ECE1001: Circuit and Packet Switching Technologies

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ECE1001 Circuit and Packet Switching Technologies

• Prof. Taek Mu Kwon
• Department of Electrical and Computer
• Engineering

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ECE 4321 Computer Networks

• ECE Technical Elective Course
• 3 Credits
• Network Lab (MWAH 60)
• Network Programming Projects
• Written Exams
• Course Objective On completion of this course
  students are expected to learn and understand
  characteristics of network transmission media,
  OSI model, TCP/IP, data link protocols, routing
  algorithms, various LAN technologies, WAN
  technologies, and network programming.

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Outline

• Introduction
• Circuit switching
• Packet switching

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Telecommunication?

• Telephone
• Mail

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Two Switching Technologies

• circuit switching
• packet switching

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Circuit Switching

• Has three phases
• Circuit establishment
• Data transfer
• Circuit disconnect
• Once connected, the channel is dedicated for the
  duration of the connection
• no header information (overhead) is required

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Circuit Establishment
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Public Circuit Switched Network
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Circuit Switch Elements
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Space Division Switch
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3 Stage Space Division Switch
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Multiplexing

• multiple links on 1 physical line
• common on long-haul, high capacity, links
• have FDM, TDM, STDM alternatives

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Time Division Switching

• modern digital systems use intelligent control of
  space time division elements
• use digital time division techniques to set up
  and maintain virtual circuits
• partition low speed bit stream into pieces that
  share higher speed stream
• individual pieces manipulated by control logic to
  flow from input to output

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Softswitch
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Traditional Circuit Switching
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Switched Network
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Packet Switching

• circuit switching was designed for voice
• packet switching was designed for data
• transmitted in small packets
• packets contains user data and control info
• user data may be part of a larger message
• control info includes routing (addressing) info
• Store and forward packets are received, stored
  briefly (buffered) and past on to the next node

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Packet Switching
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Advantages

• line efficiency
• single link shared by many packets over time
• packets queued and transmitted as fast as
  possible
• data rate conversion
• stations connects to local node at own speed
• nodes buffer data if required to equalize rates
• packets accepted even when network is busy
• priorities can be used

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Switching Techniques

• station breaks long message into packets
• packets sent one at a time to the network
• packets can be handled in two ways
• datagram
• virtual circuit

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DatagramDiagram
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VirtualCircuitDiagram
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Virtual Circuits v Datagram

• virtual circuits
• network can provide sequencing and error control
• packets are forwarded more quickly
• less reliable
• datagram
• no call setup phase
• more flexible
• more reliable

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Packet Size
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Event Timing
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TCP/IP Protocol Suite
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Todays Network
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Integrated Digital Service Revolution (2000 - )

• No boundary between public and private networks
  (security through virtual private network)
• Single mode of transmission for data/voice/video
  high speed multimedia
• No difference between wired and wireless

Multipurpose global network that can be accessed
any time, anywhere