Content

| 1.1 |  | Overview of a Campus Network |
| 1.1.6 |  | Evolving campus structure |

Increased user demands and complex applications have forced network designers to focus on the actual traffic patterns in the network. Networks can no longer be divided into subnetworks based only on the number of users. The emergence of enterprise servers that run applications serving all users also have a direct effect on the load across the network. A higher traffic load across the entire network, results in the need for more efficient routing and switching techniques. In the new campus model, traffic patterns dictate the placement of the services required by the end user. To service the local traffic, Layer 2 switches are moving to the edge of the network and into the wiring closets. These switches connect end-user devices and servers into a common workgroup. Services can be separated into three separate categories:

- Local services
- Remote services
- Enterprise services

A local service is one where the entities that provide the service reside on the same subnet, and therefore, the same virtual network as the user. Local services remain in specific areas of the network. Traffic to and from local services is confined to links between the server, the switches, and the end users. Local traffic does not enter the network backbone or pass through a router.

A remote service is an entity that may be geographically close to the end user, but is not on the same subnet or VLAN as the user. Traffic to and from remote services may or may not cross the backbone. Requests for the remote services will have to cross broadcast domain boundaries because these services are remote to the requesting end user. Therefore, switches must connect to Layer 3 devices to allow for access to remote services.

Enterprise services are services common to all users. Examples of enterprise services are e-mail, Internet access, and videoconferencing. Because all users need to access enterprise services, these servers and services exist within a separate subnet placed close to the backbone. Because enterprise services exist outside of the broadcast domain of the end user, Layer 3 devices are required to access these services. The enterprise services may or may not be grouped by Layer 2 switches.

Placing the enterprise servers close to the backbone ensures the same distance from each user. This also means that all traffic going to an enterprise server will indeed cross the network backbone.

| Interactive Media Activity Drag and Drop: Evolving Campus Structure After completing this activity, the students will understand the campus structure.