Lesson 2-3: Ethernet Basics

Lesson 2-3: Ethernet Basics
Unit 2: LAN Configurations
Lesson 2-3: Ethernet Basics
At a Glance
Ethernet LAN topology is currently the most common network
architecture. Ethernet topologies are generally bus and/or bus-star
topologies. Ethernet networks are passive, which means Ethernet hubs do
not reprocess or alter the signal sent by the attached devices. Ethernet
technology uses broadcast topology with baseband signaling and a control
method called Carrier Sense Multiple Access/Collision Detection
(CSMA/CD) to transmit data. The IEEE 802.3 standard defines Ethernet
protocols for (Open Systems Interconnect) OSI’s Media Access Control
(MAC) sublayer and physical layer network characteristics. The IEEE
802.2 standard defines protocols for the Logical Link Control (LLC)
sublayer. A solid understanding of Ethernet basics is necessary for all
network personnel.
What You Will Learn
After completing this lesson, you will be able to:
•
Describe Ethernet topology.
•
Explain how CSMA/CD is used within an Ethernet LAN.
•
Compare and contrast two Ethernet frame types.
•
Describe the relationship between IEEE Ethernet standards and the
OSI model.
•
Troubleshoot an Ethernet problem.
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Tech Talk
178
•
Back Off ModeA waiting mode in Ethernet topology where
computer devices wait a specific amount of time before attempting to
retransmit data after they have detected a collision.
•
BandwidthThe amount of data a transmission medium can carry.
•
BasebandA data transmission method in which the entire
bandwidth of the cable is used to transmit a single signal. Only one
signal can be transmitted at a time.
•
BroadbandA data transmission method in which cable capacity is
divided into multiple independent bandwidth channels. This allows
several data transmissions to occur simultaneously over the cable.
•
BusA bus is a common pathway (usually copper wire or fiber-optic
cable) between multiple devices such as computers. A bus is often used
as a backbone between devices.
•
Carrier SenseThe ability to detect or sense the presence of other
data transmissions on a network. In Ethernet technology, this ability
helps avoid or prevent collisions.
•
Collision DetectionThe ability to detect whether any other devices
are trying to access the network simultaneously.
•
Collision DomainAll devices on the same Carrier Sense Multiple
Access/Collision Detection wire segment are considered one collision
domain. A collision in one domain does not affect any other domain on
the network.
•
Contention BasedIn Ethernet topology, a computer device must
wait for a turn to use the network. Computer devices must contend
with other devices for network access. This means that all devices have
an equal opportunity to send signals. No device has priority.
•
EthernetA LAN topology based on Carrier Sense Multiple
Access/Collision Detection (CSMA/CD).
•
Network Operating System (NOS)Software that allows computer
devices to interconnect in order to transmit data across media.
•
Passive HubA central connecting device in a network that joins
wires from several stations, but does not provide signal processing or
regeneration.
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Ethernet Origins
Ethernet topology, which is based on bus and bus-star physical
configurations, is currently the most frequently configured LAN network
architecture. A bus is a common pathway (usually copper wire or fiber
cable) between multiple devices such as computers. A bus is often used as
a backbone between devices. It is a technology that has been evolving for
more than 25 years and is still evolving to meet the ever increasing and
changing needs of the internetworking community.
Digital Equipment Corporation and Xerox (DIX) worked together to
develop the first Ethernet standards. These standards are the DIX
Ethernet standards and are still in use today. As Ethernet topology
became more popular, industry-wide standards became necessary. In
1985, the IEEE adopted the current Ethernet standards. These standards
are called the IEEE 802.2 and 802.3 standards. They differ slightly from
the DIX standards, but both define the protocols for the physical and data
link layers of the OSI Model. These standards include cabling
specifications, frame format, and network access conventions.
Ethernet is a passive, contention-based broadcast technology that uses
baseband signaling. Baseband signaling uses the entire bandwidth of a
cable for a single transmission. Only one signal can be transmitted at a
time and every device on the shared network hears broadcast
transmissions. Passive technology means that there is no one device
controlling the network. Contention-based means that every device must
compete with every o ther device for access to the shared network. In other
words, devices take turns. They can transmit only when no other device is
transmitting.
