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SWITCHING TECHNIQUES

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WHAT IS SWITCHING ?

  • When a user accesses the internet or another computer network outside their immediate location, messages are sent through the network of transmission media. This technique of transferring the information from one computer network to another network is known as switching.
  • In large networks, there can be multiple paths from sender to receiver. The switching technique will decide the best route for data transmission.
  • Switching technique is used to connect the systems for making one-to-one communication.

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SWITCHING TECHNIQUE

  • A technique that can determine how connections are made between two different devices and how data movement are handled is called switching .
  • A switched network is consist of series of interlinked nodes called switches .
  • Switches are the networking devices working at the second layer of OSI model i.e. data link layer.
  • Switching in a computer network is achieved by using switches. A switch is a small hardware device which is used to join multiple computers together with one local area network (LAN).
  • A Switch is used to transfer the data only to the device that has been addressed. It verifies the destination address to route the packet appropriately.

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HOW SWITCHING TECHNIQUE WORKS ?

  • All switches transmit data from one location to another location .
  • A switch has many ports , to which computers are plugged in.
  • When the source wants to send the data packet to the destination, the packet first enters the switch and the switch reads its header and finds the MAC address of the destination to identify the device then it sends the packet out through the appropriate ports that lead to the destination devices.
  • Switch establishes a temporary connection between the source and destination for communication and terminates the connection once the conversation is done. Also, it offers full bandwidth to network traffic going to and from a device simultaneously to reduce collision.

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ADVANTAGES OF SWITCHES IN A NETWORK

  • Switching is transparent to the user and does not require any configuration in the home network.
  • Switches are used to forward the packets based on MAC addresses.
  • A Switch is used to transfer the data only to the device that has been addressed. It verifies the destination address to route the packet appropriately.
  • It is operated in full duplex mode.
  • Packet collision is minimum as it directly communicates between source and destination.
  • It does not broadcast the message as it works with limited bandwidth.

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DISADVANTAGES OF SWITCHES

  • A Switch is more expensive than network bridges.
  • A Switch cannot determine the network connectivity issues easily.
  • Proper designing and configuration of the switch are required to handle multicast packets.

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CIRCUIT SWITCHING

  • Circuit switching is a switching technique that establishes a dedicated path between sender and receiver.
  • In the Circuit Switching Technique, once the connection is established then the dedicated path will remain to exist until the connection is terminated.
  • Circuit switching in a network operates in a similar way as the telephone works.
  • A complete end-to-end path must exist before the communication takes place.

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CIRCUIT SWITCH

  • In case of circuit switching technique, when any user wants to send the data, voice, video, a request signal is sent to the receiver then the receiver sends back the acknowledgment to ensure the availability of the dedicated path. After receiving the acknowledgment, dedicated path transfers the data.
  • Circuit switching is used in public telephone network. It is used for voice transmission.
  • Fixed data can be transferred at a time in circuit switching technology.

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ADVANTAGES OF CIRCUIT SWITCH

  • In the case of Circuit Switching technique, the communication channel is dedicated.
  • It has fixed bandwidth.

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DISADVANTAGES OF CIRCUIT SWITCH

  • Once the dedicated path is established, the only delay occurs in the speed of data transmission.
  • It takes a long time to establish a connection approx 10 seconds during which no data can be transmitted.
  • It is more expensive than other switching techniques as a dedicated path is required for each connection.
  • It is inefficient to use because once the path is established and no data is transferred, then the capacity of the path is wasted.
  • In this case, the connection is dedicated therefore no other data can be transferred even if the channel is free.

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MESSAGE SWITCHING

  • Message Switching is a switching technique in which a message is transferred as a complete unit and routed through intermediate nodes at which it is stored and forwarded.

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  • In Message Switching technique, there is no establishment of a dedicated path between the sender and receiver.

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  • The destination address is appended to the message. Message Switching provides a dynamic routing as the message is routed through the intermediate nodes based on the information available in the message.

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MESSAGE SWITCHING

  • Message switches are programmed in such a way so that they can provide the most efficient routes.
  • Each and every node stores the entire message and then forward it to the next node. This type of network is known as store and forward network.
  • Message switching treats each message as an independent entity.

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ADVANTAGES OF MASSAGE SWITCH

  • Data channels are shared among the communicating devices that improve the efficiency of using available bandwidth.
  • Traffic congestion can be reduced because the message is temporarily stored in the nodes.
  • Message priority can be used to manage the network.
  • The size of the message which is sent over the network can be varied. Therefore, it supports the data of unlimited size.

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DISADVANTAGES OF MESSAGE SWITCH

  • The message switches must be equipped with sufficient storage to enable them to store the messages until the message is forwarded.
  • The Long delay can occur due to the storing and forwarding facility provided by the message switching technique.

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PACKET SWITCHING

  • The packet switching is a switching technique in which the message is sent in one go, but it is divided into smaller pieces, and they are sent individually.
  • The message splits into smaller pieces known as packets and packets are given a unique number to identify their order at the receiving end.
  • Every packet contains some information in its headers such as source address, destination address and sequence number.

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PACKET SWITCHING

  • Packets will travel across the network, taking the shortest path as possible.
  • All the packets are reassembled at the receiving end in correct order.
  • If any packet is missing or corrupted, then the message will be sent to resend the message.
  • If the correct order of the packets is reached, then the acknowledgment message will be sent.

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TYPES OF PACKET SWITCHING

PACKET SWITCH

VIRTUAL SWITCH

DATAGRAM SWITCH

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DATAGRAM PACKET SWITCHING

  • It is a packet switching technology in which packet is known as a datagram, is considered as an independent entity. Each packet contains the information about the destination and switch uses this information to forward the packet to the correct destination.
  • The packets are reassembled at the receiving end in correct order.
  • In Datagram Packet Switching technique, the path is not fixed.
  • Intermediate nodes take the routing decisions to forward the packets.
  • Datagram Packet Switching is also known as connectionless switching.

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VIRTUAL CIRCUIT SWITCHING

  • Virtual Circuit Switching is also known as connection-oriented switching.
  • In the case of Virtual circuit switching, a preplanned route is established before the messages are sent.
  • Call request and call accept packets are used to establish the connection between sender and receiver.
  • In this case, the path is fixed for the duration of a logical connection.

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ADVANTAGES OF PACKET SWITCHING

  • Cost-effective: In packet switching technique, switching devices do not require massive secondary storage to store the packets, so cost is minimized to some extent. Therefore, we can say that the packet switching technique is a cost-effective technique.
  • Reliable: If any node is busy, then the packets can be rerouted. This ensures that the Packet Switching technique provides reliable communication.
  • Efficient: Packet Switching is an efficient technique. It does not require any established path prior to the transmission, and many users can use the same communication channel simultaneously, hence makes use of available bandwidth very efficiently.

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DISADVANTAGES OF PACKET SWITCHING

  • Packet Switching technique cannot be implemented in those applications that require low delay and high-quality services.
  • The protocols used in a packet switching technique are very complex and requires high implementation cost.
  • If the network is overloaded or corrupted, then it requires retransmission of lost packets. It can also lead to the loss of critical information if errors are nor recovered.

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