Self Doubt.

Question

Can anyone please explain this?

Answer 1

$number\ of\ times\ a\ packet\ visits\ network\ layer$

$ 1\ source\ +\ 1\ router\ +\ 1\ destination\ =\ 3$

$ number\ of\ times\ a\ packet\ visits\ data\ link\ layer$

$ 1\ source\ +\ 2\ router\ +\ 1\ destination=4$

Comments

I want to ask that in router why DLL,PL is 2 & NL is 1?

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A Router is network layer device.

When a packet travels from source to destination it starts from top to bottom layer at source and visits 1 time network layer and 1 time DLL.

At router packet goes bottom to top and after that top to bottom bcoz it's router so packet to be returned from network layer and visits 1 time network layer and 2 times DLL.

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Still i didn't visualized.

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See at router packet is 2 times crossing DLL once bottom to top and 2nd top to bottom it is given in diagram

Still problem then ping me GO telegram group wl share image there

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In router the packet goes like (Bottom To Up) physical link → DLL → NL (Now Top to Bottom) → DLL → physical link, that’s it.
If you are thinking that the packet is going in the NL only one time but not two time, now think why would you want your packet to go twice in the NL. Please also consider in your mind the concept of adding or removing header from each layer.