Week 2 - Network Protocols

Question 1

1. )Explain A Unicast Transmission
2. ) Explain A Multicast Transmission.
3. ) Explain a Broadcast.

Answer 1

1. ) Unicast is to a single device! Can be defined as 1-1 communication to a device on a LAN.
2. ) Multicast broadcasts to a group of devices on a LAN, but not every single one! Think of it as a subset of clients!
3. ) Broadcast is to all possible devices operating on a LAN. It can be thought as a 1-all communication.

Question 2

1.) What are Network Protocols responsible for? (5 points)

Answer 2

1. )
   - Performing different functions.
   - Defines the structure and formatting of messages.
   - Defines how networking devices share information.
   - Error and System message management.
   - The setup and maintenance of data transmission “sessions”

Question 3

What function does an application perform within a network? (E.g. HTTP) (Three Points)

Answer 3

• Formatting of data to make it transmittable across the network and readable on both ends.
• Controls how processes such as downloading a webpage or sending an email are performed.
• Acts as the interface between the user and the network!

Question 4

What function does a transport protocol have? (E.G. TCP)

Answer 4

• Checks to ensure data has or hasn’t been received.

- Marks packets in the order they are meant to be read.

Question 5

What function does Internet Protocol (IP) have (Two Points)?

Answer 5

• Manages the path data is sent along through the use of an IP address. Controls how data is sent across networks via routing!
• Manages the transmission of traffic to and from outside the Local Area Network.

Question 6

What Do The Data Link Protocols Manage? (Three Points)

Answer 6

• The addressing and transmission of data across a local network through use of a Media Access Control (MAC) address.
• Data Framing - Packets and are encapsulated further into frames.
• Error Detection and Handling - Lowest later Error detection - Checks to see if data received correctly.

Question 7

What do the Physical Protocols Handle? (4 Points)

Answer 7

• Defines how the data is being sent and how the cabling, connectors, wireless transceivers, network interface cards etc operate.
• Encodes and signals data from frames to bits which can be transmitted across the network.
• The transmission of data.
• The topology, both physical and logical.

Question 8

What is a Protocol Suite?

Answer 8

A set of rules that work together to help solve a problem (E.g. Checking to see if the line is clear before making a broadcast).

Question 9

Why is a layered model for network Protocols a good idea?

Answer 9

• It specifically defines how and when data is moved and altered as it goes through the process of being transmitted.

Question 10

1. How many layers does the TCP/IP model contain?

2. Name The Layers Of The TCP/IP Model In Order:

Answer 10

1. ) 4
2. )

• Application Layer
• Transport Layer
• Internet Layer
• Network Access Layer.

Question 11

1. ) How Many layers does the OSI model contain?

2. ) List Each Layer In Order From Top To Bottom.

Answer 11

1.) 7

2. )
   - Application
   - Presentation
   - Session
   - Transport
   - Network
   - Data Link
   - Physical.

Question 12

1. ) In terms of size, what must occur to data in order to be sent across the network.
2. ) Data sent across the network must meet the …………… and …………….. …………. requirements of the network.
3. ) Which is the process of adjusting the size of data for network transmission defined as?

Answer 12

1. ) Long sets of data are broken down into smaller, individual pieces.
2. ) must meet the maximum and minimum size requirements of the network.
3. ) Segmentation.

Question 13

1. ) Define encapsulation
2. ) In encapsulation, the transmitted message is switched from ……… to ….
3. ) What structure does encapsulation build at each layer.

Answer 13

1. ) Taking a segment relating to a certain level in the transmission process and including another data structure within it. This is achieved through the addition of a layer specific header to the current set of data.
2. ) Data to bits.
3. ) A Protocol Data Unit (PDU) forms.

Question 14

1. ) Define decapsulation.

2. ) In decapsulation, the transmitted message is swapped from …. to ………

Answer 14

1. ) Decapsulation splits the transmitted message into its respective PDU’s at each layer and hands it to the node within the transmission that is responsible for handling the specific process unit (E.g. the router decapsulation the Internet layer and Checks the IP destination and source IP address.
2. ) Bits to Data.

Question 15

What does encapsulation endure lower layers can’t do.

Answer 15

1.) It ensures lower layers cannot read the data that is not relevant to their functionality .

Question 16

1. ) State the benefits of segmenting a message? (Two)

2. ) What is the main disadvantage of segmenting a message?

Answer 16

1. )
   - Different conversations can be interleaved through multiplexing.
   - Network communication is more reliable.
2. )
   - The complexity of transmitting data is increased.

