Chapter 11. Automatically configuring VLANs using the VLAN Trunking Protocol
Now that you’ve set up a trunk between your switches, it’s time to introduce you to another cool feature of IOS that can save you a bit of time when configuring VLANs on your new switches.
In the last chapter, when you were configuring Switch2 you had to manually create VLANs 600 and 700 on it. This wasn’t a big deal because you had to do this on only one switch, but what if you had to add 10 new switches and each switch needed 100 VLANs? Although manually adding VLANs isn’t a difficult process, it doesn’t scale well.
To solve this, Cisco has given us a cool feature called the VLAN Trunking Protocol (VTP). VTP saves you from having to manually create VLANs on each switch in your topology. Instead, you create your VLANs on only one switch, and VTP automatically creates and names those same VLANs on all your other switches, provided they’re connected via trunk links and you’ve configured VTP properly.
Figure 11.1 illustrates what you’ll be building out in this chapter. VTP uses a client/server configuration. The VTP server is the switch where you’ll configure all your VLANs—Switch1 in this case. The VTP process running on Switch1 will send out VTP advertisements across the trunk connected to Switch2. A VTP advertisement is a message that contains a list of VLANs configured on Switch1. Switch2 will receive the advertisements and automatically create the VLANs that exist on Switch1.