Ethernet popularity is a result of several factors. Ethernet technology is:
•
Inexpensive
•
Easy to install, maintain, troubleshoot and expand
•
A widely accepted industry standard, which means compatibility and
equipment access are less of an issue
•
Structured to allow compatibility with network operating systems
(NOS)
•
Very reliable
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Check Your Understanding
♦ Explain what is meant by passive, contention based, broadcast
technology that uses baseband signaling.
♦ Why is Ethernet topology currently the most frequently configured
LAN network architecture?
Ethernet Configuration and Communication
Ethernet Configuration
Ethernet is a broadcast topology that may be structured as a physical bus
or physical star with a logical bus.
Ethernet Physical Bus Topology
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The physical star with a logical bus is created with the use of a hub or
concentrator.
Ethernet Physical Star/Logical Bus Topology
Hub
Ethernet Communication
Communication protocols for Ethernet networks encompass both the datalink and physical layers of the OSI model. This lesson deals mainly with
the data-link layer, which is subdivided into a Media Access Control layer
and a Logical Link Control layer. Lesson 2-4 covers physical layer issues.
Ethernet uses Carrier Sense Multiple Access/Collision Detection
(CSMA/CD) when transmitting data. Carrier Sense allows a computer
device to “sense” whether or not another transmission is being “carried”
over the network. So, before a device sends data, it listens for a carrier
(jam) signal. If a carrier signal is detected, it waits until that transmission
is completed. Early DIX Ethernet did not have a carrier signal. Therefore,
a collision was not detected until the destination device received the
framed packet. The addition of a jam signal is one example of how
Ethernet technology has evolved.
Multiple Access means that all devices have equal access to the network.
Since Ethernet is contention-based, equal access to the network for all is
ensured. No device has priority over others, nor can it lock out any other
device connected to the network. Information can be transmitted at any
time by any device. All devices on the network receive the transmission
and check the framed packet’s destination address. If the destination
address matches the device’s address, the device accepts the data; if the
address does not match, the device simply ignores the transmission.
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Ethernet Collision
Device A
Device B
[
Device C
Collision Detection means that a sending device can “detect” simultaneous
transmission attempts. When two or more devices try to send data at the
same time, the signals collide. The illustration above shows devices A, B,
and C sending signals simultaneously, and a collision occurs. When this
happens, each device then transmits a jam signal, called a carrier, to alert
all other devices that a collision has occurred.
All devices then go into back off mode and wait a random amount of time
before attempting to retransmit data. The random time provision prevents
simultaneous retransmissions. All devices on the same Carrier Sense
Multiple Access/Collision Detection wire segment are part of the same
collision domain. A collision domain is defined as those devices that share
CSMA/CD of the same wire. Two or more collision domains are connected
together with an internetworking device such as a router, bridge, or
switch. With the use of internetworking devices, large networks are
created which include multiple collision domains.
When a collision occurs it affects all the devices on the same collision
domain. It does not affect devices on any other collision domains within the
same network. You can think of two collision domains as two roads that
are on different sides of a bridge. You can travel up to the bridge on either
side, but must get permission to cross the bridge. On an Ethernet collision
domain, frames of data travel within their own domain unless they need to
talk to a device on the other side of the bridge. If it is necessary to talk to a
device on the other side of a bridge, the bridge must give permission for the
frame to cross the bridge to reach the other collision domain. Bridges are
capable of this because they are store and forward devices: they store the
frame from the source domain until permission is granted to forward it.
The requirement is to keep traffic and collisions to a single collision
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domain whenever possible. Collision domains are also called segments in
Ethernet.
Ethenet Collision Domain
Data transmitted from one device to another on the same collision domain
will not affect any other collision domains. This allows each collision
domain to continue to transmit with no effect on each other except when a
device needs to talk to a device on another collision domain. When this is
required, the frame must be sent across one or more internetworking
devices to reach its destination. Each internetworking device must allow
the frame to pass. As the frame reaches each collision domain the port of
the internetworking device must contend for the right to transmit
according to the rules of CSMA/CD.
