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| 1.1 |  | Overview of a Campus Network |
| 1.1.1 |  | Traditional campus networks |

In the early days of networking, primarily research universities and the military experimented with computer networks. The term campus network derives from networks built on university campuses. Today, the term is used more broadly to include networks that span corporate "campuses". Campus size is an important factor in network design. A large campus has several or many co-located buildings, a medium campus is one or several co-located buildings, while a small campus has one building.

Historically, campus networks consisted of a single LAN to which new users were added simply by connecting anywhere on the LAN. Because of distance limitations of the networking media, campus networks usually were confined to a building or several buildings in close proximity to each other, see Figure . The LAN was a physical network that connected the devices. In the case of Ethernet, all the devices shared the available, half-duplex, 10-megabit-per-second (Mbps) network. Because of the carrier sense multiple access collision detect (CSMA/CD) access method used by Ethernet, the whole LAN was considered a single collision domain.

Few design considerations were needed to provide user access to the network backbone. Because of the inherent limitations of Ethernet, physically adjacent users were sometimes connected to a single access device to minimize the number of taps into the backbone. Although hubs met this requirement and became standard devices for multiple network access, increased user demand quickly slowed the performance of the network.