Table of Contents for
Packet Tracer Network Simulator

Version ebook / Retour

Cover image for bash Cookbook, 2nd Edition Packet Tracer Network Simulator by Jesin A Published by Packt Publishing, 2014
  1. Cover
  2. Table of Contents
  3. Packet Tracer Network Simulator
  4. Packet Tracer Network Simulator
  5. Credits
  6. About the Author
  7. About the Reviewers
  8. www.PacktPub.com
  9. Preface
  10. Who this book is for
  11. Conventions
  12. Reader feedback
  13. Customer support
  14. 1. Getting Started with Packet Tracer
  15. Installing Packet Tracer
  16. Interface overview
  17. Creating a simple topology
  18. Summary
  19. 2. Network Devices
  20. Customizing devices with modules
  21. Emulating WAN
  22. Accessing the CLI
  23. Summary
  24. 3. Generic IP End Devices
  25. Servers
  26. Other end devices
  27. Configuring end devices
  28. Summary
  29. 4. Creating a Network Topology
  30. Testing connectivity with PDUs
  31. Using the simulation mode
  32. Clustering a topology
  33. Summary
  34. 5. Navigating and Modifying the Physical Workspace
  35. Moving devices physically
  36. Managing cables and distances
  37. Customizing icons and backgrounds
  38. Summary
  39. 6. Configuring Routing with the CLI
  40. Dynamic routing protocols
  41. The Routing table
  42. Load sharing
  43. Summary
  44. 7. Border Gateway Protocol (BGP)
  45. BGP versus dynamic routing protocols
  46. Configuring BGP in Packet Tracer
  47. Summary
  48. 8. IPv6 on Packet Tracer
  49. IPv6 static and dynamic routing
  50. Using both IPv4 and IPv6
  51. Summary
  52. 9. Setting Up a Wireless Network
  53. Wireless networks and physical workspaces
  54. Summary
  55. 10. Configuring VLANs and Trunks
  56. InterVLAN routing with routers and layer 3 switches
  57. Switch-to-switch trunk links
  58. Analyzing broadcasts in the simulation mode
  59. Summary
  60. 11. Creating Packet Tracer Assessments
  61. The initial network
  62. The answer network
  63. Testing the activity
  64. Summary
  65. Index

Chapter 10. Configuring VLANs and Trunks

A switch breaks up collision domains and is a single broadcast domain. So how about breaking the single broadcast domains into multiple ones? VLAN (Virtual LAN) makes this possible and on a single switch we can have multiple broadcast domains. But once you create multiple VLANs on a switch, it becomes tedious to replicate the same configuration on all the other switches. This is where VTP (VLAN Trunking Protocol) comes in. So we have multiple switches with different VLANs and VTP, making management easier. But how do we make a device in one VLAN communicate with a device in another VLAN? We'll cover this in InterVLAN routing.

Creating VLANs and VTP domains

VLAN is a technology used to partition a single layer 2 network into multiple broadcast domains. This is done to restrict communication between devices that share the same broadcast medium. However, these devices can communicate with one another through a layer 3 device, such as a router. This is similar to connecting devices to different switches and then connecting them all to a router to separate broadcast traffic.

As more and more VLANs are created, it becomes tedious to replicate the configuration across all switches, which was why VTP was created.

We'll first learn about creating VLAN and assigning ports to it. VLAN 1 is created by default on all switches, and all ports reside in it. This VLAN is called the management VLAN.

To create a VLAN, use the following command:

Sw1(config)#vlan 2

The VLAN ID can be between 1 and 1001. The IDs 1002, 1003, 1004, and 1005 are reserved. Once this command has been entered, you are taken to the VLAN subconfiguration mode. This is the place where we can assign a name to the VLAN.

Sw1(config-vlan)#name finance

Assigning a name to a VLAN is optional; by default, the name is VLAN0002. Next, we will assign a few ports to this VLAN. To assign many ports to a single VLAN, the range command can be used, which then selects multiple interfaces.

Sw1(config)#interface range f0/10-20

To assign these ports to VLAN 2, use the following command:

Sw1(config-if-range)#switchport access vlan 2

Let's verify if the ports were indeed assigned to the correct VLAN.

Sw1#show vlan
Creating VLANs and VTP domains

Note that in the above example, some of the output has been omitted for brevity.

We will now create a topology with three switches to demonstrate VTP. VTP has three modes: server, client, and transparent.

  • Server: This is the default mode of VTP; in this mode, switches are allowed to modify their VLANs and send VTP advertisements.
  • Client: In this mode, switches listen for VTP advertisements from other server switches. Client switches aren't allowed to modify their VLAN database locally.
  • Transparent: This mode works independent of other switches. In this mode, the switch only forwards the VTP advertisements it receives and does not generate any, neither does it modify its own VLANs based on the VTP advertisements.

The following topology will be used for demonstration:

Creating VLANs and VTP domains
  1. In the first switch (VTP-Server), we will have four VLANs with different names. Then, we will set all the switch-switch ports to trunking.
    VTP-Server(config)#interface Fa0/1
VTP-Server(config-if)#switchport mode trunk
VTP-Transparent(config)#interface range Fa0/1-2
VTP-Transparent(config-if-range)#switchport mode trunk
VTP-Client(config)#interface Fa0/1
VTP-Client(config-if)#switchport mode trunk
  2. Since VTP is already in server mode, we will just change the VTP domain name and set a password.
    VTP-Server(config)#vtp domain My-Office
Changing VTP domain name from NULL to My-Office
VTP-Server(config)#vtp password s3cRet
Setting device VLAN database password to s3cRet
  3. Move on to the second switch (VTP-Transparent) and make it transparent.
    VTP-Transparent(config)#vtp mode transparent
  4. The final task is to move the third switch (VTP-Client) to client mode.
    VTP-Client(config)#vtp mode client
  5. You do not have to change the domain of this switch, as changing it to client will make it pick up the domain name from the server. However, it is necessary to set the VTP password.
    VTP-Client(config)#vtp password s3cRet

The configuration is done; now, use the show vlan command on the VTP-Client switch to see the new VLANs. This example is only to demonstrate VTP. This topology won't allow normal communication between VTP-Server and VTP-Client, as the switch in the middle (VTP-Transparent) doesn't have any of the VLANs we configured.