Describing the Campus Infrastructure Module
Layer 2 network issues

Layer 2 switches can significantly improve performance in a CSMA/CD network when used in place of hubs. This is because each switch port represents a single collision domain and the device connected to that port does not have to compete with other devices to access the media. Ideally, every host on a given network segment is connected to its own switch port eliminating all media contention as the switch manages network traffic at Layer 2. An additional benefit of Layer 2 switching is that large broadcast domains can be broken up into smaller segments by assigning switch ports to different VLAN segments.

For all their benefits, some drawbacks still exist in a nonhierarchical-switched network:

  • If switches are not configured with VLANs, very large broadcast domains may be created.
  • If VLANs are created, traffic cannot move between VLANs using only Layer 2 devices.
  • As the Layer 2 network grows, the potential for bridge loops increase. Therefore, the need to use a Spanning Tree Protocol becomes imperative.