Packet and Circuit Switching - Communication Theory - Lecture Slides, Slides of Data Communication Systems and Computer Networks

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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
• Packet switching applications
• Circuit switching applications

Module

Packet Switching

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

• 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

Los

Angeles

New

York

Packet 2

Packet 1 Miami

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

• Packet and circuit switching
• Dynamic and static paths

End of Module

Module

Advantages and Disadvantages of Packet Switching

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)

• 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

• 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

Los

Angeles

New

York

Miami

Las

Vegas

Support for Multiple Communication Sessions

Los

Angeles

New

York

Miami

Las

Vegas

Session 1

Session 2

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

Los

Angeles

New

York

Packet 2

Packet 1

Miami

Packet 2 may arrive earlier than Packet 1.

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 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

• Streamed audio or video is often buffered to ensure that the audio or video is played continuously

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

• 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

• Faster Internet speed
• Better technology
  • IPv6
  • Better streaming technologies

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.