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| 4.1 |  | Methods of Inter-VLAN Routing |
| 4.1.2 |  | Comparison of Layer 2 and Layer 3 operations in the core |

The core is a crucial component of every network. A failure of a core device or link can isolate large sections of a network from one another. For this reason both core links and devices should be designed with adequate redundancy.

In a LAN environment it is possible to implement the core as a switched or routed layer. Although both methods provide redundancy they differ significantly in operation.

The Layer 2 or switched core manages its redundant links using the Spanning-Tree Protocol. This means that some links are not used because one or more ports will be in a Blocking state. Not only does this underutilize the available bandwidth, it also often results in inefficient traffic paths.

The Layer 3, or routed, core manages its redundant links using a routing protocol. The routing protocol has the ability to select the optimal path for traffic and can make use of redundant links through load balancing. Furthermore, implementing the core using Layer 3 allows more flexibility and control over packet flows, permitting additional benefits such as Quality of Service (QoS) to be implemented.