Network Fundamentals Chapter 7 Study Guide
Data Link Layer
V 4.0
7.1.1
What are the 2 basic
services the Data Link layer
provides?
List and define the 4
specific terms associated
with the Data Link layer?
7.1.1.2 What happens the frame as
moves from source to
destination?
7.1.2
Define Media Access
Control.
7.1.3
What can the control
information tell you?
List and define the three
elements of a Data Link
Layer Frame.
7.1.3.2 List and define the 5 typical
field types.
7.1.4
What is the most common
physical device that is used
for the Data Link Layer?
7.1.4.2 Describe the two sublayers
of the Data Link Layer.
-Allows the upper layers to access the media
using techniques such as framing
-Controls how data is placed onto the media
and is received from the media
-Frame - The Data Link layer PDU
-Node - The Layer 2 notation for network
devices connected to a common medium
-Media/medium (physical)* - The physical
means for the transfer of information between
two nodes
-Network (physical)** - Two or more nodes
connected to a common medium
usually a router - accepts frames from a
medium, decapsulates the frame, and then
forwards the packet in a new frame
appropriate to the medium of that segment of
the physical network.
processes by which network devices can
access the network media and transmit frames
in diverse network environments.
-Which nodes are in communication with each
other
-When communication between individual
nodes begins and when it ends
-Which errors occurred while the nodes
communicated
-Which nodes will communicate next
-Data - The packet from the Network layer
-Header - Contains control information, such
as addressing, and is located at the beginning
of the PDU
-Trailer - Contains control information added to
the end of the PDU
Start and stop indicator fields - The beginning
and end limits of the frame
Naming or addressing fields
Type field - The type of PDU contained in the
frame
Control - Flow control services
A data field -The frame payload
Swich/Bridge
The upper sublayer defines the software
processes that provide services to the Network
7.1.5
7.2.1
7.2.2
What are the two functions
of the Logical Link Control?
What are the two functions
of the Media Access
Control?
What are the 4
organizations that define the
Data Link standards?
What analogy is made with
the media access control?
What does the method that
media access control uses
depend on?
What are the two basic
media access control
methods for shared media?
What are two examples of
controlled media access?
What are two examples of
contention-based media
access?
Why can controlled media
access be inefficient?
What is CSMA?
7.2.3
7.2.4
7.2.5
layer protocols.
The lower sublayer defines the media access
processes performed by the hardware.
Places Information in the frame—Identifies
which network layer protocol is being used.
Provides Data Link layer addressing &
delimiting of data according to physical
Signaling requirements of medium ,
ISO—IEEE—ANSI—ITU-
Regulating the placement of data frames onto
the media is known as media access control.
Media Sharing. Topology
Controlled
Contention based
Deterministic---throughput
process to first detect if the media is carrying a
signal
What is a data collision?
the data sent by both devices will be corrupted
and will need to be resent.
What is CSMA/CD?
monitors the media for the presence of a data
signal.
What is CSMA/CA?
examines the media for the presence of a data
signal.
Define Half-Duplex.
devices can both transmit and receive on the
media but cannot do so simultaneously.
Define Full-Duplex.
both devices can transmit and receive on the
media at the same time
Define physical topology.
arrangement of the nodes and the physical
connections between them.
Define logical topology.
way a network transfers frames from one node
to the next.
What logical and physical
Logical=network is closely related to the
topologies are typically used mechanism used to manage network access
in networks?
The physical or cabled topology of a network
will most likely not be the same as the logical
topology.
Define point-to-point
Connects two nodes directly together.
topology.
7.2.5.2 Define virtual circuit.
7.2.6
7.2.7
7.3.1
7.3.2
7.3.3
7.3.4
Which type of topology is
used to determine the
media access control?
Define logical multi-access
topology.
What are the three types of
media access control can
be used in a multi-access
topology?
How does a data flow in a
ring network?
What are the three basic
parts of a data link layer
frame?
What are the typical fields in
the frame header?
Which part the network
(WAN/LAN) is the data link
address used in delivering?
What is the difference
between Data Link Address
and Logical Address?
Does a point-to-point link
need a data link address?
Define error detection.
Define Frame Check
Sequence.
How could the CRC be
correct and the frame
contain errors?
Do all protocols support
using the FCS to determine
errors?
7.3.5
What Layer 2 protocols will
we study in this course?
Which usually performs at a
higher bandwidth, LAN or
WAN?
7.3.5.2 What do Ethernet standards
define?
What is the data link
address?
How is the data link address
Logical connection created within a network
between two network devices.
Logical Point-to-point topology
are typically CSMA/CD or CSMA/CA.
However, token passing methods can also be
used.
CSMA/CD CSMA/CA ..Token passing
each node in turn receives a frame. If the
frame is not addressed to the node, the node
passes the frame to the next node
Header –Data--Trailer
Start frame-Source&DestinationPriorty/Quality-Type-Logical Connection
control-Physical link-flow control-Congestion
Logical topology
Data link address is only used for local delivery
No
trailer is used to determine if the frame arrived
without error
used to determine if errors occurred in the
If two frames values are the same CRC reads
it as arrived
No
Ethernet = PPP=HDLC = Frame relay= ATM
LAN
family of networking technologies that are
defined in the IEEE 802.2 and 802.3 standards
the frame structure is nearly identical for all
speeds of Ethernet.
identify the source and destination nodes
expressed?
7.3.5.3 What type of architecture
does PPP use?
What are options available
to use with PPP?
7.3.5.4 What is the standard used
for wireless LANs?
What services are
supported by 802.11?
7.4.1.2 Examine each of the
processes and take notes.
Develop questions on any
step you do not understand.
Layered
Authentication, compression
802
IEEE