Introducing the New Campus Model

Introducing the New Campus Model
The changes in customer network requirements—in combination with the problems with collision,
bandwidth, and broadcasts—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. We can no longer just think
about creating subnets and putting different departments into each subnet. We need to create
a network that makes everyone capable of reaching all network services easily. Server farms,
where all enterprise servers are located in one physical location, really take a toll on the existing
network infrastructure and make the way we used to design networks obsolete. We must pay
attention to traffic patterns and how to solve bandwidth issues. This can be accomplished with
higher end routing and switching techniques.
VLAN 1 VLAN 3
VLAN 2 VLAN 4
E0 E1
Introducing the New Campus Model
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Because of the new bandwidth-intensive applications, video and audio being delivered to the
desktop, as well as more and more work being performed on the Internet, the new campus
model must be able to provide the following:
Fast convergence
When a network change takes place, the network must be able to adapt very
quickly to the change and keep data moving swiftly.
Deterministic paths
Users must be able to gain access to a certain area of the network without fail.
Deterministic failover
The network design must have provisions that make sure the network
stays up and running even if a link fails.
Scalable size and throughput
As users and new devices are added to the network, the network
infrastructure must be able to handle the new increase in traffic.
Centralized applications
Enterprise applications accessed by all users must be available to
support all users on the internetwork.
The new 20/80 rule
Instead of 80 percent of the users’ traffic staying on the local network,
80 percent of the traffic now crosses the backbone and only 20 percent stays on the local network.
Multiprotocol support
Campus networks must support multiple protocols, both routed and
routing protocols. Routed protocols are used to send user data through the internetwork (for
example, IP or IPX). Routing protocols are used to send network updates between routers,
which will in turn update their routing tables. Examples of routing protocols include RIP,
Enhanced Interior Gateway Routing Protocol (EIGRP), and Open Shortest Path First (OSPF).
Multicasting
Multicasting is sending a broadcast to a defined subnet or group of users. Users
can be placed in multicast groups, for example, for videoconferencing.
QoS
We need to be able to prioritize different traffic types.