Chapter Overview
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Ethernet
Token Ring
FDDI
Wireless Networking
1
Ethernet Standards
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Ethernet is the most popular local area
network (LAN) protocol operating at the datalink layer.
There are two sets of Ethernet standards:
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DIX Ethernet
Institute of Electrical and Electronic Engineers
(IEEE) 802.3
2
DIX Ethernet Standards
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DIX Ethernet. Also known as thick Ethernet,
ThickNet, or 10Base5
DIX Ethernet II. Retains 10Base5 and adds
10Base2 (thin Ethernet)
3
IEEE 802.3 Standards
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IEEE 802.3. 10Base5, 10Base2, and 10Base-T
IEEE 802.3u. Fast Ethernet
IEEE 802.3z and IEEE 802.3ab. Gigabit
Ethernet
4
DIX Ethernet/IEEE 802.3
Components
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Physical layer specifications
Frame format
CSMA/CD MAC mechanism
5
Standard 10-Mbps Ethernet
Specifications
Designation
Cable Type
Topology Maximum
Length
10Base5
RG-8 coaxial
Bus
500 meters
10Base2
RG-58 coaxial
Bus
185 meters
10Base-T
Category 3 UTP
Star
100 meters
Fiber Optic InterMultimode fiber
Repeater Link (FOIRL) optic
Star
1,000 meters
10Base-F
Star
500–2,000
meters
Multimode fiber
optic
6
Fast Ethernet (100 Mbps)
Specifications
Designation Cable Type
Topology Maximum
Length
100Base-TX
Category 5 UTP
Star
100 meters
100Base-T4
Category 3 UTP
Star
100 meters
100Base-FX
Multimode fiber
optic
Star
412 meters
7
Gigabit Ethernet (1,000 Mbps)
Specifications
Designation
Cable Type
Topology
Maximum Length
1000Base-T
Category 5 or 5E UTP
Star
100 meters
1000Base-LX
Various multimode fiber
optic
Star
550–5,000 meters
1000Base-SX
Various multimode fiber
optic
Star
220–500 meters
1000Base-LH
Singlemode fiber optic
Star
10 kilometers
1000Base-ZX
Singlemode fiber optic
Star
100 kilometers
1000Base-CX
150-ohm copper
Star
25 meters
8
Coaxial Ethernet Standards
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10Base5 (thick Ethernet)
10Base2 (thin Ethernet)
9
Coaxial Network Characteristics
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Runs at 10 Mbps
Uses the bus topology
Uses mixing segments
10
Mixing Segments
11
UTP Ethernet Standards
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10Base-T
100Base-TX (Fast Ethernet)
100Base-T4 (Fast Ethernet)
1000Base-T (Gigabit Ethernet)
12
UTP Network Characteristics
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Runs at various speeds up to 1,000 Mbps
Uses the star topology
Requires a hub
Uses link segments
13
Link Segments
14
Fiber Optic Ethernet
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Fiber Optic Inter-Repeater Link (FOIRL)
IEEE 802.3 fiber optic standards:
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10Base-FL
10Base-FB
10Base-FP
100Base-FX
Gigabit Ethernet standards
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The 5-4-3 Rule
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A standard network can have no more than
FIVE segments, connected by FOUR
repeaters, of which no more than THREE
segments can be mixing segments.
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A Coaxial 5-4-3 Network
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A UTP 5-4-3 Network
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Fast Ethernet Hub Types
Class
Function
I
Connects different cable segment types
II
Connects identical cable segment types
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Fast Ethernet Cabling Guidelines
Hub
Type
Maximum Maximum
Number
Total Cable
of Hubs
Length (UTP)
Maximum Total
Cable Length
(Fiber Optic)
Class I
1
200 meters
272 meters
Class II 2
205 meters
228 meters
20
The Ethernet Frame Format
21
Protocol Identification
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DIX Ethernet frames use the Ethertype field.
IEEE 802.3 frames use the Logical Link
Control (LLC) and Subnetwork Access
Protocol (SNAP) subheaders.
22
Media Access Control (MAC)
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Is the mechanism that enables multiple
computers to use the same network medium
without conflicting
23
CSMA/CD Phases
Phase
Description
Carrier sense
A computer listens to the network
before transmitting.
Multiple access
When the network is clear, the
computer transmits the packet.
Collision detection
The computer checks for signs of a
collision. If one occurs, it retransmits
the packet.
24
Collisions
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Collisions are also called signal quality errors.
They are normal on Ethernet networks.
The frequency of collisions increases as
network traffic increases.
Late collisions are a sign of a serious
problem.
25
Token Ring Cable Types
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IBM Type 1. Proprietary shielded twisted pair
(STP)
IBM Type 3. Standard Category 5 unshielded
twisted pair (UTP)
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IBM Type 1 Cable
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Token Passing
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A token frame circulates continuously around
the network.
Only the computer holding the token can
transmit data.
The transmitting system is responsible for
removing the data from the ring.
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Token Ring Frame Types
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Data frame
Token frame
Command frame
Abort delimiter frame
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The Data Frame Format
30
The Token Frame Format
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Fiber Distributed Data Interface
(FDDI) Characteristics
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First commercial 100-Mbps fiber optic
protocol
Uses the token passing MAC mechanism
Supports both singlemode and multimode
cable
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FDDI Topologies
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Double ring
Logical ring
Dual ring of trees
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Dual Ring of Trees
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The FDDI Data Frame
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IEEE 802.11 Standards
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IEEE 802.11a. Speeds of 1 to 2 Mbps
IEEE 802.11b. Speeds of 5.5 to 11 Mbps
36
IEEE 802.11 Topologies
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Ad hoc. Wireless computers communicating
with each other
Infrastructure. Wireless computers using an
access point to communicate with a cabled
network
37
CSMA/CA
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Carrier Sense Multiple Access with Collision
Avoidance (CSMA/CA) is a variation of
CSMA/CD.
It uses packet acknowledgment messages
instead of collision detection.
38
Chapter Summary
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Ethernet
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Token Ring
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Uses a logical ring topology
Uses the token passing MAC mechanism
FDDI
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Supports multiple cable types and speeds
Uses the CSMA/CD MAC mechanism to detect collisions
Uses a double ring or star topology
Uses the token passing MAC mechanism
Wireless Networking
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Runs at speeds up to 11 Mbps
Uses the CSMA/CA MAC mechanism
39