All parts of switching are given here.

1. PRESENTATION
on Switching

2. Objectives
 Switching
 Space division switching
 Time division switching
 Two dimensional switching
 Circuit switching
 Packet switching
 Hybrid switching
 Timing
 Network synchronization
 Routing and Traffic control

3. Introduction of Switching
 By consists of a series of interlinked nodes
 Data transfer from source to destination

4. Switching Technologies
 Space Division
 Time Division
 Two dimensional

5. Space-Division Switching
 Each input takes a different physical path in the switch matrix depending on
the output.
 Provide a separate physical connection between inputs and outputs
 Transfer signal from a given input to specific output

6. Crossbar Switch
As digits are dialed, the control element of the switch receives the entire address
before processing it.

7. Crossbar Switch note:
 CROSSBAR arises from the use if crossing horizontal and vertical bars to select
contacts on the cross-point.
 Step-by-Step and Crossbar Switching Systems use electro-mechanical
components for both switching matrix and control elements.

8. Space-Division Switching
(advantages and disadvantages)
Advantage of space-Division Switch
 It is instantaneous
Disadvantages of space division switch
 Limitation of this design is the number of crosspoints required
 With this number of crosspoints is impractical
 Switch is also inefficient

9. Time-Division Switching
 Uses time-division multiplexing
 Most popular technology time-slot interchange(TSI)
Time-Slot Interchange
 Connecting four input lines to
four output lines
 Each input line wants to send
data to an output line according
to the following pattern.

10. Time-Division Switching(cont.)
 The size of each location is the same as the single time slot
 Combines a TDM multiplexer, a TDM demultiplexer and a TSI
 TSI consisting of RAM with several memory location
Advantage of Time-division switching
 Needs no crosspoints
Disadvantage of Time-division switching
 Processing each connection creates delays.

11. Two Dimensional Switching
 Combination of space division switching and time division
switching.
 Achieved both time slot interchange and sample switching trunks.
 Multistage switches of this sort can be designed as time-space-
time (TST) switch and space-time-space (STS) switch.
 Main task is to interconnect an incoming time slot and an
outgoing time slot.
 The unit responsible for this function is group switch.

12. Configuration of TST
Combination of both Space
and time division , we find
Time and Space division
The advantage of space-
division switching is that it
is instantaneous
The advantage of time-
division switching is that
it needs no cross points.

13. Time-space-time switch combination
 consists of two time stages and one space stage.
 12 inputs and 12 outputs.
 Instead of one time-division switch, it divides the inputs into three groups and directs
them to three timeslot interchanges
 The last stage is a mirror image of
the first stage.
 The middle stage is a space-division
switch (crossbar).
Fig: Time-space-time switch or two dimensional switch

14. Two Dimensional Switching
features
 Low blocking probability
 Good implementation advantages
 More cost effective

15. Circuit Switched Networks
 A set of switches connect by physical links
 Only one channel dedicated on each link
 By dividing n channel by using FDM or TDM
 Dedicated route is established between
the source and the destination
 The entire message is transferred
through it.
Fig : Circuit Switching

16. Circuit Switched Network’s Basic
Elements
 End-Stations (or Terminals)
 Transmission Media
 Switching Nodes
Phases of a Circuit Switching
 Circuit Establishment
 Data Transfer
 Circuit Disconnect
Figure : Circuit Switched Network

17. Characteristic of a Circuit-Based Switch
 Blocking Switching Node
-occurs when the switching matrix does not allow some input lines to be
connected to output lines.
-used on voice system
 Non-blocking Switching Node
-allows all inputs to be connected to all outputs.
-used for data connections.

18. Advantages and Disadvantages of Circuit Switching
Advantages
 Provides a guaranteed data rate.
 Data is transmitted without any delay
 Suitable for long continuous transmission.
Disadvantages
 Cause of dedicated connection ,it can’t transmit any other data ,even channel is
free.
 Dedicated channels require more bandwidth.
 Establishing a physical link between the two stations is too long.

