OSI model
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Thread: OSI model

  1. #1
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    OSI model

    i hear from my prof that osi reference model is not used and seldom was,then why do i have to study that in my network paper

  2. #2
    Senior Member PacketThirst's Avatar
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    OSI reference model not used ??? ..... OSI ISO model divides the complex process of networking into seven distinct but interrelated layers.So the benefit is that each layer
    can concentrate on its task thereby helping the upper layers.Also vendors can concentrate
    their products on a particular task/layer. ISO makes things easier !!

  3. #3
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    Maybe your prof was just joking and you took him to be serious. If it wasn't for the OSI model, the networks as we know them would not be. The OSI Reference Model is a standard for all communicating devices so that they can talk to eachother.

    TCP/IP may be a little different, I think it only has 4 layers, where OSI has 7, but they still follow the same general rule. When you send info from one computer to another, it uses the OSI model to turn the data into segments, packets, frames, and then binary code in the form of analog/digital/radio/light signals. It goes from Layer 7 (Application) down to Layer 1 (Physical). When the data is received at the other end, it goes from layer 1 up to layer 7, turning the raw binary code back into the data. If it wasn't for the OSI model, this process would become too complex. What if the other computer tried to re-assemble the packet differently?

    Put it this way, if it weren't for the OSI Model (or a different standard), a network would become a place where thousands of different languages are flying around in no particular order, and communication would never happen.

    The OSI Model is definately alive and well. Learn it, study it, understand it. If you are like me and going for CCNA and CCNP, you have to know it. Perhaps your prof just meant that you don't really have to know it to plug computers together, just like you don't really have to know how physics works to drive a car. In my studies, the OSI Model is like god...


    Regards,


    Dave
    Alcohol & calculus don't mix. Never drink & derive.

  4. #4
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    Ask him to describe the difference between a layer 2 and layer 3 switch then tell you again about the OSI model..

  5. #5
    ********** |ceWriterguy
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    Your prof is probably unschooled into the depth of protocols and protocol stacks. He is quite unaware that when he sends this or that across the net exactly what happens to make those nice little *standardized* packets that any system can read, but only the one it's addressed to gets (yes, I'm not counting sniffers here, this is basic stuff).

    The reason for the model is to set a standard from which all protocols are based, so that computers everywhere can communicate - it's the very foundation of networking. Without it, we'd be blocked from communication by 'language barriers' between computers. (hence the International Standards Organization invented it).

    Tell Prof to stick that in his pipe with whatever else he's been smoking.

    /me looks up 2 posts and sees that this has already been stated in a much larger form and apols for repeating.
    Even a broken watch is correct twice a day.

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  6. #6
    Master-Jedi-Pimps0r & Moderator thehorse13's Avatar
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    This isn't the first time I have heard this nonsense. You wouldn't be a University of Maryland student would you? Tell him that all the computing models in the world have moved on to layer 8 and layers 1-7 are no longer needed.
    Our scars have the power to remind us that our past was real. -- Hannibal Lecter.
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  7. #7
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    Yeah, and speaking of switches, just imagine compairing a Hub to a Switch. Why are switches so much better? Why don't you see hubs as much as before? Don't they do the same thing?

    HELL NO. Hubs are Layer 1 devices, basically just multi-port repeaters. Switches work on Layer 2, the 'Data Link' layer. Therefore Switches are better because since they work on Layer 2, they offer MAC filtering to help keep wasted traffic flow down. (Though as ss2chef said, there are Layer 3 switches too, which are more advanced. I haven't studied them yet, though I'm guessing they would even offer some kind of IP filtering as well as MAC filtering.)

    If it wasn't for the OSI model, how could we have come to the conclusion that Switches are better than hubs?

    Dude, seriously, get a different prof, lol :P



    Dave
    Alcohol & calculus don't mix. Never drink & derive.

  8. #8
    AO Ancient: Team Leader
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    i hear from my prof that osi reference model is not used and seldom was
    Dammit, dammit, dammit.....

    This means that I have to read another 20 bloody networking books to find out what we are using today..... My brain's already full.....

    This is why those that are graduating with their batchelors and masters in computer science are no use whatsoever to me..... Because their professors are dumber than the students.... Unfortunately, the students feel some strange desire to listen to the dimwits!!!!!

    xmeta: While there is no real need to "use it" in day to day network administration it is imperative that you understand it exists and how and why it works. If you don't know about it and how it works then you will never understand how your network is working.... The unfortunate lot of many admins today..... That's all well and good until you have a problem... Then you are at a severe disadvantage.
    Don\'t SYN us.... We\'ll SYN you.....
    \"A nation that draws too broad a difference between its scholars and its warriors will have its thinking done by cowards, and its fighting done by fools.\" - Thucydides

  9. #9
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    OSI knowledge can be helpful in troubleshooting and although it's in the abstract, it's used in this
    forum quite a bit. When questions are being thrown about.

    When you have your T1 provider on the phone about a down line and they tell you they have
    layer 2 connectivity from the ATM cloud to your DSU, you should probably know what they are talking about..

  10. #10
    AO Ancient: Team Leader
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    SS2.... Yeah.... that's what I said.... You were just more direct..... I want him to apply himself to it by making it sound a little "important".... becuase when he interviews with me I might ask him about it to see if his prof knew his ****....
    Don\'t SYN us.... We\'ll SYN you.....
    \"A nation that draws too broad a difference between its scholars and its warriors will have its thinking done by cowards, and its fighting done by fools.\" - Thucydides

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