|
|
5.2 | |
LAN Switches | |
| 5.2.1 | |
Switched LANs, access layer overview |
The construction of a LAN that satisfies the needs of both medium and
large-sized organizations is more likely to be successful if a
hierarchical design model is used. The use of a hierarchical design model will make
it easier to make changes to the network as the organization grows. The
hierarchical design model includes the following three layers:
This hierarchical model applies to any network design. It is important to realize that these three layers may exist in clear and distinct physical entities. However, this is not a requirement. These layers are defined to aid in successful network design and to represent functionality that must exist in a network. The access layer is the entry point for user workstations and servers to the network. In a campus LAN the device used at the access layer can be a switch or a hub. If a hub is used, bandwidth is shared. If a switch is used, then
bandwidth is dedicated. If a workstation or server is directly connected
to a switch port, then the full bandwidth of the connection to the
switch is available to the connected computer. If a hub is connected to
a switch port, bandwidth is shared between all devices connected to the
hub. Access layer functions also include MAC layer filtering and
microsegmentation. MAC layer filtering allows switches to direct frames
only to the switch port that is connected to the destination device. The
switch creates small Layer 2 segments called microsegments. The
collision domain can be as small as two devices. Layer 2 switches are
used in the access layer.
|
Web Links