This tutorial help you to learn about Computer Network. Key Concepts: Protocol Layers, Advantages of Layering. Protocols, Open System Protocols, Network Protocols, Internet Protocol Stack, Postal Network, Protocol Layering & Data For more detail visit Tech Blog: https://msatechnosoft.in/blog/

1. In this video we are going to discuss
• Protocol Layers
• Advantages of Layering
• Protocols
• Open System Protocols
• Network Protocols
• Internet Protocol Stack
• Postal Network
• Protocol Layering & Data

2. Protocol Layers
• The idea: a series of steps
• A way for organizing structure of network

3. Advantages of Layering
explicit structure allows identification & relationship of complex
system’s pieces
layered reference model for discussion
modularization eases maintenance & updating of system
change of implementation of layer’s service transparent to rest of system

4. Protocols
 A protocol is a set of rules and formats that govern the communication
between communicating peers
 set of valid messages
 meaning of each message
 Necessary for any function that requires cooperation between peers

5. Protocols
A protocol provides a service
For example: the post office protocol for reliable parcel transfer service
Peer entities use a protocol to provide a service to a higher-level
peer entity
for example, truck drivers use a protocol to present post offices with the
abstraction of an unreliable parcel transfer service

6. Protocol Layers
A network that provides many services needs many protocols
Some services are independent, But others depend on each other
A Protocol may use another protocol as a step in its execution
for example, ground transfer is one step in the execution of the example
reliable parcel transfer protocol
This form of dependency is called layering
Post office handling is layered above parcel ground transfer protocol.

7. Open Systems
Proprietary system A system that uses technologies kept private by a
particular commercial vendor
 One system couldn’t communicate with another, leading to the need for
Interoperability The ability of software and hardware on multiple
machines and from multiple commercial vendors to communicate
 Leading to
Open systems System based on a common model of network
architecture and a suite of protocols used in its implementation

8. Open Systems
The International
Organization for
Standardization (ISO)
established the Open
Systems Interconnection
(OSI) Reference Model
Each layer deals with a
particular aspect of
network communication
Figure : The layers of the OSI Reference Model

9. Network Protocols
Network protocols are layered such that each one relies on the
protocols that underlie it
Sometimes referred to as a protocol stack
Figure : Layering of key network protocols

10. Open protocols and systems
A set of protocols is open if
protocol details are publicly available
changes are managed by an organization whose membership and
transactions are open to the public
A system that implements open protocols is called an open system
International Organization for Standards (ISO) prescribes a
standard to connect open systems
open system interconnect (OSI)
Has greatly influenced thinking on protocol stacks

11. Postal network
Application: people using the postal system
Session and presentation: chief clerk sends some priority mail, and some by
regular mail ; translator translates letters going abroad.
mail clerk sends a message, retransmits if not acked
postal system computes a route and forwards the letters
datalink layer: letters carried by planes, trains, automobiles
physical layer: the letter itself

12. Internet protocol stack
 application: supporting network applications
 ftp, smtp, http
 transport: host-host data transfer
 tcp, udp
 network: routing of datagrams from source to destination
 ip, routing protocols
 link: data transfer between neighboring network elements
 ppp, ethernet
 physical: bits “on the wire”
application
transport
network
link
physical

13. application
transport
network
Link
physical
application
transport
network
Link
physical
source destination
M
M
M
M
Ht
HtHn
HtHnHl
M
M
M
M
Ht
HtHn
HtHnHl
message
segment
datagram
frame
Protocol layering and data