The hub is a central hardware component for many LANs. Hubs operate at the Physical Layer in the OSI model. Hubs contain multiple ports, and can connect to other hubs to expand the network.
Repeaters operate at the Physical Layer of the OSI model. Essentially, repeaters allow smaller LANs to grow into larger LANs by moving transmissions from one network segment to another.
repeater A device that can be used to connect two cables and that boosts the signal before sending it along. (p. 105)
Segment A section of the network that includes the cable and nodes that are connected to a device, such as a repeater, hub, or bridge.
Bridges can be used to connect dissimilar network segments that use different methods of transferring data.
In today’s networks, it is uncommon to find bridges because switches provide “multibridge” capability.
bridge A device used to connect two network segments together. (p. 105)
switch A multiport bridge that allows several segments of a network to communicate with one another. An important function of bridges and switches is to minimize collision of data packets by creating collision domains. Bridges and switches prevent the passing of collisions from one network segment to another.
router A network device used to connect networks of different types and that forwards packets from one network to another, even those separated by great distances. A router determines the best route to use to deliver the data.
Brouters are hybrids that combine the capabilities of bridges and routers. Like bridges, they work at the Data Link Layer to transfer and filter network traffic. Like routers, they also work at the Network Layer to route packets from one network to another. brouter A network hybrid device that combines the capabilities of bridges and routers. Gateways enable dissimilar networks to communicate. Gateways operate at higher levels in the OSI model such as the Application, Presentation, and Session layers. In some cases, they operate at all seven layers. Gateway A dedicated network computer whose job is to convert data packets from one network protocol to another. Enables dissimilar networks to communicate.