3 - OSI + TCP/IP Model Flashcards
1
Q
OSI Model
A
- 7 layers
- Each layer servers the layer above
- When a packet is sent, it starts at layer 7 and works it’s way down
2
Q
OSI Layers
A
7 - Application 6 - Presentation 5 - Session 4 - Transport 3 - Network 2 - Data Link 1 - Physical
3
Q
OSI v TCP/IP
A
Application —
Presentation —> Application
Session —
Transport —> Transport
Network —> Internet
Data Link —> Network Access
Physical —>
4
Q
PDU
A
Protocol Data Unit
- A PDU is the entire communication from layer 7 to layer 1
- They are what’s exchanged in transfer
- PDU is correct terminology but everyday slang is packet
5
Q
TCP/IP Terminology
A
- Application layer = Data
- Transport layer = Segment
- Internet = Packet
- Network Access = Frame
6
Q
OSI Layers
A
7 to 5 don’t overly concern network engineers
7
Q
OSI Layer 7
A
Application
- Provides network services to the applications of the user
8
Q
OSI Layer 6
A
Presentation
- Ensures the data sent by the application layer is readable by the application layer of another host
- It can translate between multiple formats using a common format
9
Q
OSI Layer 5
A
Session
- Establishes, maintains and terminates sessions between 2 hosts
- Manages data exchange between presentation layers
10
Q
OSI Layer 4
A
Transport
- Main characteristics are whether TCP or UDP is used and port numbers
- Provides segmentation services which breaks down large amounts of data into smaller, more manageable sized segments
- Smaller segments means they are less likely to incur transmission errors
11
Q
OSI Layer 3
A
Network
- Manages the connectivity of hosts by providing logical addressing
- Logical Addresses = IP Addresses
- Provides path selection between hosts too
- Routers operate on layer 3
12
Q
OSI Layer 2
A
Data Link
- Provides physical addressing = MAC Addresses
- Defines how the data is formatted for transmission and how access to physcial media is controlled
- Typically includes error detection + correction
13
Q
OSI Layer 1
A
Physical
- Concerns the physical components of the network ie cables
- Defines specifications needed for activating, maintaing and deactivating physical links
- E.g. voltage levels, max transmission distances, physical connectors