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I am having a tough time understanding the network layer or layer 3 in the OSI model. Could anyone please help me with my questions

1)correct me if I am wrong, from my understanding the basic task of the network layer is to allow communication between two end devices that are on different networks and for that to be possible, the network layer has to send data via the internet.

2)If the answer to question 1 is YES then could it mean that if two computers within the same network wish to exchange data then there is no point in the network layer interfering?

3)Is there a difference between layer 3 of the OSI model and the internet layer of the TCP/IP model?

Any help is greatly appreciated, thank you very much in advance!

user207421
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Ryuzakii
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  • You can ask about [tag:tcp] or you can ask about [tag:osi] but you can't ask about them both at the same time, because the meanings of the layers are different in each. – user207421 Oct 10 '21 at 23:14

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the basic task of the network layer is to allow communication between two end devices that are on different networks and for that to be possible, the network layer has to send data via the internet.

The end nodes may be in different networks (connected by gateways) but they don't need to. Traffic only crosses the Internet when it's routed across, using public addressing.

could it mean that if two computers within the same network wish to exchange data then there is no point in the network layer interfering?

The network layer (IP) is required by common protocols (e.g. HTTP requires TCP which requires IP). It's perfectly possible to communicate within a local network using the data link layer alone (Ethernet usually), but it's very uncommon and may be complicated using modern operating systems, especially for an unprivileged application.

Is there a difference between layer 3 of the OSI model and the internet layer of the TCP/IP model?

The internet layer in the TCP/IP model doesn't entirely adhere to the OSI concept of network layer, but it's very much the same thing.

Zac67
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  • thank you for answering my question I understand for the most part thanks to your explanation. In your second answer you said that TCP requires IP, is this for the IP addressing? thank you – Ryuzakii Oct 14 '21 at 15:39
  • @Ryuzakii There's no host-to-host connectivity function in TCP (or in transport-layer protocols generally), that's IP's job. – Zac67 Oct 14 '21 at 16:34