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2.1 | |
Networking Terminology | |
| 2.1.3 | |
Networking devices |
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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.
There are no standardized symbols for
end-user devices in the networking industry.
Network devices provide transport for
the data that needs to be transferred between end-user devices.
A repeater is a network device used to
regenerate a signal. Repeaters regenerate analog or digital signals
distorted by transmission loss due to attenuation. A repeater does not
perform intelligent routing like a bridge or 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 not only concentrate hosts, but they also regenerate signals. Bridges convert network transmission
data formats as well as perform basic data transmission management.
Workgroup switches add more
intelligence to data transfer management.
Routers have all the capabilities
listed above.
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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. Host devices are physically
connected to the network media using a network interface card (NIC).
They use this connection to perform the tasks of sending e-mails,
printing reports, scanning pictures, or accessing databases.
A NIC is a printed circuit board that fits into the expansion slot of
a bus on a computer motherboard, or it can be a peripheral device. It
is also called a network adapter. Laptop or notebook computer NICs are
usually the size of a PCMCIA card.
Each individual NIC carries 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 medium. 
They appear similar to the real devices to allow for quick
recognition. 
Network devices provide extension of cable connections, concentration
of connections, conversion of data formats, and management of 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.
Bridges, as the name implies, provide connections between LANs. Not
only do bridges connect LANs, but they also perform a check on the
data to determine whether it should cross the bridge or not. This
makes each part of the network more efficient. 
Not only can they determine whether data should remain on a LAN or
not, but they can transfer the data only to the connection that needs
that data. Another difference between a bridge and switch is that a
switch does not convert data transmission formats. 
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.
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