To better understand CSMA/CD, think about trying to make a telephone
call. Many of us have more than one telephone in our homes (a telephone
network). When you pick up the telephone to make a call, you “sense” a
dial tone or someone else on the line. If there is a dial tone, you proceed
with your call. If the telephone line is currently in use, you can not make a
call at this time and you try again later. This is similar to Ethernet
Carrier Sense protocols.
All telephones in the house can be used at any time to make calls. All
phones in the house have equal access to the telephone network. This is
comparable to Multiple Access.
Should two individuals in the house attempt to make a phone call
simultaneously, both hear dial tone; neither party senses a carrier,
(someone else on the line). However, like Ethernet technology, only
one individual can use the line at any one time. Both parties must
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hang-up and wait a random amount of time before making a second
attempt. This is how Ethernet’s Collision Detection protocols work.
In summary, a computer device checks to see if the transmission
media is busy, recognizes that multiple devices access the network,
and detects when a collision has taken place and goes into back off
mode.
Check Your Understanding
♦ Explain CSMA/CD in your own words.
♦ When your teacher asks a question in class, what might the result
be if everyone answered the question simultaneously?
♦ What rules do use in your class use to prevent simultaneous
responses?
♦ How is a polite conversation similar to CSMA/CD protocols?
Ethernet Frames
In Ethernet, both the data link and the physical layers are involved in the
creation and transmission of frames. The physical layer is related to the
type of LAN cabling and how the bits are transmitted and received on the
cable. The data link layer is divided into sublayers, the Logical Link
Control (LLC) and the Media Access Control layers (MAC). The frames
created by these layers contain several fields that are processed by
Network Interface Cards (NICs) in the sending and receiving devices.
Ethernet and the OSI Layers
Data Link
LLC
MAC
Physical
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The MAC sublayer address is the physical hardware address of the source
and destination computer. It is called the MAC layer address and should
not be confused with the network address. All devices on a LAN must be
identified by a unique MAC address. This sublayer controls which
computer devices send and receive the data and allows NICs to
communicate with the physical layer. IEEE 802.3 protocols control the
format of the MAC sublayer frame fields.
The next level of processing is the LLC sublayer. It is responsible for
identifying and passing data to the network layer protocol. Two LLC
protocols are IP and Novell’s IPX.
Frame Format
The two frame formats discussed in this lesson are DIX frames, which are
what the Internet uses, and IEEE 802.3 frames. It should be noted that if
one device uses an 802.3 NIC and the other device uses a DIX Ethernet
NIC, they would not be able to communicate with one another. Devices
must create the same Ethernet frame format in order to be compatible.
Although only the 802.3 IEEE frames format is outlined in the standard,
both formats are in use today. One way to tell them apart is that the DIX
frame has a “type” field, which defines the protocol used for the frame, and
IEEE 802.3 has a “length” field in its place. IEEE 802.3 also has
additional fields not used with the DIX format.
The DIX, also called Ethernet II, frame includes the following fields:
DIX Frame (Ethernet II)
8
bytes
Preamble
6
bytes
6
bytes
Destination Source
Address
Address
2
bytes
Type
46-1500
bytes
Data
4
bytes
FCS
The Preamble of the frame (the first 7 bytes) indicates the start of a new
frame and establishes synchronization conditions between devices. The
last byte, or start frame delimiter, always has a 10101011-bit pattern.
This byte indicates the start of a frame.
The Destination Address is the hardware (MAC) address of the receiving
device, and the source address specifies the hardware (MAC) address of the
sending device.
The Type field specifies the network layer protocol used to send the frame,
for example TCP/IP.
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The Data field is for the actual data being transmitted from device to
device. It also contains information used by the network layer and
indicates the type of connection.
The Cyclic Redundancy Check (CRC) checks that the frame is received free
from corruption.
IEEE 802.3 Frame Format
The IEEE standard was adopted in 1985. The 802.3 frame format is below:
7
bytes
1
bytes
Preamble SFD
6
bytes
6
bytes
Destination Source
Address
Address
2
bytes
46-1500
bytes
Length
Data and
Pad
4
bytes
FCS
Fields one and two perform the same function as the DIX preamble;
however, the fields are separate. The Start Frame Delimiter (SFD) has the
same 10101011-bit sequence found at the end of the DIX preamble. Both
formats use the same number of bytes to perform the synchronization of
the signals.
