Check out this article on Cisco web
site.
Also, this page shows how TCP/IP layers
function.
Basically, I see alot of people trying to make
everything "fit into layers". Just remember that in the OSI model, there
are certain functions that are associated with each layer. You could have
a protocol, like IPX from the IPX/SPX suite, that does functions of Layer 3
(logical addressing/path determination) and Layer 4 (connectionless, needs SPX
to be connection oriented), so it's hard to say that it's a Layer 3 or Layer 4
protocol, because it actually performs functions of both. Since the
Department of Defense (DOD) designed the TCP/IP protocol suite and it's
"reference layers" before the OSI reference model was created, they made their
own layers. Here's a rough approximation of how these layers line up: (I
hope your using a fixed width font =)
OSI Model
Layers
TCP/IP Model Layers
----------------
-------------------
Application --------+
Presentation --------+------------>
Application
Session --------+
Network <------------------------->
Network
Data Link <----------------------->
Data Link
Physical <------------------------>
Physical
As you can see, the *functions* of the OSI
Application/Presentation/Session are all handled by just the Application layer
in the TCP/IP model. So, for instance, even thought FTP is in the
Application Layer in the TCP/IP model, it handles the application interface (OSI
Application Layer), the formatting of data to/from the application (OSI
Presentation Layer), and opening/closing the session (OSI Session
Layer).
I hope this helps some..........
Mike W.
Sammi <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED]...
> Hello,> I understand TCP/IP packets, and the OSI Network Model 7 layers.
> However I'm not sure what is meant by TCP/IP layers? Would this be
> reference to the 4 layer IPX model:
> Application/Transport/Network/Physical, but upon typing I see that
> doesn't make sense either.
> I guess I have to ask straight out: What is the first layer of TCP/IP?
> From there I should be able to research relevant material.
> Thanks, again, for your help.
>
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