1. Higher National Diploma1 Network Concepts OSI 7 Layer model

2. Btec National Diploma Level 32 Aims Discuss what is meant by a Standard Look into the different aspects of OSI and discuss what devices relate to the 7 layers

3. Btec National Diploma Level 33 OSI What is a standard? “A principle commonly agreed to by experts in the conduct and use of evaluation for the measure of the value or quality of an evaluation.” ec.wmich.edu/glossary/prog-glossary.htf

4. Btec National Diploma Level 34 OSI What does OSI stand for? Open Systems Interconnection What is OSI for? Describe network communication between network devices. It is a standard that has been agreed by the ISO – international standards organisation. Any two computers can communicate when connected regardless of underlying architecture

5. Btec National Diploma Level 35 OSI Cont. The OSI model is represented by seven layers. The seventh layer being the top which is nearest the user. One being the bottom for the communication medium (the data leaving the computer).

6. Btec National Diploma Level 36 LayerOSI RoleRelated to a Network 7Application Email and web browsers – many protocols associated to it. 6PresentationOrganisation of data into a format that can be used by humans ASCII - Plain text for web pages Doc – Word documents 5SessionThis allows you to have multiple browsers and resources open simultaneously without data conflicts in transmission. 4TransportFirewalls, layer 4 switches operate at this level; 3NetworkLogical address for a server or workstation is managed here – common protocol is TCP/IP. Routing takes place at this level 2Data LinkPhysical address (Media access control (MAC)) Used to identify the device. Frame relay 1PhysicalCables/wireless encoding of bits of data 0001111010101, Hubs

7. Btec National Diploma Level 37 Application Layer 7 The application layer is the OSI layer closest to the end user, which means that both the OSI application layer and the user interact directly with the software application. This layer interacts with software applications that implement a communicating component. Examples? Web browser, Email

8. Btec National Diploma Level 38 Presentation Layer 6 Presents data to the user in understandable format Provides conversion functions for application layer data. Examples? Data representation – graphic formats Character representation – text / ASCII

9. Btec National Diploma Level 39 Session Layer 5 Manages connections between machines Determines whether all data transmitted / received It provides for full-duplex, half-duplex, or simplex operation. Enables the use of multiple browser, chat and email to be opened simultaneously.

10. Btec National Diploma Level 310 Transport Layer 4 The Transport Layer provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers. Examples? Firewalls VOIP

11. Btec National Diploma Level 311 Network Layer 3 Routing and addressing functions – correct destinations Receives incoming packets of data Routing – decides what route to use Forwarding – sends on packets to other hosts

12. Btec National Diploma Level 312 Data Link Layer 2 Organisation of data bits into frame structure The beginning and end of the data frame The address of the sender The address of the receiver Error checking of the data frame

13. Btec National Diploma Level 313 Physical Layer 1 Transmits / receives data bits as electrical pulses Controls physical link between communicating systems Describes network topology Transmission media – cabling / broadcasting Transmission devices – NICs / modems Electrical or optical (fibre optic) signalling

14. Btec National Diploma Level 314 Conclusion Discussed what is meant by a Standard Look into the different aspects of OSI and discussed what devices relate to the 7 layers