The Destination and Source Addresses can be either 2 or 6 bytes. Whether
2 or 6 bytes are used, all devices within the same network must use the
same format. IEEE protocols specify that a 10Mbs network must use 6
bytes. The 2 byte length is obsolete.
The Length field indicates the number of bytes in the data field. If the
data field is less than the required 46 bytes, a pad field is added to the data
frame. The bytes added for padding purposes are usually zeros.
The data field contains the data to be transmitted from device to device.
The Frame Check Sequence (FCS) field is used as an error detection
function. The error detection function is a calculation completed by both
the source and destination devices. If the calculations do not match, an
error is then generated.
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IEEE 802.2 LLC Frame
In between the length field and the data/pad field, is the 802.2 LLC field.
7
bytes
1
byte
Preamble SFD
6
bytes
6
bytes
Destination Source
Address
Address
1
byte
DSAP
2
bytes
46-1500
bytes
Length
Data and
Pad
1
byte
4
bytes
FCS
1
byte
SSAP Control
•
DSAP, destination service access protocol, is the protocol processing
layer the data is to be sent to.
•
SSAP, source service access protocol, is the protocol used to encapsulate
the data at the source.
•
Control is the field that defines the type of LLC frame this is.
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SNAP Format of 802.2
1
byte
DSAP
(AA)
1
byte
1
byte
3
bytes
SSAP
Control Organization
(AA)
2
bytes
EtherType
SNAP (Sub-Network Access Protocol) was created by the IEEE to identify
the Network layer protocol used. The original Ethernet version 2.0 Type
field had been reused as a Length field by the IEEE when creating the
IEEE 802.3 standard. SNAP was defined to enable this Length field to
remain while also allowing the vendor and protocol to be defined in the
first 40 bits of the Data field. Together, these two fields (Organization and
EtherType) are called the Protocol ID.
•
AA in the DSAP or SSAP fields indicates that the LLC field is using
SNAP format.
•
Control is the field that defines the type of LLC frame this is.
•
Organization is the field that indicates which organization created the
protocol identified in the EtherType field, though generally this is
coded as all zeros by most organizations.
•
EtherType is a two-byte identifier for the protocol being used to
encapsulate the data. For example, IP is indicated by the code 0x08-00,
ARP by 0x08-06 and NetWare IPX/SPX by 0x81-37.
Depending on how the vendor decided to manufacture the Ethernet
hardware, the hardware will create frames that are either DIX, 802.3, or
802.2 with SNAP.
Frame Types
There are three types of frames; each has a different purpose. The three
types are:
•
Unicast
•
Multicast
•
Broadcast
If the first bit of the frame is 0, it is Unicast; if it is 1, it is multicast.
Broadcast frames always have 1 as the second bit.
A Unicast frame is addressed to a single network device. This means that
the frame is to be read only by the device that matches the destination
address. All other devices in the collision domain will receive a copy of the
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frame but will discard it because it does not match their destination
address. The address used is the MAC address or hardware address of the
network device.
A multicast frame is addressed to several but not all devices. All devices
that are a part of the specified group may read the frame. A multicast
address is a deviation from the normal hardware address. For example, a
group of devices are assigned access to a particular server on the network.
They are the only devices that receive frames announcing the availability
of that server. Any device that does not belong to this group will ignore or
discard these frames.
A broadcast frame is addressed for all network devices to read and process.
A broadcast address is a unique address used only for broadcast frames. It
is not a hardware address. Broadcast frames are transmitted across
bridges and switches; however, routers will stop broadcast frames.
Check Your Understanding
♦ Describe what the LLC layer does.
♦ What do the MAC sublayer protocols specify?
♦ Create a table that compares a DIX frame and an IEEE 802.3
frame.
♦ Compare and contrast unicast, multicast, and broadcast frames.
