Overview of two Model

1. ASSIGNMENT OBJECTIVES
 Discuss the most popular ISO-OSI 7-layer
communication reference model
 Explain the reference model and standards
relevant to network communications
 Explain TCP/IP Model

2. MODELS AND STANDARDS IN
COMMUNICATION
 Communication
 Established standards
 Standards are known as protocols
 Implementation
 A framework is helpful in the design of hardware and
software for communication
 ISO-OSI Model serves this purpose
 ISO-OSI supersedes the TCP/IP model

3. ISO AND OSI DEFINED

4. OSI MODEL BACKGROUND
 Introduced in 1978 and revised in 1984
 Formulates the communication process into
structured layers
 There are seven layers in the model, hence the
name the 7-Layer model
 The model acts as a frame of reference in the
design of communications and networking
products

5. DIVISION OF LAYERS
Upper Layers
Lower Layers
Middle Layer
7. Application
6. Presentation
5. Session
4. Transport
3. Network
2. Data Link
1. Physical

6. 7. APPLICATION LAYER
 Purpose
 User application to network service interface
 Examples
 File request from server
 E-mail services

7. APPLICATION LAYER FUNCTION
 Function
 General network access
 Flow control
 Error recovery

8. 6. PRESENTATION LAYER
 Purpose
 Formats data for exchange between points of
communication
 Example:
 Redirector software
 Formats for transmission to the server

9. PRESENTATION LAYER FUNCTION

10. 5. SESSION LAYER
 Purpose
 Oversee a communication session
 Establish
 Maintain
 Terminate
 Function
 Performs name recognition and related security
 Synchronization between sender and receiver
 Assignment of time for transmission
 Start time
 End time etc.

11. 4. TRANSPORT LAYER
 Purpose
 Repackage proper and efficient delivery of packages
 Error free
 In sequence
 Without duplication

12. TRANSPORT LAYER FUNCTION
 For sending data
 Repackage the message to fit into packets
 Split long messages
 Assemble small messages
 On receiving data
 Perform the reverse
 Send an acknowledgment to the sender
 Solve packet problems
 During transmission and reception

13. 3. NETWORK LAYER
 Purpose
 Addressing and routing the packets
 Example application at the router
 If the packet size is large, splits into small packets

14. NETWORK LAYER FUNCTION
 Address messages
 Address translation from logical to physical
 Ex: nganesa ----------> 102.13.345.25
 Routing of data
 Based on priority
 Best path at the time of transmission

15. 2. DATA LINK LAYER
 Purpose
 Manages the flow of data over the physical media
 Responsible for error-free transmission over the
physical media
 Assures error-free data submission to the
Network Layer

16. DATA LINK LAYER FUNCTION
 Point of origin
 Packages data for transmission over physical line
 Receiving end
 Packages data for submission to the network layer

17. DATA LINK LAYER SUBDIVISION
 Improvement to ISO Model
 Logical Link Control (LLC) sub-layer
 Manages service access points (logical link)
 Error and flow control
 Media Access Control (MAC) sub-layer
 Applies directly to network card communication
 Access control

18. 1. PHYSICAL LAYER
 Purpose
 Deals with the transmission of 0s and 1s over the
physical media
 Translation of bits into signals
 Example
 Pulse duration determination
 Transmission synchronization
 etc.

19. PHYSICAL LAYER FUNCTION
 Encode bits into signals
 Carry data from the higher layers
 Define the interface to the card
 Electrical
 Mechanical
 Functional
 Example: Pin count on the connector

20. TCP/IP REFERENCE MODEL
 There are four layers of the TCP/IP
reference model (DARPA model as named
by the US Government Agency)
 The ISO-OSI reference model is composed of
seven layers
 The next slide shows the mapping of the
ISO/OSI model to the TCP/IP model
 Note that the ISO/OSI model is more
widely used and accepted but the TCP/IP
model is easy to comprehend

21. COMPARISON OF ISO-OSI MODEL
AND THE TCP/IP MODEL
Application
Application
Presentation
Session
Transport Host-to-Host
Network Internet
Data Link
Network Access
Physical

22. TCP/IP LAYERS

23. NETWORK INTERFACE LAYER
 Responsible for sending and receiving TCP/IP
packets on the network medium (physical/Data
Link)
 Applicable LAN technologies
 Ethernet, Token Ring, FDDI etc.
 Applicable WAN technologies
 X.25 (old), Frame Relay, ATM etc.
 Note that some technologies such as ATM and
FDDI may be used at both the WAN and the
LAN levels

24. INTERNET LAYER

25. CORE INTERNET LAYER
PROTOCOLS
 IP
 A connectionless unreliable protocol that is
part of the TCP/IP protocol suite
 ARP (Address Resolution Protocol)
 Resolves IP addresses to MAC addresses
 ICMP (Internet Control Message
Protocol)
 Diagnostics and error reporting
 (IGMP) Internet Group Management
Protocol
 Management of group multicast

26. TRANSPORT LAYER
 Sequencing and transmission of packets
 Acknowledgment of receipts
 Recovery of packets
 Flow control
 In essence, it engages in host-to-host
transportation of data packets and the delivery of
them to the application layer

27. CORE PROTOCOLS OF THE
TRANSPORT LAYER
TCP
(Transmission
Control Protocol)
UDP (User
Datagram Protocol)
Transport Layer

28. APPLICATION LAYER
 Provides applications with the ability to access
the services of the other layers
 New protocols and services are always being
developed in this category

29. SOME CORE PROTOCOLS

30. REFERENCE
MATERIAL
 https://www.techopedia.com
 https://en.wikipedia.org
 https://slideshare.net
ThE ENd