Switching takes extra transmission time?

Question

We know,  Packet Switching works like pipelining. It makes transmission time less. But, we do switching with switching delay, then it add extra transmission time.Why?

Not getting reason for this.

Chk this question for reference:https://gateoverflow.in/8495/gate2015-3_36

Here switching adding extra transmission time. Means 2 packet has has transmission time for both. Still one more transmission tim will be added for switching.Can u plz give reason for it?

Comments

Okay I get it.

See the link A-S-B

Packet 1 is sent from A to S. Here once 500 will be added.

Packet 1 is sent from S to B. Here again 500 will be added.

Also, when packet 1 is done being sent to S. Packet 2 will begin to transmit on the line from A to S. Now this 500 is in parallel with Packet 1 transmitted from S to B. So, we won't add it again. Thus packet 2 from A to S and packet 1 from S to B happen at same time.

When packet 2 will completely reach S, it'll start it's journey to B. Now, from S to B, the 500 is considered. So, for the third time 500 is added.

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u mean switch work same as router ?

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Not exactly same. But to the context of this question, the intermediate device should have the functionality for packet forwarding. Both does that.