Packet Switching

Packet means a segment of information. This segment of information has a size. Yes, the size is that of the information that lies in the packet. We know that the size of information is expressed in bytes. 

Information travels through Networks in the form of packets. In a particular collection all the packets have equal size. If we talk of packets elsewhere, then size may be different. 

Packets can be sent over telecommunications lines. Such activities result in assured delivery of packets to the receiver. Yes, such transportation over physical links is reliable. 

At a time only one packet can be sent over a telecommunications line. When the line becomes free, the next packet can be sent. When a packet is sent over a communication line, communication may succeed or fail. The success or failure of the communication process is related to transmission of previous and subsequent packets. This is true in cases where communication uses physical connections such as telecommunications lines. Use of physical connections also means that importance is given to ordered delivery of packets.

Packets can be sent in another way. In this method the presence of physical connection is not required. Here, a packet is stored on a node. From this node it is forwarded to another node. This method is called 'Store and Forward'. The 'Store and Forward' method is fast. The disadvantage is that it is not as  reliable as the previous  method using physical connections. 

In the absence of physical connections, ordered delivery of packets is not possible. This Network Service is called datagram service. The datagram service is known for speedy delivery of packets. This service is not reliable. Packets are delivered without any order. The case of missing packets is also seen. At the receiver point the packets are reassembled. The complete information is thus obtained. 

It can be easily concluded that Packet Switching can be done using physical connections or without any physical connection. Both the methods have advantages and disadvantages.