OSI model Flashcards
1
Q
What does the physical layer do?
A
- defines all electrical and physical specifications for devices.
- major functions.
- establishment and termination of connections.
- connection resolution and flow control of communications resources.
2
Q
What are the 7 different layers?
A
1) physical
2) data link
3) network
4) transport
5) session
6) presentation
7) application
3
Q
What does the data link layer do?
A
- controls data transfer between network entities.
- performs error detection and correction.
- uses physical/ flat addressing
4
Q
What are the 2 types of addressing/ what do they do?
A
- flat addressing
- hierarchal addressing.
flat- do not provide anything other than a unique identifier. they provide no real info about where the object being addressed resides.
hierarchal- provide layers/ a hierarchy to the address that provides info about where the addressed object exists within hierarchy.
5
Q
What does the network layer do?
A
- performs network routing, flow control, segmentation and error reduction functions.
- the router and firewall operate this layer.
- uses local addressing scheme.
6
Q
What does the transport layer do?
A
- provide transport transfer of data between end users.
- controls reliability of given link
- some protocols are stateful and connection oriented (cookies)
7
Q
What does the session layer do?
A
- provides mechanism for managing the dialogue between end user applications processes.
- provides for either duplex or half duplex operation
- responsible for setting up and tearing down TCP/IP sessions.
8
Q
What does the application layer do?
A
- closest to the user
- provide semantic conversion between associated application processes.
- interfaces directly to and performs common application services for the application processes.
9
Q
What does the presentation layer do?
A
- little to do with PowerPoint.
- converts between data formats
- like an English to French translator.
