CCNA - TCP/IP Model

Author

TCP/IP Model

iamjoe78

2003-12-06, 11:45 pm

I need some claification on something. First lets state some facts:
*Routers operate at the Internetwork Layer.
*The 1's and 0's are at the Network Interface layer.

So lets say Billy wants to transfer a file to Mikes computer. There is one router between them. How can Billy transfer something from his computer to the router without the data being filtered down to the network interface layer. What I mean is, does Billys data get broken down through all layers then transferred to the router as 1's and 0's? I know that the internetwork layer is above the network interface layer. Confusing to me because there is a physical cable connection between the Billys computer and the router. So Billys data goes all the way down to the Network interface layer and then goes to a Router which operates on the Internetwork Layer?

I wish can put this in a better way, but I don't think I can.

Can someone make sense out of this?

DSComputers

2003-12-07, 1:04 am

When we say a router operates at the network layer, its because that is its primary function. Switches are layer 2, routers are layer 3, hubs are layer 1 (talking osi now) but in reality they all operate at the physical layer as well, theres no way around it.

The only way data can get across a wire is in 1's and 0's, so yes, it goes all the way down to the physical layer or network access layer.
http://www2.rad.com/networks/1994/osi/osi.gif
The dotted lines show where a transmission from one side makes sence to the other side.
But the only way to communicate is the physical layer. Whether a communication starts at layer 3 (say routers updating eachother) or 7 (clicking send in internet explorer) it has to go all the way down, across the wire, and back up to its original layer.

Hope that makes it a little clearer

iamjoe78

2003-12-07, 8:09 am

Thanks, that makes a lot more sense.

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