Functions and Devices of Physical layer of ISO-OSI model. Functions of all the layers in brief and simple ways to remember all in order.

1. Computer Networks
ISO – OSI Physical Layer Devices
Presentation By : Md. Shahid Khan
Headed By : Jani Sir

2. ISO-OSI Model
InternationalStandardsOrganization-OpenSystemsInterconnection
 The concept of a seven-layer model was provided by the
work of Charles Bachman, Honeywell Information
Services.
 OSI is not a protocol but a model for understanding and
designing a network architecture that is flexible and
robust.
 “Open” means the concepts are non propriety , can be
used by anyone.

3. Layered Approach
APPLICATION
PRESENTATION
SESSION
TRANSPORT
NETWORK
DATA LINK
PHYSICAL
Please
Do
Not
Tell
Secrets
Passwords
Anytime
All
People
Seem
To
Need
Data
Processing

4. Functions Of Layers
To allow access to network resources.
To translate , encrypt and compress data.
To establish , manage and terminate sessions.
To provide reliable end-to-end message
delivery.
To move packets from source to destination.
To organize bits into frames.
To transmit bits over a medium and provide
electrical specs.

5. Physical Layer (PHY)
The physical layer consists of the basic networking
hardware transmission technologies of a network.
It is a fundamental layer underlying the logical data
structures of the higher level functions in a network.
Due to the plethora of available hardware technologies
with widely varying characteristics, this is perhaps the
most complex layer in the OSI architecture.

6. Functions of Physical Layer
Bit Representation
Transmission Rate
Physical Characteristics
Synchronize
Transmission mode
Physical Topology

7. Physical Layer Devices
Cables
Connectors
Repeaters
Passive Hub
Simple Active Hub
Transmitters
Multiplexers
Receivers
Transceivers
Couplers

8. Cables
•802.3 cabling
10 Base 5
10 Base 2
10 Base -T
10 Base -F

9. Connectors
UTP Connector
• RJ45
Coaxial Cable Connector
• BNC
• BNC-T
• BNC Terminator
Fiber Optic Cable Connector
• SC Connector
• ST Connector
• MT-RJ

10. Standard RJ45
• Ethernet physical layer device.
• A standard 8P8C (often called RJ45) connector used most commonly
on cat5 cable, one of the types of cabling used in Ethernet networks
• Standard IEEE 802.3 (2002 onwards)
• Physical media Coaxial cable, twisted pair, optical fiber
• Network topology Point-to-point, star, bus
• Major variants 10BASE-T, 10BASE2,100BASE-TX ,100BASE-T
• Maximum distance 100 metres over twisted pair, up to 100 km
over optical fibre.
• The Ethernet physical layer is the physical layer component of the
Ethernet family of computer network standards.

11. InterconnectingLANs
Q: Why not just one big LAN?
Limited amount of supportable traffic: on single LAN, all
stations must share bandwidth
limited length: 802.3 (Ethernet) specifies maximum cable
length
large “collision domain” (can collide with many stations)
limited number of stations: 802.5 (token ring) have token
passing delays at each station

12. Repeaters
 Why to need - Attenuation : Length of cable
used influence the quality of
communication.
 Repeaters repeat signals
– Clean and boost digital transmission.
 Repeaters only work with the physical
signal
– Cannot reformat, resize, or manipulate the data.

13. Regeneratestheoriginalbitpattern
Creates exact duplicate of incoming data by identifying it amidst the noise.

14. RepeaterconnectstwosegmentsofsameLAN.
Cannot connect two LAN’s of different protocols.

15. Hubs
It is simply a multiport repeater.
• Passive Hubs
• Active Hubs
• Intelligent Hubs

17. References
Data Communication
Wikipedia
Google Images
Lecture Notes

18. ?
THANK YOU.