One of the main reasons that network administrators buy switches is to help control bandwidth problems by creating multiple collision or bandwidth domains, but they can also help contain broadcasts by implementing VLANs.
However, VLANs offer a network administrator many more advantages than just these.
In the simplest terms, a VLAN is a broadcast domain.
In a bridged network, all devices are in the same broadcast domain.
Here are some examples: Broadcasts are a normal occurrence in LAN-based protocols such as IP, IPX, and Apple Talk.
In many cases, these broadcasts help users to find and use services.
It’s a common discussion about when Cisco VTP protocol is actually forwarded through Cisco switches and when it’s isn’t.
I’ve always gotten it somewhat confused and when I stumbled across some old notes on the topic I had an ah-hah moment.However, each broadcast domain is typically considered to be a separate subnet.To go between subnets, a Layer 3 component, such as a router, is still required.Note that VTP was especially useful when first introduced since configuring VLAN over Token Ring and FDDI interfaces was complex, and it took many years for network administrators to understand VLAN configuration.Importantly, VTP was useful to help stabilise Spanning Tree in the early days by ensuring consistentcy, especially in large networks (well, they were large in 1999 anyway….).The only configuration that DOES NOT pass VTP packets is a switch configured in VTPv1 Transparent Mode and VTPv3 in off mode. VTPv3 has four modes: server, client, transparent and off.