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<DIV><FONT face=Arial size=2>Hello again Heath</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I didn't see the second question and since no one
else appears to have responded (probably sensibly having a day off) I'll give it
a go</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV><![if !supportLists]><![endif]><![if !supportLists]><![endif]><![if !supportLists]><![endif]><![if !supportLists]><![endif]><![if !supportLists]><![endif]>
<DIV><SPAN
style="FONT-SIZE: 11pt; FONT-FAMILY: 'Calibri','sans-serif'">Question: Is it
possible to classify switches hubs and NICs into the physical layer because they
are hardware and the cables plug into them, while the data travelling through
these devices is on an upper level? Or is a NIC always on the data layer and
switches somewhere between data and network layers?</SPAN></DIV>
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<DIV><FONT face=Arial size=2>Switches hubs etc cannot be placed in the physical
layer simply because they are hardware - afterall the computer we transmit
messages from is also hardware. It depends on what protocol issues they have to
deal with (possibly via firmware programming). So</FONT></DIV>
<DIV><FONT face=Arial size=2>- hubs are purely layer 1 since all they do is send
a received signal to all ports - they in effect just repeat the signal, they
have no understanding of the content of that signal</FONT></DIV>
<DIV><FONT face=Arial size=2>- switches need to know which port to send
received data down so they need to know about physical addressing within a
network which means being able to read data link (layer
2) frames</FONT></DIV>
<DIV><FONT face=Arial size=2>- routers need to know about the end to end
addressing so they operate up to the network layer (3)</FONT></DIV>
<DIV><FONT face=Arial size=2>- NICs transform computer 1's and 0's into whatever
the transmission medium requires so they are definitely layer 1. But it could
depend on the kind of network they connect into; for example, collision
detection in Ethernet is done in hardware on the NIC, but I'm pretty sure that
collision detection (and then dealing with it) is a layer 2 function - I stand
to be corrected on this. Also NICs are responsible for MAC addresses which is a
layer 2 function. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I hope this is helpful</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Regards</FONT></DIV>
<DIV><FONT face=Arial size=2>Robert T-A</FONT></DIV>
<DIV><FONT face=Arial size=2>Brighton SC</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
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