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Chapter. Packet and Circuit Switching. Chapter Objectives. Explain the concept of packet switching Give sample application areas of packet switching Describe circuit switching Compare and contrast packet switching with circuit switching. Chapter Modules. Packet switching

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chapter

Chapter

Packet and Circuit Switching

chapter objectives
Chapter Objectives
  • Explain the concept of packet switching
  • Give sample application areas of packet switching
  • Describe circuit switching
  • Compare and contrast packet switching with circuit switching
chapter modules
Chapter Modules
  • Packet switching
  • Packet switching applications
  • Circuit switching applications
module

Module

Packet Switching

packet switching preview
Packet Switching Preview
  • Explain the concept of a path or a route taken by a packet
  • Study the difference between static and dynamic paths?
  • Relate appropriately the terms packet switching and circuit switching to the terms dynamic and static paths
  • Explore the path taken by a packets in dynamic routing when a packet travels from its origin to its destination
the concept of path in communication
The Concept of Path in Communication
  • A path is a route for data to travel between two nodes in a network
  • Dynamic path
    • In this case, the path often changes from packet to packet
    • Example: Packet Switching
  • Static path
    • Path is initially established and it remains unchanged for the duration of the communication session
    • Example: Circuit Switching
packet switching network
Packet Switching Network

Packet 2

New

York

Los

Angeles

Packet 1

Miami

salient points of packet switching
Salient Points of Packet Switching
  • Path
    • Each packet may take a different path to its destination
    • Best path is heuristically determined at each node
  • Packet switching
    • Path may be switched among packets
    • Hence, the term packet switching
key words
Key Words
  • Packet and circuit switching
  • Dynamic and static paths
module11

Module

Advantages and Disadvantages of Packet Switching

questions
Questions
  • What are the major advantages and disadvantages of packet switching?
  • Could the Internet be called a packet switching network?
  • How does packet switching help in supporting multiple communication sessions?
  • How does a web server support multiple access to its contents? Explain in terms of packets that travel from the web server to their various destinations.
questions continued
Questions (continued)
  • What are the implications of packet switching to the transmission of audio and video in real time?
  • How are the above problems addressed in streaming?
major advantages
Major Advantages
  • Better utilization of the network segments in terms of the usage of the network paths
  • Ability to engage in multiple communication sessions
dynamic assignment of paths
Dynamic Assignment of Paths

New

York

Las

Vegas

Los

Angeles

Miami

support for multiple communication sessions
Support for Multiple Communication Sessions

Session 1

Session 2

New

York

Las

Vegas

Los

Angeles

Miami

disadvantage or a concern
Disadvantage or a Concern
  • Packets may not arrive at their destination in the order in which they were originally transmitted
  • The above possibility exists because of the different paths that are taken by the different packets
order of arrival of packets
Order of Arrival of Packets

Packet 2

New

York

Packet 1

Los

Angeles

Miami

Packet 2 may arrive earlier than Packet 1.

packet assembly
Packet Assembly
  • Packets are assembled to preserve the order of transmission
  • Packets arriving earlier are held in a buffer
  • The order of arrival is critical and in certain cases the order is time sensitive as well
transmission of audio and video in packet switching
Transmission of Audio and Video in Packet Switching
  • Transmission of audio and video are time sensitive
    • Timely arrival of packet is important
  • The process that would ensure the orderly and timely arrival of data packets is known as streaming
  • Streaming also compresses the data to minimize bandwidth requirements thus ensuring that the packets have adequate bandwidth to travel to the destination in the order in which they are supposed to arrive at the destination
buffering in streaming
Buffering in Streaming
  • Streamed audio or video is often buffered to ensure that the audio or video is played continuously
advantages and disadvantages
Advantages And Disadvantages
  • Advantages
    • Efficient use of the network paths
    • Engage in multiple sessions
  • Disadvantages
    • Additional hardware and software resources are required to assemble and route the packets
    • If real-time continuity is stipulated then the data must be subjected to a process known as streaming
special concerns
Special Concerns
  • Audio and video transmission
    • Streaming is used
  • Voice Over IP (VoIP) is designed deploy telephony over the Internet
newer advancements for real time transmission of information
Newer Advancements for Real Time Transmission of Information
  • Faster Internet speed
  • Better technology
    • IPv6
    • Better streaming technologies
questions25
Questions
  • What are the major advantages and disadvantages of packet switching?
  • Could the Internet be called as a packet switching network?
  • How does packet switching help in supporting multiple communication sessions?
  • How does a web server support multiple access to its contents? Explain in terms of packets that travel from the web server to their various destinations on the Internet.
questions continued26
Questions (continued)
  • What are the implications of packet switching to the transmission of audio and video in real time?
    • Relate the above to Voice over IP transmission.
  • How are the above problems addressed in streaming?
module28