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Try It Out
Ethernet LAN
As you c omplete this lab, keep a record of the problems you encounter, how
you solve them, notes indicating how you would prevent these problems
from occurring the next time you encounter this situation, and any other
thoughts you feel should be incorporated into your portfolio. This
information is critical to discovering some very simple troubleshooting
techniques.
Recall from the cabling lesson that there are tip and ring wires on cables.
You crimped a straight-through, category 5 cable, with a RJ-45 connector.
Your computer transmits straight through. In order to receive
transmissions, the cable or the device you’re connecting to must be
crossover. That is because the Tx pin/wire on one device must eventually
enter the Rx pin/wire on the end device. Hubs are crossover devices, that
is, the crossover takes place internally. As a result, you use straight
through cables to connect your computer to the hub.
Media dependent interface (MDI) is the IEEE standard for the interface to
unshielded twisted pair (UTP) cable.
In order for two devices to communicate, the transmitter of one device
must connect to the receiver of the other device. The connection is
established through a crossover function, which can be a crossover cable or
a port that implements the crossover function internally.
Ports that implement the crossover function internally are known as MDIX ports, where X refers to the crossover function.
Ethernet single collision domains may be configured in several ways. In
this lab you will configure a single collision domain using a single hub.
Work in groups of three or four. All the members of your team will connect
their computers to the hub and your team will become an Ethernet
segment.
Materials Needed
•
Manual for BayStack 153 10BaseT Hub
•
Power cords for Hub network connectivity
•
Straight through cable you crimped in Unit 1
Part 1: Identify Hardware
1. Obtain the BayStack 153 10BASE-T Hub documentation from your
teacher.
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2. Read Chapter 1: Introduction, Features, and Description, pages 1-1 to
1-4.
3. Obtain the diagram of the BayStack 153 10BASE-T Hub that you
placed in your portfolio during the Connectivity and Internetworking
Devices lesson.
4. Refer to pages 1-5 and 1-6 of the Hub documentation. Label all of the
parts. Keep diagram in your portfolio.
5. Attach the power cord to the back of the hub and power on the hub.
♦ How many host (RJ-45) ports on the hub? What are the
configuration settings available for port 1? How is the configuration
set for port 1?What is the configuration for the other ports? MDI or
MDI-X?What type of port is on the NIC on the back of your
computer? What is the configuration of the NIC card port? MDI or
MDI-X?
Part 2: Connecting to the Hub
1. Use the straight through cable you crimped or obtain another straight
through cable from your teacher. Connect from your NIC to a host port
on the hub.
♦ Why do you need to use a straight through cable?Did the Link LED
turn to green for your connection? Yes or No
2. If the link did not turn to green, contact your teacher.
3. After all team members are connected to the hub, verify that all LEDs
on the LED display on the hub where workstations are connected are
green.
4. PING will be used to verify each connection.
5. Select the Start menu, select Programs, and select MS DOS Prompt. A
window similar to the following is presented on the screen
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6.
7. Press Enter. Four ping frames will be sent to verify connectivity to the
IP address you requested.
♦ Were you successful? Yes or No
8. If you were not successful, check all connections and the status LEDs of
each host port.
♦ Are there any amber LEDs? Yes or No
If the answer is yes, verify the connection to the computer, the cable
quality, the accuracy of the IP address assigned to the computer you
are tying to reach and the accuracy of your PING request.
♦ Did you find the problem? Yes or No
If you cannot resolve your problem, ask the teacher for help.
♦ Can you PING all members of your team? Yes or No
♦ Have you configured one or two collision domains?
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9. Record the IP addresses on the diagram you created for the structured
cabling lesson.
When you have successfully proven connectivity to all team members and
your instructor, you have completed this lab.
Rubric: Suggested Evaluation Criteria and Weightings
Criteria
%
Participation and teamwork
20
Accurately followed directions
25
Thorough and accurate answers to questions
30
Portfolio. Clarity of notes, relevance of potential
solutions for future similar problems
25
TOTAL
Your Score
100
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Stretch Yourself
Troubleshooting Ethernet LANs
Materials Needed
•
BayStack 152 Hub and documentation
•
LAN
Directions: Refer to the documentation that came with the BayStack 152
Hub. Record the answers to the questions in your portfolios for future
troubleshooting recommendations.
