[PLUG] Linux OSI Model

Randy.Dunlap rddunlap at osdl.org
Sun Mar 24 21:04:03 UTC 2002


On Sun, 24 Mar 2002, Rick Konold wrote:

| On Sunday 24 March 2002 12:02, you hammered the keyboard to write:
| > On Sun, 24 Mar 2002, Rick Konold wrote:
| > | I was doing some reading that covered the OSI model again, and remembered
| > | learning that Microsoft has combined some of the layers so that their
| > | implementation is actually 4 layers, but includes all of the 7 layers of
| > | the OSI model.  Does Linux use all 7 layers ala the OSI, or are some of
| > | them combined?
| >
| > OSI was a nice theory...
| > Does anything (outside of government) use all 7 layers of OSI?
| > Not that I know of.  TCP/IP is a 4- or 5-layer model.
| > Linux doesn't even pretend to use the OSI model.
|
| Does Linux use TCP/IP as the model?  I mean, I am trying to get a picture of

Yes (AFAIK).

| what happens from the Application level to Physical level in Linux.  So far,
| I have this picture:

Yes, this matches what I found via google fairly well.
I searched for "tcp/ip networking model" and got 200,000 hits,
such as:
  http://userpages.umbc.edu/~jack/ifsm498d/tcpip-intro.html

I'm sure that some of these web pages can answer your
questions...and I can't.

  ~Randy

| Application level : FTP, HTTP, SMTP etc.
| (I assume the session level is rolled into the application level)
|
| Transport Layer : Port / sequence numbering (any error checking here?)
| TCP UDP (any others?)
|
| Network Layer : IP addressing
|
| Data LInk Layer : (this is done on the NIC?) Hardware addressing. Error
| checking (any packet sequencing at this level?)
|
| Physical Layer : the actual transmission via Ethernet or ? electrically
|
| Does this look correct?
| Are packets sized at the transport layer?
|
| >
| > | Also, when using bitwise notation for a subnet mask, will the routing
| > | table actually accept /20, or do I have to write it out as 255.255.240.0
| > | ?
| >
| > don't know.
|
| Thats ok, I can wait until I get the router working and try to change it then
| to see what happens.
| _______________________________________________





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