How does Router know where to forward packet

Posted by kornelijepetak on Super User See other posts from Super User or by kornelijepetak
Published on 2010-02-07T13:11:07Z Indexed on 2010/03/15 9:10 UTC
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router

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forward

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local

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packets

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tcp

If several computers with local addresses (192.168.0.#) are connected to a router and each computer opens a web browser and requests a page over HTTP, when these TCP:80 packets are sent out, the router switches the local address with the static IP of the router (i.e. Provider given IP) so the server can reply to the appropriate address.

But how does the router know to which computer to forward the HTTP reply, since the TCP header does not contain the local IP address (does it?), and all computers are using port 80?

Does this have anything to do with the MAC addresses?

How exactly does this work?

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