switching

Switching

Switching is one of the most important aspect of computer networking. In todays world we use internet quite often from searching information, watching videos to all our bank operational stuffs. Well this has been possible just because of switching. So, what is switching that might be the first question one may ask. Switching is basically the mechanism of information exchange between computer networks and network segments.

Switching can be classified in two segments: -

Connection oriented switching-

    i.Handshaking will be there.
ii.In this handshaking generally strobe signals are used.
iii.Each packet is sent through the same route
iv.For faster data transfer, we use connection-oriented switching.
v.Example- ATM, PCM, frame relay
vi.Basically, there are 3 phases in this-
a.Connection will be set-up or connection set-up
b.Data will be transmitted or data transmission
c.Release 

Connectionless switching-

            i.Handshaking is not there.

        ii.Each packet is sent in a different route

        iii.Example- IP, UDP

Now the overall switching techniques can be divided into three categories-

        Circuit switching

   Message switching

   Packet switching

lets discuss all the three type of techniques in detail.

Circuit Switching-

i.It involves end to end switching. A path is set up for the 
communication between the receiver and sender during the
 session.

ii.Its commonly used in the telephonic services.

iii.No delay will be allowed in circuit switching

iv.Basically, it passes through 3 phases.

a.Circuit establishment

b.Data transfer

c.Circuit discharge

v.In circuit switching high bandwidth will be required.

vi.The major drawback of this technique is that the link of this 
connection can’t be used to send data when its free. 

       Message switching

i.This technique lies somewhere in the middle

circuit switching and packet switching.

ii.Here each message is treated as an independent

unit.

iii.In this type of switching, the switch first receive

the entire the entire message, buffers it and waits 

until there are resources available to transfer to the

 next hub.

iv.This technique is also known as store and forward

 switching.

v.The very big advantage of using this technique is 

that it manages the traffic very efficiently.

vi. A major drawback here will be the delay which

 is caused due to the store and forward mechanism.

vii.Also, a very large capacity is required.

viii.Here the chances of error occurrence will be less

 as we are sending a block of data at a time.

ix. A hop if not having space or having less space

 will not take any more data but will wait until space

 is created.

x.A very good example of this would be the

 telegraphic services.

    Packet switching: -

i.The shortcomings of message switching gave rise 

to the creation of another type of switching 

technique called packet switching.

ii.In this technique the message is broken into

 smaller fragments called packets. The information

 required for switching is added to the header of 

each individual packet and then transmitted 

independently.

iii.There are basically two types of packet switching.

a.Datagram packet switching which is also a 

connectionless switching.

b.Virtual packet switching which is also 

connection-oriented switching.

iv.In this type of switching both the wireless and

 wired components are present.

v.This technique has an advantage as the 

intermediate network devices can store small size

 packets and do not take much resources either in the

 carry path or in the internal memory of switches.

vi.If one of the links fail, other can be used.

vii.Here high memory space is required.

viii.The biggest advantage of this type of technique

 is that multiple packets can be multiplexed over the 

carrier. The internet uses packet switching.

ix.Correction circuit is present at every point. It can

 follow any path.

x.Packets are stored and provided according to their 

priority.