Understanding Repeaters, Hubs, Bridges, Switches, and VLANs

Repeaters

Repeaters: are network elements that regenerate the electrical signal that arrives in order to restore it to its original level, thus avoiding problems that might occur due to excessive attenuation. They operate at the physical layer of the OSI model, since they work with signals.

Hubs

A hub has the advantage of simply copying bits from other network segments. It requires no special configuration, being based on the physical layer. It serves no network addresses, protocols, services, etc. It simply repeats the signal from the network at high speed. It does not isolate the traffic problems generated by the network in each of the segments.

Bridges

Bridges: provide some capacity or element of control. They can accept and forward the frames that arrive based on the contents of the frame.

Bridge Phases:

• Store the frame in memory at any port for further analysis.
• Check the frame error control field to ensure its integrity.
• Some bridges are able to modify the frame format.
• The bridge redirects the frame if it determines that the recipient is on a network segment accessible from any network accessible by one of its ports.

Switches

Switch: A device that has functions of OSI Layer 2 and that, therefore, appears as a bridge in its operation.

Switch Phases:

• The switch is always local.
• It connects network segments instead of networks, although at lower levels it is not easy to differentiate one case from another.
• The speed of operation of the switch is greater than that of a bridge, but it introduces greater delay times.
• In a switch, the bandwidth of the network can be shared in an appropriate manner at each network segment or on each node, transparently to users.
• Many business models are stackable and easily scalable.
• Some very high-performance switches are connected in a modular fashion to a very high-speed bus for producing the switching.

Virtual Local Area Networks (VLANs)

A Virtual Local Area Network (VLAN) consists of a logical group of stations physically attached to the ports of one or more switches if the GVRP protocol is enabled, and that are managed in groups.

Main VLAN Features:

• Improved network speed through improved management of communication ports.
• Increased bandwidth by improving allocation needs.
• Increased network security.