The Collapsed Backbone and the VLAN

The Collapsed Backbone and the VLAN
To understand how a VLAN looks to a switch, it’s helpful to begin by first looking at a traditional
collapsed backbone. Figure 14.2 shows a collapsed backbone created by connecting physical
LANs to a router.
Each network is attached to the router, and each network has its own logical network number.
Each node attached to a particular physical network must match that network number to
be able to communicate on the internetwork. Now let’s look at what a switch accomplishes. Figure
14.3 shows how switches remove the physical boundary.