Each of the ports has an LED to indicate port status. The LEDs indicate
link, activity, and partitioning status. The port status indicators always
come on when the hub is powered on. In normal operation, after the POST
(power-on self-test) is completed, the LEDs turn off.
Answer the following questions regarding the description of Hub Status
LEDs.
♦ When the Master is green, what does that indicate?When the Con is
green, what does that indicate?
♦ When the AUI is green and blinking, what does that indicate?
♦ When the Runt is amber, what does that indicate?
♦ When the F/A is amber, what does that indicate?
♦ When the L/C is amber, what does that indicate?
♦ When the Other is amber, what does that indicate?
♦ When the Isolate is amber, what does that indicate?
♦ What does the Hub ID tell you?
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Rubric: Suggested Evaluation Criteria and Weightings
Criteria
%
On time delivery of assignment
15
Questions and answers added to portfolio for
future reference.
25
Completeness and accuracy of answers questions
60
TOTAL
Your Score
100
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Network Wizards
Troubleshooting an Ethernet LAN Case Study
A small company has hired you to solve their networking problem. The
wait time for access to email and other services at the company is very
slow, resulting in lowered productivity. The network is an Ethernet LAN,
bus topology (physical and logical), with 55 devices all connected to the
same collision domain. There are three user groups: sales (30 devices),
accounting (5 devices), and marketing (18 devices), each with its own
server.
The company executives know a little bit about LANs and connectivity
devices; however, they do not know whether to purchase a repeater, a
bridge, a hub, or a combination of these devices.
Materials Needed
•
None
Your assignment is to prepare a document with a proposed solution to
their problem. The document must contain the following:
196
•
Explain the shortcomings of bus topology in this case. Suggest an
alternative topology and defend your choice.
•
Provide a computer-generated sketch of the proposed topology.
•
Prepare documentation that explains the purpose of a hub, repeater,
router, bridge, and switch, and relate these devices to their
corresponding OSI layer. Explain which devices will help solve their
problem and tell them why.
•
Prepare a one-page summary of your proposed solution.
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Rubric: Suggested Evaluation Criteria and Weightings
Criteria
%
On time delivery of proposed solution document
20
Thorough explanation of the shortcomings of bus
topology and defense of proposed topology
changes
20
Accurate sketch of proposed topology
20
Complete and accurate explanation of the various
computer devices, their relationship to the OSI
layers, and which ones will help solve the
company’s networking problems
20
Plausibility of the proposed solution
20
TOTAL
Your Score
100
Summary
In this lesson, you learned to do the following:
•
Describe Ethernet topology.
•
Explain how CSMA/CD is used within an Ethernet topology.
•
Compare and contrast two Ethernet frame types.
•
Describe the relationship between Ethernet standards and the OSI
model.
•
Set up an Ethernet LAN and ping to check for connectivity.
•
Troubleshoot an Ethernet problem scenario.
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Review Questions
Name___________________
Lesson 2-3: Ethernet Basics
Part A
1. Which type of transmission do all devices on the shared network hear
and accept?
a. Unicast
b. Multicast
c. Broadcast
d. Baseband
2. Which type of signaling uses the entire bandwidth of a cable for a
single transmission and allows only one signal at a time?
a. Unicast
b. Multicast
c. Broadcast
d. Baseband
3. When all devices have equal access to the network and no one device
has priority over another device, what is this called?
a. Carrier Sense
b. Multiple Access
c. Collision Detection
d. Collision Domain
4. What is the term used to describe the ability of a device to sense
simultaneous transmission attempts and wait a random amount of
time before retransmitting data?
a. Carrier Sense
b. Multiple Access
c. Collision Detection
d. Collision Domain
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5. What is the ability to listen for a jam signal before transmitting data
called?
a. Carrier Sense
b. Multiple Access
c. Collision Detection
d. Collision Domain
6. Ethernet standards include specifications for which of the following?
a. Cabling
b. Frame format
c. Network access conventions
d. All of the above
7. What are the two IEEE Ethernet standards called?
8. What is the name for the Ethernet standards developed by Xerox, Intel,
and Digital Equipment Corporation?
