1. Circuit & Packet Switching

2. ► Two ways of achieving the same goal. ► The transfer of data across networks. ► Both methods have advantages and disadvantages.

3. Circuit Switching

4. ► A connection path is established between sending & receiving nodes. ► All data follows the same physical path between sender & receiver. ► Lasts as long as it takes to transmit all data. ► ISDN & Dial-up connections

5. Circuit Switching ► Circuit switched connections take time to establish, up to 10 to 20 seconds. ► Quality can vary with each connection. ► Not efficient as communications channels are generally not used to full capacity. ► More expensive.

6. Packet Switching ► Does not establish a connection for the entire transmission period. ► The message is divided into packets and each individual packet can take a different path through the network. ► Each packet is given a destination address (IP) and sequence number (TCP).

7. Packet Switching

8. ► Packets can be routed to avoid congestion ► Therefore, better bandwidth use. ► Packets from different sources can share the same lines. ► Usually much cheaper than circuit switching.

9. Packet Switching ► There is a processing overhead at the receiving end as messages need to be reconstructed having arrived in the wrong order. ► Data transfer can be slower than circuit as the connection is shared with other data.