Chabot College
ELEC 99.05
Network Topologies & Connections
CISCO NETWORKING ACADEMY
Toplogies and Connections
• Differing physical topologies yield
equivalent ethernet traffic at the
workstation.
• For UTP connections, cable type
depends on the types of devices
connected.
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Bus Topology
Bus
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Extended Star Topology
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Equivalent Ethernets
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Crossover Cable
• Transmit pair “crosses over” to Receive pair.
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Crossover Cable
• Connects NIC to NIC.
transmit pair
transmit pair
(crossover cable)
receive pair
receive pair
• Connects hub to hub.
transmit pair
PWR
10M100M
ACT ACT
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COL COL
SWITCH
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UPLINK
receive pair
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transmit pair
hub
hub
(crossover cable)
PWR
10M100M
ACT ACT
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COL COL
SWITCH
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UPLINK
receive pair
Straight-Through Cable
• Connects NIC to hub.
transmit pair
transmit pair
(straight through cable)
receive pair
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hub
PWR
10M100M
ACT ACT
1 2 3 4 5 6 7 8 9 101112
COL COL
SWITCH
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UPLINK
receive pair
Straight-Through Cable
• When connecting two PCs via a hub,
straight-through cables are used. Where
does the crossover occur?
• In the hub!
transmit pair
transmit pair
PC1 (straight through cable)
hub
PWR
10M100M
ACT ACT
1 2 3 4 5 6 7 8 9 101112
COL COL
SWITCH
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UPLINK
(straight through cable)
receive pair
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PC2
receive pair
Cabling Example
Crossover
Straight - Thru
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Crossover
Straight - Thru
Crossover
Straight - Thru
Hub Feature
• Most hubs have a special “uplink port”
that can be switched from crossover to
straight-through function.
• Usually, the uplink is port 1.
• The uplink allows use of straightthrough cables throughout all
connections.
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Hubs with Uplink
Switchable
Uplink Port
Straight - Thru
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Straight - Thru Straight - Thru
Straight - Thru
Straight - Thru
Quiz
• NIC to NIC - what type cable?
• Crossover
• NIC to hub - what type cable?
• Straight-through
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Quiz
• Hub to hub - what type cable??
• Crossover
• Hub uplink port to hub - what type cable?
• Straight-through
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Quiz
• On most hubs, which port is the hub uplink on?
• Port 1
• Could I attach a workstation NIC to the uplink
port?
• Sure - just use a regular straight-through cable.
If necessary, change the setting on the uplink
port switch!
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Quiz
• How can I tell if the hub’s uplink port switch
is set correctly for the type of cable & device
attached?
• Look for link light!
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