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?