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Switching

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Permanent Virtual Circuit (PVC) Permanent Virtual Circuit (PVC) ... Space- and time-division switches. Packet Switching. Datagram/SVC/PVC approach. Message Switching ... – PowerPoint PPT presentation

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Title: Switching


1
Chapter 14
Switching
2
Figure 14-1
Switched Network
3
Figure 14-2
Switching Methods
4
Figure 14-3
Circuit-Switched Network
5
Figure 14-4
A Circuit Switch
  • n inputs m outputs
  • The number of inputs does not have to match the
    number o outputs.

6
Figure 14-5
A Folded Switch
  • n x n folded switch
  • n lines in full-duplex mode

7
Figure 14-6
Circuit Switching
8
Figure 14-7
Crossbar Switch
  • N inputs m outputs n x m cross-points.
  • Major limitation Number of cross-points.

9
Figure 14-8
Multistage Switch
  • 2 x 2 crossbar switch
  • 15 x 15 crossbar switch 15 x 15 cross-points
  • 5 x 2 crossbar switch 5 x 2 cross-points
  • Number of cross-points
  • - First stage 3 x 5 x 2, Second stage 2 x 2 x
    2, Third stage 3 x 5 x 2

10
Figure 14-9
Switching Path Multi Paths
  • Blocking
  • - The reduction cross-points results in a
    phenomenon called blocking.
  • - As the number of stages increases, possible
    blocking increases.

11
Figure 14-10
TDM with and without a TSI (Time-Slot Interchange)
12
Figure 14-11
Time Slot Interchange
13
Figure 14-12
TDM Bus
14
Figure 14-13
TST (Time-Space-Time) Switch
  • Advantages
  • - Space Switch Instantaneous
  • - Time Switch No cross-points
  • Disadvantages
  • - Space Switch Number of cross-points
  • - Time Switch Delay (Time-Slot Interchange)

15
Figure 14-14
PSTN (Public Switched Telephone Network) Hierarchy
16
Figure 14-15
Touch-Tone Dialing
  • Dual-tone multi-frequency

17
Figure 14-16
Packet Switching Approaches
  • Datagram approach
  • - Each packet is treated independently from all
    others.
  • - Datagram sequence is out of order.
  • - Reorder datagrams in transport layer.
  • Virtual circuit approach
  • - A single route is chosen between sender and
    receiver at the beginning of the session.

18
Figure 14-17
Datagram Approach
19
Figure 14-18
Multiple Channels in Datagram Approach
20
Figure 14-19
Switched Virtual Circuit (SVC)
  • Switched Virtual Circuit (SVC)
  • - A virtual circuit is created whenever it is
    needed and exists only for the duration of the
    specific exchange.

21
Figure 14-20
Permanent Virtual Circuit (PVC)
  • Permanent Virtual Circuit (PVC)
  • - The circuit is dedicated to the specific
    users.
  • - No one else can use it because it is always
    in place.

22
Figure 14-21
Path versus Route
23
Figure 14-22
Dedicated versus Shared
24
Figure 14-23
Message Switching
  • The delays inherent in the process, as well as
    the requirements for large-capacity storage media
    at each node.

25
Summary
  • Circuit Switching
  • Space- and time-division switches
  • Packet Switching
  • Datagram/SVC/PVC approach
  • Message Switching
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