Tag: Circuit Switching

Message Switching | Switching Techniques

Computer Networks

Switching in Computer Networks-

 

The process of moving the data packets towards their destination by forwarding them from one port to the other port is called as switching.

 

Switching Techniques-

 

Various switching techniques are-

 

 

  1. Circuit Switching
  2. Message Switching
  3. Packet Switching

 

In this article, we will discuss about Message Switching.

 

Message Switching-

 

In message switching,

  • There exists no dedicated path to transfer data.
  • The entire message is treated as a single data unit.
  • The message is then forwarded from hop to hop.
  • Store and Forward is an important characteristic of message switching.
  • The message carries a header that contains the full information about the destination.
  • When any intermediate switch receives the message, it stores the entire message.
  • The message is stored until sufficient resources become available to transfer it to the next switch.
  • When resources become available, the switch forwards the message to the next switch.

 

Advantages-

 

Point-01:

 

  • It improves the channel efficiency over Circuit Switched Network.
  • In circuit switched network, the channel is blocked for two ends only.
  • But here, more devices can share the channel.

 

Point-02:

 

  • It is helpful in reducing traffic congestion.
  • The message may be temporarily stored in the route and then forwarded whenever required.

 

Point-03:

 

  • It is helpful in setting the message priorities due to store and forward technique.

 

Disadvantages-

 

Point-01:

 

  • It requires enough storage at every switch to accommodate the entire message during the transmission.

 

Point-02:

 

  • It is extremely slow due to store and forward technique.
  • Also, the message has to wait until sufficient resources become available to transfer it to the next switch.

 

Message switching is replaced by Packet switching.

 

To gain better understanding about Message Switching,

Watch this Video Lecture

 

Next Article- Packet Switching

 

Get more notes and other study material of Computer Networks.

Watch video lectures by visiting our YouTube channel LearnVidFun.

Circuit Switching in Networking | Switching

Computer Networks

Switching in Computer Networks-

 

The process of moving the data packets towards their destination by forwarding them from one port to the other port is called as switching.

 

Switching Techniques-

 

Various switching techniques are-

 

 

  1. Circuit Switching
  2. Message Switching
  3. Packet Switching

 

In this article, we will discuss about Circuit Switching.

 

Circuit Switching-

 

This switching technique operates in the following three phases-

  1. Establishing a circuit
  2. Transferring the data
  3. Disconnecting the circuit

 

1. Establishing A Circuit-

 

In this phase,

  • A circuit is established between the two ends.
  • Circuit provides a dedicated path for data to travel from one to the other end.
  • Resources are reserved at intermediate switches which are used during the transmission.
  • The intermediate switches are connected by the physical links.

 

 

2. Transferring The Data-

 

After the circuit is established,

  • The entire data travels over the dedicated path from one end to the other end.

 

3. Disconnecting The Circuit-

 

After the data transfer is completed,

  • The circuit is torn down i.e. disconnected.

 

Total Time-

 

Total time taken to transmit a message in circuit switched network

= Connection set up time + Transmission delay + Propagation delay + Tear down time

 

where-

  • Transmission delay = Message size / Bandwidth
  • Propagation delay = (Number of hops on way x Distance between 2 hops) / Propagation speed

 

Also Read- Packet Switching

 

Advantages-

 

Circuit switching has the following advantages-

  • A well defined and dedicated path exists for the data to travel.
  • There is no header overhead.
  • There is no waiting time at any switch and the data is transmitted without any delay.
  • Data always reaches the other end in order.
  • No re ordering is required.

 

Disadvantages-

 

Circuit switching has the following disadvantages-

  • The channel is blocked for two ends only.
  • It is inefficient in terms of utilization of system resources.
  • The time required for establishing the circuit between the two ends is too long.
  • Dedicated channels require more bandwidth.
  • It is more expensive than other switching techniques.
  • Routing decisions can not be changed once the circuit is established.

 

Important Notes-

 

  • Circuit switching is implemented at physical layer.
  • Circuit switching is now outdated.

 

PRACTICE PROBLEM BASED ON CIRCUIT SWITCHING TECHNIQUE-

 

Problem-

 

Consider all links in the network use TDM with 24 slots and have a data rate of 1.536 Mbps. Assume that host A takes 500 msec to establish an end to end circuit with host B before begin to transmit the file. If the file is 512 kilobytes, then how much time will it take to send the file from host A to host B?

 

Solution-

 

Given-

  • Total bandwidth = 1.536 Mbps
  • Bandwidth is shared among 24 slots
  • Connection set up time = 500 msec
  • File size = 512 KB

 

Calculating Bandwidth Per User-

 

Total bandwidth = Number of users x Bandwidth per user

So, Bandwidth per user

= Total bandwidth / Number of users

= 1.536 Mbps / 24

= 0.064 Mbps

= 64 Kbps

 

Calculating Transmission Delay-

 

Transmission delay (Tt)

= File size / Bandwidth

= 512 KB / 64 Kbps

=  (512 x 210 x 8 bits) / (64 x 103 bits per sec)

= 65.536 sec

= 65536 msec

 

Calculating Time Required To Send File-

 

Time taken to send a file in circuit switched network

= Connection set up time + Transmission delay

= 500 msec + 65536 msec

= 66036 sec

= 66.036 msec

 

To gain better understanding about Circuit Switching,

Watch this Video Lecture

 

Next Article- Message Switching

 

Get more notes and other study material of Computer Networks.

Watch video lectures by visiting our YouTube channel LearnVidFun.