OSI Layers Facts Flashcards Preview

Test Out Network + > OSI Layers Facts > Flashcards

Flashcards in OSI Layers Facts Deck (19):

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


Services associated with layer 7

* Telnet


Presentation (Layer 6)

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


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


Session (Layer 5)

* manages the sessions in which data are transferred


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


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.


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 ****


Network (Layer 3)

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


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 *****


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

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


Data Link (Layer 2)

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


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 ****


Physical (Layer 1)

* Set standards for sending and receiving electrical signals between devices


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 ****


TCP/IP Model

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



* 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



* 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)


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