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Tutorial 4 For FCN

This document discusses the data link layer of the OSI model. It contains questions about: 1) Logical Link Control (LLC) and its role in interacting with upper layers and assisting with frame creation. 2) Identifying the start of frame and frame trailer flags in a data frame diagram. 3) Media access control as the sublayer that defines media access processes performed by hardware. 4) Network connection methods like Ethernet and WiFi used in LANs, and the shared access method they employ. 5) Changes required of network layer protocols without a data link layer, such as IP needing to handle physical addressing.

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SHU LING FONG
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132 views4 pages

Tutorial 4 For FCN

This document discusses the data link layer of the OSI model. It contains questions about: 1) Logical Link Control (LLC) and its role in interacting with upper layers and assisting with frame creation. 2) Identifying the start of frame and frame trailer flags in a data frame diagram. 3) Media access control as the sublayer that defines media access processes performed by hardware. 4) Network connection methods like Ethernet and WiFi used in LANs, and the shared access method they employ. 5) Changes required of network layer protocols without a data link layer, such as IP needing to handle physical addressing.

Uploaded by

SHU LING FONG
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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AACS2034 Fundamentals of Computer Networks

Tutorial 4: Data Link Layer (OSI Model)

Question1
(a) Give a term that related to upper sublayer of layer two and briefly describe that term.(3 marks)
Logical Link Control (LLC), aka IEEE8o2.2
- It helps the Data Link Layer to interact with upper layer
- It handles software processes like error control, flow control, assists in creating frames.
- LLC correspondents with the driver of Network Interface Card (NIC) (MAC deals with the network
adapters)
(b) The following figure shows a frame of data link layer.

Figure 1: A structure of a frame

(i) Identify a header of a frame that labeled as “A” from Figure 1 and state the function of that flag.
(2 marks)
Start of Frame
- A Series of bit patterns which represent the beginning of a frame

(ii) Based on Figure 1, identify a frame trailer that had indicated as “B”. List a role of that flag. (2 marks)

(c) Protocol Data Unit (PDU) of a message in Data Link Layer is called frame. A frame consists of three
portions. There are referred to header, data and trailer.

(i) Identify a sublayer of Data Link Layer that defines the media access processes performed
by the hardware. (1 mark)
1 updated by Ts. Carolyn Ting Hie Choon on 25.5.2020

AACS2034 Fundamentals of Computer Networks

Tutorial 4: Data Link Layer (OSI Model)

(ii) Identify and briefly describe TWO (2) fields that related to the header of a frame. (6
marks)

(iii) What is the purpose of stop frame that located at the trailer of a frame? (2 marks)

Q2. The Figure 2 shows a network topology on how computers can communicate across LAN and
WAN via different types of physical media and Layer 2 protocols. Answer the following
question based on the Figure 2.

2 updated by Ts. Carolyn Ting Hie Choon on 25.5.2020

AACS2034 Fundamentals of Computer Networks

Tutorial 4: Data Link Layer (OSI Model)

(i) “A” and “B” are two different popular network connection methods for LAN. Identify the type
of connecting media and the IEEE Networking Standard of LAN “A” and “B” respectively.
(4 marks)

(ii) There are two types of access method in LAN topology. Which access method is used for both
“A” and “B”? (1 mark)

(b) If the data link layer didn’t exist, what changes would be required of a network layer
protocol such as Internet Protocol (IP)? (6 marks)
3 updated by Ts. Carolyn Ting Hie Choon on 25.5.2020

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