9. What type of topology configuration(s) does Ethernet employ?
10. List five reasons for the popularity of Ethernet LAN topology.
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Part B
Matching: Match the part of the frame with its definition.
200
1. ___ Preamble
A
One byte code in the LLC field used
to identify the protocol that will
encapsulate the data field
2. ____ Start of Frame
B
Hardware address of the
destination device
3. ___ Destination Address
C
Actual information being
transmitted
4. ___ Source Address
D
Specifies the protocol used for
sending the frame
5. ___ Type Field
E
Specifies the length of the data
within the frame
6. ___ Length Field
F
Type of frame check that detects
errors that occur in the frame
during transmission
7. ___ Pad
G
Added to the data field of IEEE
802.3 when the data is less than 46
bytes
8. ___ Data
H
Establishes synchronization and
transceiver conditions
9. ___ DSAP
I
Field with 10101011 sequence
separate
10. __ CRC
J
Hardware address of the sending
device
ST0025803A
Internetworking Fundamentals
Unit 2: LAN Configurations
Part C
♦ Name the two data link sublayers.
♦ Which sublayer of the OSI do the IEEE 802.2 standards control?
♦ Which sublayer of the OSI do the IEEE 802.3 standards control?
♦ What do the MAC sublayer protocols specify?
♦ Explain how the data link and physical layers are involved in the
creation and transmission of frames.
Scoring
Rubric: Suggested Evaluation Criteria and Weightings
Criteria
%
Part A: Describe Ethernet topology. Explain
how CSMA/CD is used within an Ethernet
topology
30
Part B: Compare and contrast two Ethernet
frame types
40
Part C: Describe the relationship between
Ethernet standards and the OSI model
30
TOTAL
100
Try It Out: Set up an Ethernet LAN and ping
to check for connectivity.
100
Stretch Yourself: Troubleshoot Ethernet
LANs
100
Network Wizards: Troubleshoot possible
Ethernet problems
100
FINAL TOTAL
400
ST0025803A
Your Score
201
Lesson 2-3: Ethernet Basics
Resources
Aschermann, Robert (1998). MCSE Networking Essentials for Dummies.
IDG Books Worldwide, Inc. Forest City, California.
Baker, R. (1996). Data Communications Home Page. Available:
www.georcoll.on.ca/staff/rbaker /intro.sht [1999, May 13].
Bert Glen (1998). MCSE Networking Essentials: Next Generation
Training Second Edition. New Riders Publishing. Indianapolis Indiana.
Chellis, James; Perkins, Charles; & Strebe Matthew (1997). MCSE
Networking Essentials Study Guide. Sybex Inc. Alameda California
CMP Media, Inc. (1999). FDDI fundamentals. In Data Communications
Tech Tutorials [Online]. Available:
www.data.com/Tutorials/FDDI_Fundamentals [1999, April 20].
Computer and Information Science, Ohio State University (No date). Data
Communications Cabling FAQ. [Online].Available: www.cis.ohiostate.edu/hypertext/faq/usenet/LANs/cabling-faq/faq.html [1999, May 13].
Derfler, Jr., Frank J., & Freed, L. (1998). How Networks Work, Fourth
Edition. Macmillan Computer Publishing/Que Corporation. Indianapolis,
Indiana.
Hayden, Matt. (1998). Sam's Teach Yourself Networking in 24 Hours.
Sam's Publishing, Indianapolis, Indiana.
Microsoft Corporation (1998). Dictionary of Computer Terms, Microsoft
Press, Redmond, Washington.
Nortel Networks (1998). Internetworking Fundamentals: Student Guide
Bay Networks Inc. Billerica, Massachusetts.
Palmer , Michael J. (1998) Hands-On Networking Essentials with
Projects, Course Technology, Inc. Cambridge, Massachusetts.
Spurgeon, Charles E. (1997). Practical Networking With Ethernet.
International Thomson Computer Press, Boston, Massachusetts.
202
ST0025803A
Internetworking Fundamentals
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