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  • Topic: Circuit switching, Packet switching, Crossbar switch
  • Pages : 3 (415 words )
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  • Published : May 24, 2013
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Digital Switching

EE4367 Telecom. Switching & Transmission

Prof. Murat Torlak

Switching
A switch transfers signals from one input port to an appropriate output. A basic problem is then how to transfer traffic to the correct output port. In the early telephone network, operators closed circuits manually. In modern circuit switches this is done electronically in digital switches. If no circuit is available when a call is made, it will be blocked (rejected). When a call is finished a connection teardown is required to make the circuit available for another user.

EE4367 Telecom. Switching & Transmission

Prof. Murat Torlak

Crossbar Switch
A crossbar switch with N input lines and N output lines contains an N x N array of cross points that connect each input line to one output line. In modern switches, each cross point is a semiconductor gate.

EE4367 Telecom. Switching & Transmission

Prof. Murat Torlak

Switching Functions
Recall basic elements of communications network:
Terminals, transmission media, and switches

Basic function of any switch is to set up and release connections between transmission channels on an “asneeded basis” Computers are used to control the switching functions of a central office

EE4367 Telecom. Switching & Transmission

Prof. Murat Torlak

Switching Types
Two different switching technologies
Circuit switching Packet switching

EE4367 Telecom. Switching & Transmission

Prof. Murat Torlak

CircuitCircuit-Switched Network
Circuit-Switched network assigns a dedicated communication path between the two stations. It involves Point to Point from terminal node to network Internal Switching and multiplexing among switching nodes. Data Transfer. •Blocking Networks (voice) Circuit Disconnect.

Advantages

•Non-Blocking Networks (computer)

Once connection is established Network is transparent. Nodes seems to be directly connected. Fixed data rate with no delay.

Disadvantages
Can be inefficient...
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