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.