Message are divided into smaller pc called packets each packet includes source & destination address information so that individual packets can be rounded through the inter network indepently.
To common method of packet switching are:
1. Data Gram.
2. VC (virtual circuit).
DATA GRAM PACKET SWITCHING
Data gram services treat each packet as an independent message. Each packet is routed through inter network independently & each switch node determines which network segments should be used for the next Step in the packets route. This capability enables switches to bypass busy segments and that other steps speed packets through the inter network.
Data Gram are frequently used on LAN.
VC PACKET SWITCHING
VC operates by establishing a formal connection b/w two devices in communication. When devices begin a section, they negotiate communication parameters such as maximum msg size, communication window & networks path. This negotiation establish a VC which is a well define path through the inter network by which devices communicates.