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Flashcards in OSI Layers Facts Deck (19):
1

Application (Layer 7)

* Integrates network functionality into the host operating system and enable network services
* Does not include specific applications that provide services, but rather the capability for services to operate on the network
* Most application layer protocols operate at multiple layers down to the Session and even Transport layers but are classified as application layer protocols because they start at the application layer

2

Services associated with layer 7

* HTTP
* Telnet
* FTP
* TFTP
* SNMP

3

Presentation (Layer 6)

* formats or presents data into a compatible form for receipt by the application layer or the destination system

4

What does layer 6 ensures?

* Formatting and translation of data between systems
* Negotiation of data transfer syntax between systems by converting character sets to the correct format
* Encapsulation of data into message envelopes by encryption and compression
* Restoration of data by decryption and decompression

5

Session (Layer 5)

* manages the sessions in which data are transferred

6

Functions of layer 5

* Management of multiple session (each client connection is called a session) A server can concurrently maintain thousands of sessions
* Assignment of session ID number to each session to keep data streams separate
* The setting up, maintenance, and tearing down of communication sessions

7

Transport (Layer 4)

* Provides a transition between the upper and lower layers of the OSI model making the upper and lower layers transparent from each other.

8

Functions of layer 4

* End-to-end flow control
* Port and socket numbers
* Segmentation, sequencing, and combination
* Connection services, either reliable (connection-oriented) or unreliable (connectionless) delivery of data
**** Data at the Transport layer are called segments ****

9

Network (Layer 3)

* Describes how data are routed across networks and on to destinations

10

Functions of layer 3

* Identifying host and networks by using logical addresses
* Maintaining a list of known networks and neighboring routers
* Determining the next network point to which data should be sent. Routers use a routing protocol that takes into account various factors such as # of hops in the path, link reliability, to select the optimal path for data
***** Data at the Network Layer are called packets *****

11

Data Link (Layer 2) can is broken down to what to layers?

* Logical Link Control (LLC)
* Media Access Control (MAC)

12

Data Link (Layer 2)

* defines the rules and procedures for hosts as they access the Physical Layer.

13

Functions of layer 2

* How hosts on the network are identified (physical or MAC address)
* How and when devices can transmit on the network medium (media access control and logical topology
* How to verify that the data received from the Physical layer are error free (parity and CRC)
* How devices control the rate of data transmission between host (flow control)
**** Data at the Data Link layer are called frames ****

14

Physical (Layer 1)

* Set standards for sending and receiving electrical signals between devices

15

Functions of layer 1`

* How digital data (bits) are converted to electric pulses, radio waves, or pulses of light
* Specifications for cables and connectors
* The physical topology
**** Data at the Physical layers are called bits ****

16

TCP/IP Model

* Application
* Host-to-Host
* Internet
* Network Access

17

Application

* Corresponds to the Session and Application layers of the OSI model.
* Protocols associated with the Application layer include FTP, HTTP, Telenet, SMTP, DNS, and SNMP

18

Host-to-Host

* Comparable to the Transport layer of the OSI model.
* Responsible for moving packets through a network
* This involves addressing hosts and making routing decisions to identify how the packet traverses the network
* Protocols associated Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP), and Internet Group Management Protocol (IGMP)

19

Network Access

* Corresponds to the Physical and Data Link layers
* Responsible for describing he physical layout of the network and how messages are formatted on the transmission medium