Physical Address, Logical address, Multiplexing

1. L E C T U R E R : M . F A R H A N
Data Communication and Networks

2. Physical address
 In computing, physical address refers to a memory
address or the location of a memory cell in the main
memory.
 It is used by both hardware and software for
accessing data.
 Software, however, does not use physical addresses
directly; instead, it accesses memory using a virtual
address.

3. Con
 A hardware component known as the memory
management unit (MMU) is responsible for
translating a virtual address to a physical address.
 In networking, physical address refers to a
computer's MAC address, which is a unique
identifier associated with a network adapter that is
used for identifying a computer in a network.

4. Con…
 Physical address, which is also called the MAC
address (for Media Access Control) has two parts,
each 3 bytes long.
 The first 3 bytes identify the company that made the
NIC (Network Interface Card). The second 3 bytes
are the serial number of the NIC itself.

5. Logical address
 An address generated by the CPU is a logical address
whereas address actually available on memory unit is
a physical address. Logical address is also known a
Virtual address.
 Computer can have several logical addresses at the
same time, which are use to bring messages to one
physical address.
 .

6. Con..
 Your mailing address, telephone number and home
e-mail address all work to bring messages to you
when you're in your house. They are simply used for
different types of messages different networks, so to
speak

7. Ports
 The TCP layer requires what is called a port number to be
assigned to each message. This way it can determine the
type of service being provided.
 These ports are merely reference numbers used to define
a service. For instance, port 23 is used for telnet services,
and HTTP uses port 80 for providing web browsing
service.
 There is a group called the IANA (Internet Assigned
Numbers Authority) that controls the assigning of ports
for specific services.

8. Addresses
 Addresses are used to locate computers.
 It works almost like a house address. There is a
numbering system to help the mailman locate the
proper house to deliver customer's mail.
 Without an IP numbering system, it would not be
possible to determine where network data packets
should go.

9. Multiplexing
 Multiplexing is the process in which multiple Data
Streams, coming from different Sources, are
combined and Transmitted over a Single Data
Channel or Data Stream.
 In Electronic Communications, the two basic forms
of Multiplexing are Time Division Multiplexing
(TDM) and Frequency Division Multiplexing (FDM).

10. Con..
 Multiplexing is done by an equipment called
Multiplexer.
 It is placed at the Transmitting End of the
communication link. At the Receiving End, the
Composite Signal is separated by an equipment
called Demultiplexer.

11. Demultiplexer
 Demultiplexer performs the reverse process of
Multiplexing and routes the separated signals to
their corresponding Receivers or Destinations.

12. Time Division Multiplexing
 Transmission Time on a Single Channel is divided
into non-overlapped Time Slots.
 Data Streams from different Sources are divided into
Units with same size and interleaved successively
into the Time Slots.

13. Con..
 Time Division Multiplexing interleaves small Units
of each Data Stream into the corresponding Time
Slots.
 It Transmits the Data Streams from three Signal
Sources (Red, Green and Blue) simultaneously by
combining them into a Single Data Stream.

14. Con..

15. Frequency Division Multiplexing
 Data Streams are carried simultaneously on the same
Transmission medium by allocating to each of them
a different Frequency Band within the Bandwidth of
the Single Channel.

16. GUIDED TRANSMISSION MEDIA
 Transmission Media
 Guided Media
 Types of Guided Media
 Twisted Pair cable
 Coaxial Cables
 Optical Fiber

17. Transmission Media
 Sending of data from one device to another is called
transmission of data
 Medium used to transmit the data is called Media
 Transmission of data through Medium is called
Transmission Media
Transmission
Media
Guided Unguided

18. Guided (Wired)
 Guided transmission media means the data
signals are guided along the path like cabling
system . They don't have any other way to go,
they have to pass through the given cable or
wire.

19. Types Of Guided Media

20. Twisted Pair
 A twisted pair consists of two insulated copper wires arranged in a
regular spiral pattern.
 Twisted pair may be used to transmit both analog and digital
transmission.
 Twisted pair is limited in distance, bandwidth, and data rate.
 The attenuation for twisted pair is a very strong function of frequency

21. Twisted Pair Types
 Unshielded Twisted Pair (UTP)
 ordinary telephone wire
 cheapest
 easiest to install
 suffers from external interference

22. Con..
 Shielded Twisted Pair (STP)
 Metal protected that reduces interference
 more expensive
 easiest to install
 harder to handle (thick, heavy)

23. Coaxial Cable
 Coaxial cable consist the followings layers in its
construction
 The copper conductor
 Insulation layer of plastic foam
 Second conductor or shield of wire mesh tube or metallic foil
 Outer jacket of tough plastic

24. Con…
 Coaxial cable can be used over longer distances and support
more stations on a shared line than twisted pair.
 Coaxial cable is used in a wide variety of applications.

25. Fiber Optics
 Fiber optic cable is known as most sophisticated cables used in long
distance network connection.
 Through this cable data transmission is done through « Light ray
signal transmission» rather than electrical signal transmission.
 It has inner core of glass that conducts light. This inner core is
surrounded by cladding.
 Cladding is nothing but layer of glass material that reflects light back
into the core.
 Each fiber is then surrounded by plastic sheath