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CCNA 3 v3.1 Module 8

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CCNA 3 Module 8

Virtual LANS (VLANS)

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Objectives of Module 8

• VLAN concepts

• VLAN configuration

• Troubleshooting VLANs

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Introduction to VLANs

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VLANs

VLANs logically segment switched networks based on an organization's functions, project teams, or applications as opposed to a physical or geographical basis.

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Broadcast Domains

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3 Broadcast Domains, 3 VLANs

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Static VLANs

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Dynamic VLANs

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Port-Centric VLANs

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VLAN Configuration

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Benefits of VLANs

• Easily move workstations on the LAN

• Easily add workstations to the LAN

• Easily change the LAN configuration

• Easily control network traffic

• Improve security

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Communicating Between VLANs

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VLAN Types

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Inter-Switch Link

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Concurrent Transmissions in a Switch

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End-to-End VLANs

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Static VLANs

• Static VLANs work well in networks where the following is true:

Moves are controlled and managed.

There is robust VLAN management software to configure the ports.

It is not desirable to assume the additional overhead required when maintaining end-station MAC addresses and custom filtering tables.

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Verifying VLAN’s

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Saving VLAN Configuration

Back up using the copy running-config tftp command, or you can use the HyperTerminal Capture Text feature to store the configuration settings.

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Deleting VLANs

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VLAN Problem Isolation

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Problem Isolation in Catalyst Networks

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Preventing Broadcast Storms

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Common Problems in Troubleshooting VLANs

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show vlan Command

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Catalyst IOS Keyword Syntax Description

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show spanning-tree Command

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VLAN Troubleshooting Scenarios

A trunk link cannot be established between a switch and a router

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VLAN Troubleshooting Scenarios

VTP is not properly propagating VLAN configuration changes.

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VLAN Troubleshooting Scenarios

Dropped packets and loops