OSI Model Layers and Internet Protocol Stack

1. Advantages of dividing a complex system into layers or modules
2. Taking example of airline system to explain advantage of layering
3. OSI model and Internet Protocol Stack
4. Functions of each layers in OSI model

1. INTERNET PROTOCOL LAYERS

2. How does the communication take place between different devices on internet? End systems(hosts), switch, routers How do we make the internet architecture simple?

3. DESCRIBE AIRLINE SYSTEM

4. ARE YOU ABLE TO CONNECT TO COMPUTER NETWORKS? You are being shipped from source to destination by the airline A packet is shipped from source host to destination host in the Internet. We have still not been able to find a structure.

5. LAYERING OF AIRLINE FUNCTIONALITY

6. CANY YOU THINK OF ANY OTHER SUCH ANOLOGY?

7. ADVANTAGE OF LAYERED ARCHITECTURE Each layer provides a service by Performing some actions within that layer Using the services of layer directly below it Gate layer in the airline architecture Modularity – break complex system into well defined modules Changing implementation of a layer becomes easy Gate layer onboards and deboards people according to their height

8. INTERNET PROTOCOLS A protocol defines the format and the order of messages exchanged between two or more communicating entities, as well as the actions taken on the transmission and/or receipt of a message or other event.

9. TCP/IP PROTOCOL STACK VS OSI MODEL

10. OSI MODEL Proposed in 1970s Protocols were still being developed The inventors of the original OSI model probably did not have the Internet in mind when creating it But some books and training courses picked up OSI model Are the services provided by additional two layers unimportant?

11. REMEMBER THE END GOAL IN NETWORKING

12. Application Layer Contains protocols used by network applications HTTP, SMTP, FTP Network functions: DNS, PING, TELNET, DHCP Distributed on end systems(hosts) Takes help of transport layer to transfer this data Protocol Data Unit(PDU) – message(request and response)

13. TRANSPORT LAYER Transfers application layer messages between hosts TCP and UDP TCP – reliable transfer of messages Each networking application runs on a port Header: Source port and destination port PDU - Segment Takes help of the the network layer to transfer segment packet

14. NETWORK LAYER Transport layer passes the segment packet and a destination address to the network layer Network layer helps in delivering the segment to transport layer in the destination host. Unreliable IP protocol Source and destination IP address Routing protocols PDU – Datagrams Asks data link layer to transfer datagram from one host or router to another

15. Data Link Layer Moves a datagram from one node(host or router) to the next node on the route. Ethernet, WiFi and PPP A datagram may be handled by different link-layer protocols at different links in the route Source and destination MAC address PDU – Frames Data link layer asks the physical layer to transfer the frames from one node to another

16. PHYSICAL LAYER Move individual bits within the frames from one node to next node Different protocols for different mediums like twisted-pair copper wire, fiber, coaxial cable etc.

17. QUESTIONS? Are these layers implemented in software, hardware or a combination of both? Does these layers reside on my laptop or router or the server? Where are all these layers/protocol implemented? How does communication takes place using these protocols?