MODULE

Packet Switching Applications

questions29
Questions
  • Give a simple example of packet switching application
  • Relate packet switching to multiple session applications on the Internet and give examples of multiple session applications
  • Describe audio transmission challenges on packet-switched networks
questions continued30
Questions (Continued)
  • List the packet switching technologies used in WANs
  • Explain the emergence of the concept of fixed length packets or cells in packet switching networks
    • Name a cell based transmission technology and state its applications
internet an application of packet switching
Internet: An Application of Packet Switching

Packet N1

Internet

Server

New

York

Ramp

Packet M1

Los

Angeles

Miami

Server in Los Angeles supports multiple access to the web

over a packet switched connection.

support for multiple sessions
Support for Multiple Sessions

Session LA

Session HU

Packet 2

New

York

Los

Angeles

Packet 1

Miami

Houston

Packets are displayed on different sessions on the screen.

applications using multiple sessions
Applications Using Multiple-Sessions
  • Sharing
  • Collaboration
  • Multiple access to an Internet server
  • etc.
packet delivery
Packet Delivery

SCREEN

Packets

from

Origin 2:

M1, M2

Packets from

origin 1:

N1, N2

Sharing of Word

document on

Internet under

Microsoft

NetMeeting

audio transmission over packet switching network
Audio Transmission Over Packet Switching Network
  • Relatively high speeds are required on the network
  • Data compression and other techniques are used to ensure continuity know as streaming
  • Sample applications:
    • Audio streaming on the Internet
  • RealAudio is an example of a streaming software
usage of packet switching
Usage of Packet Switching
  • Large computer networks with multiple routers
  • WAN in general
  • Internet in particular
packet switching wan technologies
Packet Switching WAN Technologies
  • Past and Present
    • X.25 Packet Switching
  • Present and Near Future
    • Frame Relay
  • Present and Future
    • Asynchronous Transfer Mode (ATM)
    • ATM is also known as Cell Relay
slide38
ATM
  • Asynchronous Transmission Method (ATM)
  • Based on fixed length packets
  • Switches instead of routers are used to route the information on a network
  • This is the emerging technology in WAN transmission
  • (Include more information on ATM)
recollecting the concept of cell
Recollecting the Concept of Cell

Data

Packet varies in size

Data

Cell is of fixed length

questions40
Questions
  • Give a simple example of packet switching application
  • Relate packet switching to multiple session applications on the Internet and give examples of multiple session applications
  • Describe audio transmission challenges on packet-switched networks
questions continued41
Questions (Continued)
  • List the packet switching technologies used in WANs
  • Explain the emergence of the concept of fixed length packets or cells in packet switching networks
    • Name a cell based transmission technology and state its applications
module 5

MODULE 5

Circuit Switching

questions44
Questions
  • Explain the concepts of circuit switching. How does it function?
  • What are the advantages and disadvantages of circuit switching?
  • Name some applications of circuit switching
  • Compare circuit switching with packet switching
circuit switching network
Circuit Switching Network

Established Circuit

Switch

New

York

Los

Angeles

Circuit established and maintained for

entire duration of communication.

defining characteristics of circuit switching
Defining Characteristics of Circuit Switching
  • Establish (switch) a path (circuit) between two nodes of communication
  • Maintain the circuit for the full duration of communication session
advantages of circuit switching
Advantages of Circuit Switching
  • Continuity assured in the order of transmission
  • Audio can be transmitted without streaming provided adequate bandwidth is available
    • Otherwise streaming is necessary
  • The overhead is low in switching a circuit
disadvantages of circuit switching
Disadvantages of Circuit Switching
  • Inefficient use of the paths that are available within a network
    • This may lead to circuit saturation
  • Users can be locked out of the network
  • Multiple sessions cannot easily be implemented although it is possible to have multiple sessions
circuit saturation
Circuit Saturation

Established Circuit

New

York

Los

Angeles

Miami

Saturation point.

areas of applications
Areas of Applications
  • Voice/Video communications
    • Telephone network
  • Both analog and digital telecommunication lines can be circuit switched
  • ISDN
more on isdn
More on ISDN
  • ISDN has two B channels and one D channel
    • B channel is used for data and D channel is used for monitoring and control of the data transmission
  • B channels are circuit switched and the D channels are packet switched
slide52

Comparison

  • Packet Switching Circuit Switching
  • _______________________________________________
  • Efficient use of network Inefficient use
  • High overhead Low overhead
  • Computer data Audio and video
  • Audio and video
  • transmissions are,
  • however, possible
  • Multiple sessions possible Multiple sessions
  • are easily implemented are possible, however it requires additional hardware and software
questions53
Questions
  • Explain the concepts of circuit switching. How does it function?
  • What are the advantages and disadvantages of circuit switching?
  • Name some applications of circuit switching
  • Compare circuit switching with packet switching