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| 2.1 |  | VLAN Basics |
| 2.1.2 |  | Motivation for VLANs |

In a legacy network, administrators assign users to networks based on geography. The administrator attaches the user's workstation to the nearest network cable. If the user belongs to the engineering department and sits next to someone from the accounting department, they both belong to the same network because they attach to the same segment. Topologies such as this create interesting network issues and highlight some of the reasons for using VLANs. VLANs help to resolve many of the problems associated with legacy network designs.

With VLANs, network managers can logically group networks that span all major topologies. This includes high-speed technologies such as:

- Asynchronous Transfer Mode (ATM)
- Fiber Distributed Data Interface (FDDI)
- Fast Ethernet
- Gigabit Ethernet
- 10-Gigabit Ethernet

By creating VLANs, system and network administrators can control traffic patterns, react quickly to relocations, and keep up with constant changes in the network due to moving requirements and node relocation. VLANs provide the flexibility to carry out these actions. The network administrator simply changes the VLAN member list in the switch configuration. The administrator can add, remove, or move devices or make other changes to the network configuration using software. In addition to simplified administration, VLANs are also implemented for their increased security and their ability to contain broadcasts.