4. • Ethernet hub, active hub, network hub, repeater hub, multiport repeater or hub is
a device for connecting multiple Ethernet devices together and making them act
as a single network segment. It has multipleinput/output (I/O) ports, in which
a signal introduced at the input of any port appears at the output of every port
except the original incoming. A hub works at the physical layer (layer 1) of
the OSI model. Repeater hubs also participate in collision detection, forwarding
a jam signal to all ports if it detects a collision.
• Some hubs may also come with a BNC and/or Attachment Unit Interface (AUI)
connector to allow connection to legacy 10BASE2 or 10BASE5 network segments.
The availability of low-priced network switches has largely rendered hubs
obsolete but they are still seen in 20th century installations and more specialized
applications.
HUB
7. • 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.
Modem
9. • เราเตอร์ (อังกฤษ: router) เป็นอุปกรณ์คอมพิวเตอร์ที่ทาหน้าที่หา
เส้นทางและส่ง(forward)แพ็กเกตข้อมูลระหว่างเครือข่ายคอมพิวเตอร์ไป
ยังเครือข่ายปลายทางที่ต้องการ เราเตอร์ทางานบนเลเยอร์ที่ 3 ตาม
มาตรฐานของ OSI Model
10. • 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.
Router
