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OSI MODEL Question

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by robert.hawley

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I was recently in a discusion about the OSI model and related test questions.
The question that created a such a dillema was this.
What layer of the OSI model does the NIC belong on?
We all know what Cisco says but what do you think, Layer 1 or layer 2?

12 replies

by ghstinshll

So if I think it's L1, what does Cisco say "officially"? L1 translates frames into bits for placement on media, it's just that simple. A NCI does this.

by robert.hawley

Why do you think they reside on layer 2?

On one hand the NIC convertes frames to bits to pulses of elctricity, this is all layer one functionality, But on the other it also holds the MAC address and strips that portion of the packet off to compare it. This is layer 2 functionality.

The layer two portion is handeled by whatever framing convention that is on the firmware of the card (802.2, 802.3, 802.5 etc).

by madroxxx

You have to place a decive on the top layer it operates and it is assumed that it also uses the layers below it. For example a router is a layer 3 device but also operates on layer 2,1. A network card broadcasts data to MAC addy's and therefore is layer 2. Of course it operates on layer 1 as well.

by wornk2

This is a dilemmia in teaching the CCNA cirrulum. Even tho the NIC is a physical device -- Cisco considers this a Layer 2 device. read on how the Data Link layer is divided into two parts (LLC and MAC)

by robert.hawley

Well following that logic routers are application then, because they use TFTP. That is the highest protocol they use.

by madroxxx

While a Router does use TFTP for it's own updates that is not it's purpose. It's purpose is to route. This happens at layer 3. A network cards purpose is to transfer data to another device, this happens at layer 2&1.

by robert.hawley

True,
But the purpose of a NIC card is to trasmit data via pullses of electricty doen the cable, the firmware and drivers (both software) handeling the framming.

by max98037

The jack in the back is physical. The MAC is data link. It deals in frames, so if a question only allows one choice, then Data Link all the way!!

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