Ali Nezhad

Routing and Switching

CNET 311

Centennial CollegeCentennial College

Configuring VLANs and Trunks

Week #6Ch3. Wayne Lewis

2

Ali Nezhad

Routing and SwitchingCNET 311

Outline

� Configure a VLAN

� Manage VLANs

� Configure a Trunk

� Troubleshoot VLANs and Trunks

3

Ali Nezhad

Routing and SwitchingCNET 311

Configuring a VLAN

4

Ali Nezhad

Routing and SwitchingCNET 311

Configure a Static VLAN

� Two Methods

� Database Config Mode

� Being deprecated.

� Global Config Mode

5

Ali Nezhad

Routing and SwitchingCNET 311

Example

6

Ali Nezhad

Routing and SwitchingCNET 311

Display VLANs

7

Ali Nezhad

Routing and SwitchingCNET 311

Static VLAN Assignment

� A static access port can belong to only one VLAN.

� To reassign this interface to VLAN1:

8

Ali Nezhad

Routing and SwitchingCNET 311

Managing VLANs

9

Ali Nezhad

Routing and SwitchingCNET 311

show vlan command

10

Ali Nezhad

Routing and SwitchingCNET 311

show interfaces command

11

Ali Nezhad

Routing and SwitchingCNET 311

Managing VLANs

Example#1

12

Ali Nezhad

Routing and SwitchingCNET 311

Managing VLANs

Example#2

13

Ali Nezhad

Routing and SwitchingCNET 311

Managing VLANs

Example#3

� VLAN is a virtual interface.

14

Ali Nezhad

Routing and SwitchingCNET 311

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

15

Ali Nezhad

Routing and SwitchingCNET 311

Configuring Trunks

16

Ali Nezhad

Routing and SwitchingCNET 311

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.

17

Ali Nezhad

Routing and SwitchingCNET 311

switchport command

18

Ali Nezhad

Routing and SwitchingCNET 311

Removing a Trunk

19

Ali Nezhad

Routing and SwitchingCNET 311

Troubleshooting VLANs

20

Ali Nezhad

Routing and SwitchingCNET 311

Common Issues

1. Native VLAN Mismatch

� Must be the same on both trunk ends.

2. Trunk Mode Mismatch

� One end ON, the other OFF

3. VLANs and IP subnets

� Incorrect IP addressing info. On PCs, …

4. Allowed VLANs on Trunks

21

Ali Nezhad

Routing and SwitchingCNET 311

Example#1

22

Ali Nezhad

Routing and SwitchingCNET 311

Example#1, Diagnosis & Solution

Fix:

23

Ali Nezhad

Routing and SwitchingCNET 311

Example#2

24

Ali Nezhad

Routing and SwitchingCNET 311

Example#2, Diagnosis

25

Ali Nezhad

Routing and SwitchingCNET 311

Example#2, Solution

26

Ali Nezhad

Routing and SwitchingCNET 311

Example#3

27

Ali Nezhad

Routing and SwitchingCNET 311

Example#3, Diagnosis

28

Ali Nezhad

Routing and SwitchingCNET 311

Example#3, Solution

29

Ali Nezhad

Routing and SwitchingCNET 311

Questions?