What happens if I send a packet from my PC to an offline PC with different gadgets?

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canadianvice
About the only way a PC listens for a packet when it's off is if it has an option in the BIOS for something called "Wake on LAN" which is when it receives a special packet telling the computer to turn on.

Otherwise, the packet basically just bounces around as devices try to route it to a nonexistent address, and eventually its TTL (time to live) reaches 0 and it is terminated, lost to all.

Seeing as you seem to be interested in this sort of line of questioning, it's really straight forward:
It does not matter what devices you plug in between your computer and your router, be it switches, other routers, or adapters, if your computer is off and it is not for the specific case I mentioned above, the packet will be lost and nothing will...
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vascobrissos14

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So if the PC that should get the message is offline, the message is lost, in a switch. Right?

Does this also apply to MAUS? (Probable yes?)

Thanks
 
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vascobrissos14

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And the PC is only offline. Still connected to the PSU and to the ethernet cable. The PC is just turned off.
 
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canadianvice

canadianvice

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About the only way a PC listens for a packet when it's off is if it has an option in the BIOS for something called "Wake on LAN" which is when it receives a special packet telling the computer to turn on.

Otherwise, the packet basically just bounces around as devices try to route it to a nonexistent address, and eventually its TTL (time to live) reaches 0 and it is terminated, lost to all.

Seeing as you seem to be interested in this sort of line of questioning, it's really straight forward:
It does not matter what devices you plug in between your computer and your router, be it switches, other routers, or adapters, if your computer is off and it is not for the specific case I mentioned above, the packet will be lost and nothing will happen.
 
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vascobrissos14

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Thank you!

You really explained it very well.
I'm actually running a RPI 3 as a VPN server and a wake on lan "server" so I can use my laptop and stream my desktop's screen to my school. So I have a small knowledge of this matter.

I thought that if the PC is off, it just never gets the packets (unless the Magic one's but they don't really matter here) but I'm not any expert and that thought was only my thought, based on what I know and that's not that much.

That's why I came here to ask someone like you to explain it like you did.

Again, thanks a lot for replying! It really helps me out at school :p
 
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bill001g

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First question to ask the instructor is "Is this a networking history class?". Hubs and especially token ring mau have not been used for getting close to 20 years now. Maybe you should ask them if you can still back up your programs to paper tape or maybe punch cards.

Any test questions that even mention this equipment are pretty much invalid.

You will only see switches.

What a switch does depends on timing and how long its been since it last saw traffic from a device.

If it receives a packet with a mac address it does not know it sends it out all port other than the one it received it on. This feature can be disabled on many managed switch.

If it knows the mac address it will send it only out on the port it has mapped to that mac address.

In general if you were to unplug a port it will immediately flush the mapping for the port. If the port is physically active then it will keep the mac mapped to that port for 5 minutes before it deletes it. So for the first 5 minutes it will send the traffic down the old port after that it will send it to all ports.

In any case the packet are not discarded by the switch they are always sent someplace except in the rare case that there is only a single port active on that network.

So the answer to your question I suspect is much more complex that you thought.
 
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vascobrissos14

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Hey

We are starting to get on this matter so we are learning everything that has been used, but after that, we will only focus on the switches and more recent stuff.
I think the teacher is doing it right. We should know what existed before today's stuff, right?
Thanks for your answer! I didn't understand much but I will discuss it with my teacher! :)
 
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bill001g

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Learning old technology that is not used just makes things more confusing. It might be taught after you learn the current methods just as a comparison. I know most the cisco certs no longer test a number of things that are not supported on cisco router any more. This tend to be how I know if the instruction material is old. If you see any so called cisco certification stuff that talks about RIPv1 or HSRP you know it is outdated.

It is much simpler to learn the way that works now and then after you can learn about strange stuff that used to cause issues that they solved via technology. It not like a car mechanic need to know what to feed his horse
 
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vascobrissos14

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Well, you got your point. My teacher also got his point. I'll discuss this thread with him tomorrow!

 
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bill001g

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Just as a point I recently retired but have held a CCIE cert for more than 15 yrs. I have actually used token ring when I first start, it was pretty much only used by IBM mainframes and they did not even use IP addresses they used a completely different protocol called VTAM.
 
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