19. Packet Switched Networks
 A digital network technology that breaks up a message into fixed size packets
for transmission
 Packets of different messages share the communication channel
 When traversing network switches , routers and other network nodes ,
packets are buffered and queued , resulting in variable delay and throughput
depending on the traffic load in the network
 Each packet is then transmitted individually and can even follow different
routers to its destination

20. Pictorial representation of Packet Switched
Networks

21. Switching Technique of Packet Switched
Networks
 Station breaks long message into packets
 Packets sent one at a time to the network
 Packets handled in two ways
-Datagram approach
-Virtual circuit approach

22. Datagram approach
 In a datagram network, each packet is treated independently of all others.
 Packets in this approach are referred to as datagram
 Each packet is separately addressed & treated as independent
 Figure explains the theory datagram transmission clearly.

23. Virtual Circuit approach
 Virtual circuit network is implemented at the data link layer
 A circuit switch network is implemented at physical layer
 Datagram is implemented at network layer
 A virtual network is a cross between a circuit switched network & a
datagram network . It has some characteristics of both.

24. Advantages and disadvantages of Packet
Switching

25. Hybrid Switching
 This switching format is a hybrid of packet and circuit switching and
combines advantages of both.
 Based on synchronous slots
 Hybrid Transfer Mode(HTM)
-QoS data on slots periodically
-BE packets flows through the rest of slots
 Hybrid Switch
- TDM switch + Packet switch

26. Hybrid Switching (cont.)

27. Advantages & Disadvantage of Hybrid
Switching
Advantages :
 Achieves this by taking advantage of the internet and its lower price
points .
 Managed hybrid network can help add bandwidth
 Alleviate the strain on network capacity
Disadvantages :
 Possible long wait to establish a connection during which no data can
be transmitted.
 More expensive than any other switching techniques.
 A dedicated path is required for each connection.

28.  The method used by the data communication system
 The destination recognizes the start of a data communication
 Reliably reads the information sent
Timing

29. 1. Asynchronous Transmission
2. Synchronous Transmission
Types of timing schemes

30.  Send only 1 character at a time
 Character being the alphabet or number or control character
 Preceding each character is a start bit
 Ending each character is 1 or more stop bits
Asynchronous Transmission

31.  Send block of data at a time
 Each block is preceded by a Start Field
 Also have an end field
 Both have a special bit
 The block can contain up to 64,000 bits
Synchronous Transmission

32.  Known as "networks of coupled dynamical systems“
 Allows to coordinate and schedule actions between stations
 Used in Ethernet and Internet protocol
Network Synchronization

33.  Sender/Receiver Synchronization
 Receiver/Receiver Synchronization
Sender/Receiver(SR) synchronization
 A sender presents its time signal as a timestamp message to one
recipients.
 Each receiver takes a timestamp at the arrival of this message.
 The sender and all receivers are synchronize when the steady
condition reached.
Types of network Synchronization

34. Types of network Synchronization (cont.)
Receiver/Receiver(RR) synchronization
• A sender transmits a broadcast message to numerous receivers.
• The recipients timestamp the message upon gathering and exchange this information with
different receivers that have taken the same message.
• Just the receivers are synchronized and the sender stays unsynchronized

35.  The purpose of moving packets across a network from one host to
destination
 Performed by dedicated device called routers
 Each switch has a routing table
Routing

36. Figure 3:Routing table
Routing Table

37.  Destination device address
 Neighbor routers for learning about remote network
 Possible routers to all remote network
 The best route with the shortest path to each remote network
 How the routing information can be verified and maintained
Routing process

38. 1. Static routing
2. Dynamic routing
Static Routing
 Static routing does not involve any change in routing table unless the
network administrator changes or modify them manually.
Dynamic Routing
 Dynamic routing is a superior routing technique.
 It alters the routing information according to the altering network
circumstances by examining the arriving routing update message
Routing Types

39.  The process of managing, controlling or reducing the network traffic
 Particularly internet bandwidth
 Used by the network administrators
 Part of bandwidth management
 Necessary to measure the network traffic to determine the cause of network
congestion
 Necessary for efficient use of datacenter network bandwidth and for
maintaining service level agreements.
Traffic control

40. Any Question?

41. THANKS
to
ALL