Question 17

1. ) In encapsulation, Which is the unit which contains the header Information for each particular layer of transmission?
2. ) Name each of the PDU’s which occur across the OSI and TCP/IP models and place them in order starting from when they are first encapsulated at the Application later down to the Physical Layer.

Answer 17

1. ) Protocol Data Unit (PDU)
2. )

• Data (Application, Presentation and Session Layer)
• Segments (Transport Layer)
• Packets (Internet Layer)
• Frames (Data Link Layer)
• Bits (Physical Layer)

Question 18

Briefly Explain What can be found in the Application layer PDU.

Answer 18

Encoded Application Data (e.g. The actual content of the file to be sent)

Question 19

Briefly Explain What can be found in the Transport layer PDU.

Answer 19

The destination and source ports the data is to be transmitted across (They define what the ‘conversation’ the source and destination are engaging in is about, E.G if the data has come from a web server or is AppleTalk data)

Question 20

Briefly Explain What can be found in the Network PDU.

Answer 20

1.) The destination and source logical addresses (IP addresses)

Question 21

Briefly Explain What can be found in the Data Link PDU.

Answer 21

Destination and source physical addresses (MAC address)

Question 22

1.) Briefly Explain What can be found in the Physical PDU

Answer 22

Timing and synchronisation bits.

Question 23

If a default gateway is incorrectly configured, what can the user no longer do?

Answer 23

• Communicate with hosts in other networks.

Question 24

Which layer of the OSI model defines services to segment and reassemble data for individual communications between end devices?

Answer 24

Transport Layer

Question 25

Which address is used to deliver data to a host on a remote network?

Answer 25

- Destination IP address.

Question 26

A packet who’s source IP is on the same network as it’s destination host IP will:

Answer 26

Not leave the network.

Question 27

What general term is used to describe a piece of data at any level in the network?

Answer 27

- A Packet.

Question 28

What is the default gateway?

Answer 28

The IP address of the router interface which all data passes through to leave the network within a LAN.

Question 29

What type of delivery uses data link layer addresses?

Answer 29

Local - The MAC address is only used to search local networks! (If no devices has the MAC address locally, the IP address only used to get off the network and search others)

Question 30

1. ) Define an ARP request (Network Access/Internet Layer) 2. ) What MAC address indicates a broadcast request? 3. ) How does ARP assist in transmitting data off the local network?

Answer 30

1. ) - A system needs to know the MAC address of the interface it is sending its data to. - It knows the IP, so it sends out an ARP request. This essentially asks “Who has the IP address 192.168.x.x?” via an ARP request which contains a MAC address of “FF-FF-FF-FF-FF-FF” - An intermediate device (e.g. a Switch) receives the request and floods each of its ports with a ARP request of its own. This asks “If you have this IP address, respond with your MAC” - The device with the IP address responds with its MAC address. All others drop the packet. - The switch updates its ARP table and responds to the source by telling it the MAC address the data is headed for. - The host sends the packets it needs. 2. ) FF-FF-FF-FF-FF-FF 3. ) The host learns the MAC of its default gateway. The router then handles any further routing processes to get the packet off the network.

Question 31

Which addresses change as they travel across the different network devices?

Answer 31

- Source and Destination MAC.

Question 32

1.) What are Proprietary Protocols?

Answer 32

2. They are developed and owned by a single private business or organisation. They often tend to operate well on particular devices (Think Apple and Appletalk), but may often not be supported by other competitors. Open Standard Protocols are industry accepted protocols that are NOT VENDOR SPECIFIC. They are often collaborative efforts by a group of corporations. These include IP, TCP, UDP. 3. ) Open Standard Protocols allow for greater interoperability between different proprietary brands of software and hardware. IP will work on a device no matter what it is.

Question 33

Briefly State The Function of the Application Layer

Answer 33

Network Process to Application | The user interface - User interacts with the layer to interact with the network

Question 34

Briefly State The Function of the Presentation Layer

Answer 34

Data Representation And Encryption. (Often the layer at which the Operating System works at - Translates between Application layer

Question 35

Briefly State The Function of the Session Layer

Answer 35

Interhost Communication. (The layer establishes a session between hosts, manages handshaking and duplexing) In summary, it controls dialogs between computers.

Question 36

Briefly State The Function of the Transport Layer

Answer 36

End to end connections and reliability. | Provides transparent transfer of data through TCP and UDP - Reliable and unreliable connections

Question 37

Briefly State The Function of the Network Layer

Answer 37

Path Determination and Logical Addressing.

Question 38

Briefly State The Function of the Data Link Layer

Answer 38

Physical Addressing (MAC and LLC)

Question 39

Briefly State The Function of the Physical Layer

Answer 39

Media, Signal and Binary Transmission.