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Configuring VLANs and Trunks

Week #6
Ch3. Wayne Lewis

Routing and Switching CNET 311
Centennial College

Ali Nezhad

Outline
Configure a VLAN Manage VLANs Configure a Trunk Troubleshoot VLANs and Trunks

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Configuring a VLAN

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Configure a Static VLAN Two Methods
Database Config Mode
Being deprecated.

Global Config Mode

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Example

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Display VLANs

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Static VLAN Assignment

A static access port can belong to only one VLAN. To reassign this interface to VLAN1:

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Managing VLANs

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show vlan command

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show interfaces command

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Managing VLANs Example#1

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Managing VLANs Example#2

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Managing VLANs Example#3

VLAN is a virtual interface.
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Other Commands
Counting all VLANs
# show vlan summary

Deleting a VLAN
# no vlan 20 First, assign member ports to another VLAN.

Deleting all non-default VLANs:
# del flash:vlan.dat # reload
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Configuring Trunks

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switchport command
Issue in the interface context Interface goes to a permanent trunking mode. It enters into a DTP negotiation to convert the link into a trunk.
Even if the opposite interface disagrees.
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switchport command

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Removing a Trunk

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Troubleshooting VLANs

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Common Issues
1. 2. 3. 4.

Native VLAN Mismatch
Must be the same on both trunk ends.

Trunk Mode Mismatch
One end ON, the other OFF

VLANs and IP subnets
Incorrect IP addressing info. On PCs, …

Allowed VLANs on Trunks
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CNET 311

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Example#1

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Example#1, Diagnosis & Solution

Fix:
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Example#2

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Example#2, Diagnosis

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Example#2, Solution

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Example#3

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Example#3, Diagnosis

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Example#3, Solution

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Questions?

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