Data Link Layer

RamsesK

hello everyone i have a question about the physical and data link layers about this, i have understood that the data link layer converts packets from network layer into frames, and now i see it converts also in the Mac Sublayer the frames into bits wich i find pretty logical, but was not the physical layer the one who make the convertion of frames into bits?

if not the Data Link Layer has two conversions in it, packets to frames and frames to bits (MAC Sublayer) to then let the physical layer manage this data in to the cables (physical media) :

keenon

RamsesK wrote:

hello everyone i have a question about the physical and data link layers about this, i have understood that the data link layer converts packets from network layer into frames, and now i see it converts also in the Mac Sublayer the frames into bits wich i find pretty logical, but was not the physical layer the one who make the convertion of frames into bits?

if not the Data Link Layer has two conversions in it, packets to frames and frames to bits (MAC Sublayer) to then let the physical layer manage this data in to the cables (physical media) :

here is the short version

Data link is concerned with the logical connection to the network ethernet, frame-relay and atm for example .. it uses frames

Physical is deals with the type of media cable types copper or fiber .. or even the wireless antenna.. voltage


but for the test datalink= frames
physical= bits

RamsesK

ok got it! thanks!!!!!!!!!!

but... for our personal records is really the Mac sublayer who deal with the bits in the NIC card as the following part of the technotes says right?????

MAC sublayer

The Media Access Control layer takes care of physical addressing and allows upper layers access to the physical media, handles frame addressing, error checking. This layer controls and communicates directly with the physical network media through the network interface card. It converts the frames into bits to pass them on to the Physical layer who puts them on the wire (and vice versa)

from this concept and some others this belongs to the datalink layer but we will figure it as it doesn't for the test am i right?

thanks

/usr

The Technotes are right.

Webmaster

It's basically like this: the physical layer handles raw bits, it speaks 'bits'. It communicates with the physical layer at the communication partner. So when your computer receives bits, the physical layer pulls them off the media (wire, ether) and passes them up the OSI layer to the Data Link layer (MAC sublayer) which handles frames. Now imagine the other way around (you sending traffic), the physical layer understands only bits (it doesn't know how these bits form a frame or packet or data).

A layer in the OSI model communicates with the layer above it, the layer below it, and the same layer on the other side of the connection. In case of the physical layer there is no layer below it. The information the physical layer receives from the layer above it, has to be in bit format.