The OSI Model Flashcards
1
Q
All People Seem To Need Data Processing
A
Application
Presentation
Session
Transport
Network
Data Link
Physical
2
Q
What is a Protocol Data Unit (PDU)
A
Is what the information is called at each layer.
3
Q
Application Layer
A
- Delivers appropriately formatted payload to the correct instance of an application.
- Includes protocols such as HTTP, SMTP, DNS
- If an application needs to interface with the network, it’s going to engage the Application layer of the OSI model.
- The application layer is the gateway to the next two layers
4
Q
Presentation Layer
A
- Converts data into different formats.
- Compression and Encryption are often handled here.
- When payload passes through here, its encapsulated and Layer 6 header is added.
- When payload is going up to App layer, the layer 6 header is removed.
- Presentation layer puts the data into a format we understand (GIF, JPEG, etc.)
5
Q
Session Layer
A
- Data traverses the Session Layer
- Establishes and maintains communications.
- Layer 5 header is added before sent to Layer 4, removed before sent to Layer 6.
6
Q
Transport Layer
A
- Applies flow control and error detection.
- Includes protocols TCP/UDP
- Responsible for error free delivery between devices
- Data is encapsulated and Layer 4 header is added, removed prior to heading to Layer 5.
- Information is called a segment.
7
Q
Network Layer
A
- Includes devices like Routers
- Protocols (IPv4/6, IPX)
- Logical addressing and routing on a network.
- Encapsulated at Layer 3 header added before going to 2/ removed when going to 4.
- Information called a packet
8
Q
Data Link Layer
A
- Is responsible for managing physical Addressing (MAC Addresses)
- Includes devices like Switches.
- Protocols Ethernet, Frame Relay, Token Ring, PPP, CDP
- Information called Frame, Layer 2 header added/removed here.
9
Q
Physical Layer
A
- Defines how Bits are transferred.
- Information called Bits.
- Devices include: NIC cards, Hubs, repeaters
