3. A common connection point for devices in a network. Hubs are
commonly used to connect segments of a LAN. A hub contains
multiple ports. When a packet arrives at one port, it is copied to the
other ports so that all segments of the LAN can see all packets
5. A modem (modulator-demodulator) is a device
that modulates an analog carrier signal to encode digital
information anddemodulates the signal to decode the
transmitted information. The goal is to produce a signal that
can be transmitted easily and decoded to reproduce the
original digital data. Modems can be used with any means of
transmitting analog signals, from light emitting diodes to radio.
A common type of modem is one that turns the digital data of
a computer into modulated electrical signal for transmission
over telephone lines and demodulated by another modem at the
receiver side to recover the digital data.
8. A router is a device that forwards data packets between computer
networks. This creates an overlay internetwork, as a router is connected
to two or more data lines from different networks. When a data packet
comes in one of the lines, the router reads the address information in
the packet to determine its ultimate destination. Then, using information
in its routing table or routing policy, it directs the packet to the next
network on its journey. Routers perform the "traffic directing" functions
on the Internet. A data packet is typically forwarded from one router to
another through the networks that constitute the internetwork until it
reaches its destination node
