer tells the driver software for the MAU (media attachment unit, e.g. network interface cards (NICs, modems, etc.)) what needs to be sent across the medium

• The bottom layer of the OSI model

LAYER 1 – The PHYSICAL Layer

• Defines physical media properties• Electrical Functions

• Data Rates

• Physical Connectors

• Cable Distances

• Optical Wavelengths

• Wireless Frequencies

• Typical Layer 1 Devices• Twisted pair cable, Fiber Optics Coaxial cable, WiFi, etc

LAYER 1 – The PHYSICAL Layer

The physical layer is responsible for movements of individual bits from one hop (node) to the next.

Remember

A convenient aid for remembering the OSI layer names is to use the first letter of each word in the phrase:

All People Seems To Need Data Processing

OSI Model at a Glance

Introduction TCP/IPIntroduction TCP/IP The Internet Protocol Suite (commonly

known as TCP/IP) is the set of communications protocols used for the Internet and other similar networks.

It is named from two of the most important protocols in it: the Transmission Control Protocol (TCP) andthe Internet Protocol (IP), which were the first

two networking protocols defined in this standard.

OSI V/S TCP/IP LayersOSI V/S TCP/IP Layers

OSI TCP/IP

Application Layer

Application Layer Presentation Layer

Session Layer

 Transport Layer Transport Layer

Network Layer  Internet Layer

Data Link LayerLink Layer 

Physical Layer

TCP/IP StackTCP/IP Stack

TCP/IP Protocol SuiteTCP/IP Protocol Suite

Layer Protocol

Application

DNS, TFTP, TLS/SSL, FTP, HTTP, IMAP, IRC, NNTP, POP3, SIP, SMTP, SMPP, SNMP, SSH, Telnet, Echo, RTP, PNRP, rlogin, ENRP

Transport

TCP, UDP, DCCP, SCTP, IL, RUDP, RSVP

Internet

IP (IPv4, IPv6), ICMP, IGMP, and ICMPv6

Routing protocols like BGP and RIP which run over TCP/UDP, may also be considered part of the Internet Layer.

Link PPP, MAC, ARP, RARP, OSPF (IPv4/IPv6), IS-IS, NDP

Assignment No. 1 + Quiz 1 Write detail note on OSI model.

Deadline:Next Week Same Class

Thanks