Repeaters are electronic devices that regenerate signals to extend the range of a local area network (LAN) by connecting two segments. They work at the physical layer of the OSI model by receiving signals, regenerating the original bit pattern, and forwarding the refreshed signal without any filtering or intelligent functions. Repeaters must be placed between segments before the signal becomes too weak or corrupted to extend the physical length and increase the range of a LAN.

1. Sub topic : Repeaters
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2. Recap
In the previous class, you have learnt about
• Internet
• History of Internet
• Advantages of Internet
• Internet today
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3. Objectives
On completion of this period, you would be
able to understand about
• Definition of a Repeater
• Importance of Repeaters
• Function of a Repeater
• Location of a Repeater
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4. Definition of a repeater
• A Repeater is an electronic device that simply
regenerates a signal
• A connecting device between two segments of a
LAN
• It works at physical layer of OSI model
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5. Repeater at physical layer
A B
Application layer Application layer
Presentation layer Presentation layer
Session layer Session layer
Transport layer Transport layer
Network layer Network layer
Data link layer Data link layer
Physical layer Repeater Physical layer
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6. Importance of Repeaters
• It can extend physical length of a LAN
• A repeater can overcome the 10Base5 Ethernet length
restriction
• Repeater can divide the network in to segments
• Range of LAN can be increased
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7. Functions of Repeater
• It receives a signal before it becomes too weak or
corrupted
• Regenerates the original bit pattern
• The repeater forwards the refreshed signal
• It works in the physical layer
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8. Functions of Repeater contd…
• It has no filtering capability
• It is a regenerator, not an amplifier
• It does not perform any intelligent function
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9. Functions of Repeater contd…
Repeater
Regenerated signal Corrupted signal
Right- to- Left Transmission
Repeater
Corrupted signal Regenerated signal
Left-to Right Transmission
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10. Location of a Repeater
• A repeater must be placed so that a signal reaches it
before any noise changes the meaning of any of its bits
• A repeater placed on the line before the legibility of the
signal becomes lost
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11. 5 5
4 4
3 3
2 2
1 1
1 1
Repeater
Segment 1 Segment 2
Fig .3 Repeater connecting two segments of a LAN
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12. Capabilities of a Repeater
• It must be placed between two segments of same LAN
just before any noise changes the meaning of any of its bits
• Just before the signal collapses or change the meaning of bit
pattern
• A repeater placed on the line before the legibility of the signal
becomes lost can still read the signal well enough to determine
the intended voltages and replicate them in their original form
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13. Limitations of a Repeater
• A repeater does not connects two LAN’s
• A repeater cannot connect two networks of different
protocols
• A repeater does not act as an amplifier or as a filter
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14. Summary
In this class, you have learnt about
• Importance of repeaters
• Definition of repeater
• Function of repeater
• Location of a repeater
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15. Quiz
1. A Repeater is a device which connects ?
(a) Two LANs
(b) Two segments of a same LAN
(c) Two WANs
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16. Quiz
2. Repeater is a _____________
(a) Regenerator
(b) An Amplifier
(c) Filter
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17. Frequently Asked Questions
1. Define Repeater
2. Explain the operation of a repeater
3. What are different functions of a repeater
4. What is the importance of a repeater
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