Networking devices
This page will introduce some important networking devices.
Equipment that connects directly to a network segment is referred to as a device. These devices are broken up into two classifications. The first classification is end-user devices. End-user devices include computers, printers, scanners, and other devices that provide services directly to the user. The second classification is network devices. Network devices include all the devices that connect the end-user devices together to allow them to communicate.
End-user devices that provide users with a connection to the network are also referred to as hosts. These devices allow users to share, create, and obtain information. The host devices can exist without a network, but without the network the host capabilities are greatly reduced. NICs are used to physically connect host devices to the network media. They use this connection to send e-mails, print reports, scan pictures, or access databases.
A NIC is a printed circuit board that fits into the expansion slot of a bus on a computer motherboard. It can also be a peripheral device. NICs are sometimes called network adapters. Laptop or notebook computer NICs are usually the size of a PCMCIA card. Each NIC is identified by a unique code called a Media Access Control (MAC) address. This address is used to control data communication for the host on the network. More about the MAC address will be covered later. As the name implies, the NIC controls host access to the network.
There are no standardized symbols for end-user devices in the networking industry. They appear similar to the real devices to allow for quick recognition.
Network devices are used to extend cable connections, concentrate connections, convert data formats, and manage data transfers. Examples of devices that perform these functions are repeaters, hubs, bridges, switches, and routers. All of the network devices mentioned here are covered in depth later in the course. For now, a brief overview of networking devices will be provided.
A repeater is a network device used to regenerate a signal. Repeaters regenerate analog or digital signals that are distorted by transmission loss due to attenuation. A repeater does not make intelligent decision concerning forwarding packets like a router.
Hubs concentrate connections. In other words, they take a group of hosts and allow the network to see them as a single unit. This is done passively, without any other effect on the data transmission. Active hubs concentrate hosts and also regenerate signals.
Bridges convert network data formats and perform basic data transmission management. Bridges provide connections between LANs. They also check data to determine if it should cross the bridge. This makes each part of the network more efficient.
Workgroup switches add more intelligence to data transfer management. They can determine if data should remain on a LAN and transfer data only to the connection that needs it. Another difference between a bridge and switch is that a switch does not convert data transmission formats.
Routers have all the capabilities listed above. Routers can regenerate signals, concentrate multiple connections, convert data transmission formats, and manage data transfers. They can also connect to a WAN, which allows them to connect LANs that are separated by great distances. None of the other devices can provide this type of connection.