1A Comparing OSI Model Network Functions

Question 1

Acronym Used to remember OSI model from bottom up

Answer 1

Please Do Not Throw Sausage Pizza Away

Question 2

Acronym Used to remember OSI model from top to bottom

Answer 2

All People Seem To Need Data Processing

Question 3

OSI Model Layers

Answer 3

7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical

Question 4

Network Protocol 2 principal functions

Answer 4

Addressing & Encapsulation

Question 5

Addressing

Answer 5

Describing where data messages should go.

Question 6

Encapsulation

Answer 6

Describing how data messages should be packaged for transmission. Similar to an envelope for a letter with the distinction that each layer requires its own envelope.

Question 7

OSI reference model

Answer 7

Open Systems Interconnection - promotes understanding of how components in a network system work.

Question 8

Same layer interaction

Answer 8

protocol running at each layer communicates with its equivalent (or peer) layer on the other node.

Question 9

Adjacent Layer Interaction

Answer 9

Transmit or receive a communication on each node, each layer provides services for the layer above and uses the services of the layer below.

Question 10

Layer 1

Answer 10

(Physical Layer) responsible for transmission and receipt of the signals that represent bits of data from one node to another.

Question 11

Devices that operate at the Physical Layer include

Answer 11

Transceiver, Repeater, Hub, Media converter, Modem

Question 12

Transceiver

Answer 12

The part of the network interface that sends and receives signals over network media

Question 13

Repeater

Answer 13

A device that amplifies an electronic signal to extend the maximum allowable distance for a media type

Question 14

Hub

Answer 14

A multiport repeater, deployed as the central point of connection for nodes

Question 15

Media converter

Answer 15

a device that converts one media signaling type to another (ex: copper wire to fiber optic)

Question 16

Modem

Answer 16

A device that performs some type of signal modulation and demodulation, such as sending digital data over an analog line. Creates a physical connection to another network.)

Question 17

Layer 2

Answer 17

(Data Link Layer) Responsible for transferring data between nodes on the same logic segment. Organizes the stream of bits arriving from the physical layer into structured units called frames. Frames contain a network layer packet as its payload. Layer 2 adds control info to payload in form of header fields. Fields include source & destination hardware addresses + basic error check making sure received frame is intact.

Question 18

Layer 2 devices

Answer 18

NIC, Bridge, Switch, Wireless Access Point (AP)

Question 19

Logical Topology

Answer 19

At the Data Link Layer (L2) segment is one where all nodes can send tragic to one another using hardware addresses, regardless of whether they share access to the same media. A Layer 2 segment might include multiple physical segments.

Question 20

Layer 3

Answer 20

(Network Layer) - responsible for moving data around a network of networks, known as an internetwork or the internet. Moves info around by using logical network and host IDs.

Question 21

Layer 3 devices

Answer 21

Router, basic firewall (packet filtering firewall)

Question 22

Layer 4

Answer 22

Transport Layer - AKA the end-to-end or host-to-host layer. can understand payload/data itself. identifies each type of network app by assigning it a port number. Ex: data from HTTP web app is identified as port 80. Tags segments with application port numbers and passes it on to the network layer for delivery.

Question 23

Layer 4 PDUs

Answer 23

Segments

Question 24

PDU (network not hardware)

Answer 24

Protocol Data Unit - A unit of information transmitted between entities on a computer network.

Question 25

First 3 Layers of OSI Models are primarily concerned with…

Answer 25

moving frames and datagrams between nodes and networks. only read the header of the data packet.

Question 26

Layer 4 Devices

Answer 26

Load Balancer, Advanced Firewall, Intrusion Detection System (IDS)

Question 27

Layer 5

Answer 27

Session Layer - most app protocols require exchange of messages b/w client and serer - this exchange is called a session or dialog. Session layer represents functions that administer process of establishing a dialog, managing data transfer and ending the session.

Question 28

Layer 6

Answer 28

Presentation Layer - Supports data compression and encryption. transforms data between the format required for the network ad the format required for the app.

Question 29

Layer 7

Answer 29

Application Layer - doesn’t encapsulate or provide services to any protocol. Provides an interface for software programs on network hosts.

Question 30

Upper Layer Protocols provide…

Answer 30

most of the services that make a network useful rather than just functional, including web browsing, email and communications, directory lookup, remote printing and database services.

Question 31

PDUs at each layer

Answer 31

Layer 4 - Segment
Layer 3 - Datagram
Layer 2 - Frame
Layer 1 - Transceiver

Question 32

Devices used at each layer

Answer 32

Layer 3 - basic firewall, router
Layer 2 - Bridge, Switch, Access point?
Layer 1 - Cable, Media Converter, Hub, Access point?

Question 33

What Layer are IP addresses introduced?

Answer 33

Layer 3 - Network

Question 34

What layer are MAC addresses/EUIs introduced?

Answer 34

Layer 2 - data link

Question 35

At which OSI layer is the concept of a port number introduced?

Answer 35

Transport

Question 36

At which Layer of the OSI model is no header encapsulation applied?

Answer 36

Physical

Question 37

What component performs signal amplification to extend the maximum allowable distance for a media type?

Answer 37

A repeater

Question 38

Which OSI layer packages bits of data from the physical layer into frames?

Answer 38

Data Link

Question 39

True or False? The session layer is responsible for passing data to the network layer at the lower bound and the presentation layer at the upper bound.

Answer 39

False, the session layer is between the transport and presentation layer