Switching technique is the technique used and applied on a big network. When these huge networks need to move packets from source to destination, i.e. from sender to receiver, switching techniques come into play. The packet, which is ready for transmission from source to destination, must trace the route over which the packets will be transmitted. Switching is the process of picking the best available route for data transmission of packets from source to a receiver. Circuit switching and packet switching are two popular switching strategies, each with its own significance.

There may be multiple pathways from source to receiver in huge networks.
The data transmission route will be determined by the switching strategy.

To connect the systems for one-to-one communication, a switching approach is used.

 

Classification Of Switching Techniques

Circuit Switching

Circuit switching is a method of establishing a dedicated path between the transmitter and the receiver. Once a link is created via the Circuit Switching Technique, the dedicated path will remain active until the connection is canceled. In a network, circuit switching functions similarly to how a telephone works. Before communication takes place, there must be a complete end-to-end channel.

When using the circuit switching technique, when a user wishes to communicate data, voice, or video, they send a request signal to the receiver, who then sends back an acknowledgment to guarantee the dedicated path is available. After getting the acknowledgment, the data is transferred through a designated channel. In the public telephone network, circuit switching is employed. It is used to transmit voice.

Circuit switching technology allows for the transfer of fixed data at a single moment.

There are three phases to circuit switching communication:

1. Circuit establishment
2. Data transfer
3. Circuit Disconnect

Circuit Switching can use either of the two technologies:

Space Division Switches:

Space Division Switching is a circuit switching mechanism that uses a physically separate set of crosspoints to create a single transmission line in a switch. Crossbar switches can be used to achieve space division switching. A crossbar switch is a metallic crosspoint or semiconductor gate that a control unit can enable or disable. The semiconductor is used to create the Crossbar switch. Switches in Space Division Switching are high-speed, high-capacity, and nonblocking.

Space Division Switches are categorized in two ways:

• Crossbar Switch
• Multistage Switch

Crossbar Switch

A switch with n input lines and n output lines is known as a Crossbar switch.
The crossbar switch has n2 intersection points called crosspoints.

The disadvantage of Crossbar switch:

As the number of stations increases, so does the number of crosspoints. As a result, a large switch becomes extremely expensive. A multistage switch can be used to solve this problem.

Multistage Switch

The crossbar switch is broken into smaller units and then interconnected to create a multistage switch. The number of crosspoints is reduced. In the event that one path fails, another will be available.

Advantages Of Circuit Switching:

• The communication channel is specialized in the Circuit Switching technique.
• It has a predetermined bandwidth.

Disadvantages Of Circuit Switching:

• The only delay in data transmission happens once the dedicated path is established.
• Establishing a connection takes a long time, about 10 seconds, during which no data may be sent.
• Because each connection requires a dedicated path, it is more expensive than other switching techniques.
• It is inefficient to utilize since the capacity of the path is wasted after the path is built and no data is sent.
• Because the connection is dedicated in this case, even if the channel is free, no other data can be sent.

Message Switching

Message switching is a switching technique in which a message is sent in its whole and routed to intermediate nodes where it is stored and delivered. A dedicated path between the sender and recipient is not established in the Message Switching technique. The message’s destination address is attached to it. Message Switching allows for dynamic routing by routing messages through intermediate nodes based on the information included in the message. Message switches are set in such a way that the most efficient routes are available. Every node saves the complete message before passing it on to the next node.
The store and forward network is the name for this type of network. Each message is treated as a separate object when using message switching.

Advantages Of Message Switching

• Data channels are shared among connected devices, allowing for better usage of existing bandwidth.
• Because the message is temporarily stored in the nodes, traffic congestion can be reduced.
• To manage the network, message priority can be applied.
• The message size that is sent over the network can be changed.
  As a result, it can handle data of any scale.

Disadvantages Of Message Switching

• The message switches must have enough storage to keep the messages until they are forwarded.
• The storing and forwarding capability afforded by the message switching technique can cause a long delay.

Packet Switching

Packet switching is a switching technique in which a message is split into smaller pieces and transmitted separately rather than being sent all at once. The message is broken down into smaller pieces known as packets, each of which is assigned a unique number to identify its place in the receiving order. The headers of each packet contain information such as the source address, destination address, and sequence number.

Packets will travel the shortest path available across the network. At the receiving end, all of the packets are reassembled in the correct order. If one or more packets are missing or malformed, the message will be sent again.

Approaches Of Packet Switching:

There are two approaches to Packet Switching:

Datagram Packet switching:

It’s a packet-switching technology in which each packet, referred to as a datagram, is treated as a separate entity. The destination information is contained in each packet, and the switch uses this information to forward the packet to the correct destination. At the receiving end, the packets are reassembled in the correct order.

The path is not specified in the Datagram Packet Switching technique. To forward packets, intermediate nodes make routing decisions. Connectionless switching is another name for datagram packet switching.

Virtual Circuit Switching

Connection-oriented switching is another name for virtual circuit switching. Before the messages are sent, a preplanned path is constructed with virtual circuit switching. The sender and receiver create a connection using call requests and call accept packets. The path is fixed in this scenario for the duration of the logical connection.

Advantages Of Packet Switching:

• Switching devices do not require massive secondary storage to store packets in packet-switching techniques, therefore costs are reduced to some extent. As a result, we can conclude that packet switching is a cost-effective strategy.
• Reliable: Packets can be rerouted if one or more nodes are busy. As a result, the Packet Switching approach assures that communication is reliable.
• Packet Switching is a cost-effective strategy. It does not require a pre-established path for transmission, and multiple users can use the same communication channel at the same time, maximizing available bandwidth.

Disadvantages Of Packet Switching:

• The packet switching technology is incompatible with applications that require a low delay and high-quality services.
• The protocols used in packet-switching are extremely complex and expensive to implement.
• If the network is overloaded or corrupted, lost packets must be retransmitted.
  It can also result in the loss of vital data if errors are not corrected.