Section 1.2: The New Campus Network

The problems with collision, bandwidth, and broadcasts, together with the changes in customer network requirements have necessitated a new network campus design. Higher user demands and complex applications force the network designers to think more about traffic patterns instead of solving a typical isolated department issue. Now network administrators need to create a network that makes everyone capable of reaching all network services easily. They therefore need to must pay attention to traffic patterns and how to solve bandwidth issues. This can be accomplished with higher-end routing and switching techniques. Because of the new bandwidth-intensive applications, video and audio to the desktop, as well as more and more work being performed on the Internet, the new campus model must be able to perform:

• Fast Convergence, i.e., when a network change takes place, the network must be able to adapt very quickly to new changes and keep data moving quickly.

• Deterministic paths, i.e., users must be able to gain access to a certain area of the network without fail.

• Deterministic failover, i.e., the network design must have provisions which ensure that the network stays up and running even if a link fails.

• Scalable size and throughput, i.e., the network infrastructure must be able to handle the new increase in traffic as users and new devices are added to the network.

• Centralized applications, i.e., enterprise applications accessed by all users must be available to support all users on the internetwork.

• The new 20/80 rule, i.e., instead of 80 percent of the users' traffic staying on the local network, 80 percent of the traffic will now cross the backbone and only 20 percent will stay on the local network. (The new 20/80 rule is discussed below in Section 1.3.)

• Multiprotocol support, i.e., networks must support multiple protocols, some of which are routed protocols used to send user data through the internetwork, such as IP; and some of which are routing protocols used to send network updates between routers, such as RIP, Enhanced Interior Gateway Routing Protocol (EIGRP), and Open Shortest Path First (OSPF).

• Multicasting, which is sending a broadcast to a defined subnet or group of users who can be placed in multicast groups.