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mac or ip communication ?

Discussion in 'Networks' started by kobem, Mar 14, 2007.

  1. kobem

    kobem Megabyte Poster

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    i know that hosts communicate via hardware addresses
    on the local LAN

    but why do we use ip addresses for pcs in local area network?

    for ex. there are too many pcs connected to one same
    switch , while they are contacting we give ip addresses
    to hosts then why?
     
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  2. BosonMichael
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    BosonMichael Yottabyte Poster

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    To understand why, you need to understand the OSI model. Google for it. It's not easy to understand at first glance, but over time, it will become easier to understand.

    MAC addresses are physical addresses. IP addresses are logical addresses. MAC addresses give no clue as to the location of the device; IP addresses do.
     
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  3. Mr.Cheeks

    Mr.Cheeks 1st ever Gold Member! Gold Member

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    each pc or nodes has its own ip address to ensure there are no conflicts between nodes, plus it helps identify the pc, the concept is similar to web addresses...

    also note what BBM mentioned re MAC addresses aswell.

    in your example, what do you mean by "too many pcs connected to one same switch " ?
     
  4. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    You need IP addresses for the TCP/IP stacks in the computers to work.

    There is no software on a standard PC that communicates on just Ethernet alone.

    As others have said - read up on the OSI stack.

    Harry.
     
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  5. Sparky
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    Sparky Zettabyte Poster Moderator

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    Also if you go to a command line and type arp -a it will show you the arp cache which has I.P addreses and which MAC addresses are assigned to them.

    As the other guys have said, revise the OSI model and things will be much clearer*


    * = never thought I would say that about the OSI model! :biggrin
     
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  6. BosonMichael
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    BosonMichael Yottabyte Poster

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    ...and if you don't learn it the first time, it'll haunt you forever, because it NEVER goes away... especially for certification exams.
     
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  7. kobem

    kobem Megabyte Poster

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    hmm people , i know how OSI works

    lets say encapsulation thing for the name of it

    but think then switch doesn't understand the ip address
    since its osi layer 2 device (1 and 2 )

    so while we put pcs and a switch connected to each
    switch uses address filtering but in the beginning it doesn't know
    the destination mac so it broadcasts all other hosts and
    from the port except the port it received the frame.
    then when i response from a host is received
    by switch , frame goes to right destination (by registering
    in filter table)

    and switch doesn't understand ip (cause
    it is layer 2)

    here above there no looks like ip addresses
    so what do you say about ip on pcs?
     
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  8. zebulebu

    zebulebu Terabyte Poster

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    Kobem - reading your posts hurts my brain... :biggrin

    Do you not have someone who can articulate what you're trying to say a bit better? I know thats a bit of a cheek, since whatever language you speak I probably couldn't communicate with you nearly as well as you can in English!

    Basically, the OSI model is your friend. You'll need to know it inside and out for pretty much any networking exam you take - although its relevance is often not exactly apparent to many day to day tasks you'll encounter in the real world, for understanding something like this it really is useful.

    Layer 2 communication works on MAC addresses, whilst Layer 3 communication works with IP addresses (or other such protocols). This is one of the basic differences between traditional switching and routing.

    Hopefully This article will help explain things for you more clearly than I could ever hope to do.
     
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  9. mondos

    mondos Kilobyte Poster

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  10. kobem

    kobem Megabyte Poster

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    you meant this

    while pcs communicating , they use mac
    but for "location detection" they use ip addresses

    ok but switch doesn't understand ip address?:biggrin
     
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  11. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    I had to read the above several times to get to the point that I thought I understood what you were trying to say.

    This is pretty much how a switch works. So what is the question?

    Harry.
     
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  12. BosonMichael
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    BosonMichael Yottabyte Poster

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    If you truly understood the OSI model, you'd not have a question about why we use IP addresses vs. MAC addresses.

    Shoulda known better than to try to answer a kobem question... :dry
     
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  13. kobem

    kobem Megabyte Poster

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    nearly i found the answer

    when a host tries to communicate with another
    ARP is used that specifies ip address converting to mac
    in local LAN

    so we need ip addresses on hosts.
     
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  14. Sparky
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    You didnt expect to route data on MAC addresses alone did you? :biggrin
     
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  15. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    That's back to front in my view. ARP exists to allow IP networks to find local hosts on an Ethernet network.

    If it wasn't an Ethernet network you wouldn't find ARP either.

    Harry.
     
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  16. kobem

    kobem Megabyte Poster

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    what do you mean sparky?
     
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  17. BosonMichael
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    Lawn chair... check.

    Coke Classic... check. :morebeer

    Popcorn... check. :popcorn

    Okay... I'm ready for the entertainment.
     
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  18. Bluerinse
    Honorary Member

    Bluerinse Exabyte Poster

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    Feet up

    Beer in hand

    Light a ciggy..

    Waiting Sparky....

    :twisted:
     
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  19. Boycie
    Honorary Member

    Boycie Senior Beer Tester

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    Kobem,

    I see your original question has been answered.

    TCP and the OSI model is big topic that has had entire books devoted to the subject. May I suggest you take a look at this excellent website?;

    TCP/IP Guide
     
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  20. Sparky
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    Sparky Zettabyte Poster Moderator

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    Awww ffs!!!!! :biggrin :biggrin

    Based on your previous posts I don’t think you really understand the OSI model. Don’t get me wrong I’m sure you could name each layer and perhaps a few details about it but beyond that I’m not so sure.

    Going back to my ‘You didnt expect to route data on MAC addresses alone did you?´ post which I wish I didn’t blurt out think about it for a few minutes and it will make sense.
     
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