OSI TCP/IP model Flashcards
The 4 layered TCP/IP model layers
Application (Application, Presentation, Session)
Transport (Transport)
Internet (Network)
Network Access (Data Link, Physical)
Application Layer.
Brief Description and layer number
Allows a client application to access resources on a network using various Protocols
Layer 7
Data Link Layer
Frames data for placement on the local network link
Layer 2
Data Link Layer’s Protocol Data Unit (PDU)
Frames
Network Layer’s Protocol Data Unit (PDU)
A Packet
Transport Layer’s Protocol Data Uni (PDU)
A Segment
Layer 5 and above Protocol Data Unit
Data
Physical Layer’s Protocol Data Unit (PDU)
A bit
Encapsulation and Decapsulation
Data travelling down each of the OSI layers. At each layer a header and sometimes a trailer is added to the original data.
Once it reaches the physical layer it is sent across the network as a signal to the receiving device and Decapsulation does the same process but in reverse order.
Which Layer do Hubs and Repeaters live on ?
Layer 1
Physical Layer
Only effective in small LANs
Layer 1
Physical
Layer 1 devices
Repeaters, Hubs
Layer 2
Data Link
Layer 2 Devices
Standard Switches (L2 Switches)
Layer 3
Network
Layer 3 Devices
Routers
Multi Layer Switches
Layer 4
Transport
Layer 5
Session
Layer 6
Presentation
Layer 7
Application
Layers of the OSI model. Top to bottom.
7) Application
6) Presentation
5) Session
4) Transport
3) Network
2) Data Link
1) Physical
Network Layer summary
Responsible for addressing and moving packets around the network
Layer 3
OSI Model Acronym for Layers
All People Seem To Need Data Processing
Physical Layer summary
Encodes bits into an appropriate signal for transmission on the physical medium
Layer 1
Presentation Layer Summary
Affects how data is presented for transmission across a network
Encryption, ASCII
Layer 6
Routers
Connect multiple networks together
Layer 3 - Network Layer
Uses IP addresses and routing tables
Session Layer
Opens, Maintains and closes a communication session.
Layer 5
Switches
Layer 2 - Data Link
Used within a LAN
Transport Layer
Segments and Sequences Data to be transported over the network.
Also provides error checking
Layer 4
What is the medium ?
The way in which digital devices are connected. e.g Phones transmitting through a wireless signal.
Cables. Fibre-optic, copper
Order the networking PDUs into the correct order (top to bottom) for encapsulation for transmission over a network connection.
Segments
Packets
Frames
Bits
This TCP Model layer would be the equivalent to the OSI Model’s Network layer
Internet
This TCP Model layer would be the equivalent to the OSI Model’s Data-Link and Physical layers
Network Access Layer
This TCP Model layer would be the equivalent to the OSI Model’s Transport layer
Transport Layer
This TCP Model layer would be the equivalent to OSI Model’s Application, Presentation and Session layers.
Application
NIC’s OSI Model Layer
Data Link
What does OSI stand for ?
Open Systems Interconnection.
Allows a client application to access resources on a network using various Protocols
Application Layer
Frames data for placement on the local network link
Data Link Layer
Data travelling down each of the OSI layers. At each layer a header and sometimes a trailer is added to the original data.
Once it reaches the physical layer it is sent across the network as a signal to the receiving device
Encapsulation
Layer that Routers & Multi Layer Switches live on ?
Layer 3
Network
Segments and Sequences Data to be transported over the network.
Also provides error checking
Transport Layer
Opens, Maintains and closes a communication session.
Session Layer
Responsible for addressing and moving packets around the network
Network Layer
Encodes bits into an appropriate signal for transmission on the physical medium
Physical Layer
Affects how data is presented for transmission across a network
Encryption, ASCII
Presentation Layer
