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I have the following network

enter image description here

It is really a simple network and routing table of both routers consist of directly connected networks only, meaning, no routing is being done here. Now, it is obvious that PC0 network and Server0 network are not connected, however, i am interested to see what happens if we try to send packet through the network.

Let's say that i try to send simple request-response message using TCP (HTTP for example) form PC0 to Server0, what will happen when Router0 drops packet, is Router going to inform PC that his packet failed (it should, since TCP is used)? What kind of messages will be sent? Will PC0 try to send packet again and again? Any help appreciated!

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  • Based on how the Router is configured it will reply to the client with an ICMP message. I. E.: ciscoskills.net/2011/08/24/the-codes-of-icmp This will also be the same with TCP
    – Pompi
    Feb 16 '19 at 12:19
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can provide and accept your own answer.
    – Ron Maupin
    Dec 14 '19 at 20:06
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routing table of both routers consist of directly connected networks only,

That is a problem - Router0 doesn't know where Server0 is located, Router1 doesn't know where PC0 is located.

meaning, no routing is being done here.

Not true. If PC0 uses Router0 as gateway it can talk to Router1 (and likewise Server0 to Router0) via routing.

Now, it is obvious that PC0 network and Server0 network are not connected, however, i am interested to see what happens if we try to send packet through the network.

It won't work. PC0 sends the packet to Router0 (assuming PC0's got a route) and Router0 drops it, lacking a route to destination.

is Router going to inform PC that his packet failed (it should, since TCP is used)?

It should. TCP doesn't matter (routers don't care for transport-layer protocols) but IP does.

What kind of messages will be sent?

It should send ICMP Destination Unreachable, Code 0 (Network Unreachable).

Will PC0 try to send packet again and again?

That is up to PC0 and host configurations are off-topic on NE. Usually, it won't send the packet again unless it has other gateway options.

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