Why is IP addrssed used if MAC is there to make an endoint unique ? - TCP-IP

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Thread: Why is IP addrssed used if MAC is there to make an endoint unique ?

  1. Why is IP addrssed used if MAC is there to make an endoint unique ?

    Hi,

    Why is IP addrssed used if MAC is there to make an endoint unique ?

    Thanks,
    Siddharth

  2. Re: Why is IP addrssed used if MAC is there to make an endoint unique ?

    In article <9ca3861b-ef7f-4252-95c8-67f7d11fe69c@x16g2000prn.googlegroups.com>,
    sidd wrote:

    >Why is IP addrssed used if MAC is there to make an endoint unique ?


    MAC is only required to be unique per LAN.

    MACs are organized by manufacturer, not by some kind of
    logical connectivity. What mechanism do you propose to allow your
    equipment where-ever to find an efficient path to my equipment
    over here, when your equipment could turn out to have a MAC that is
    just one digit different than mine, or your equipment could turn
    out to have a MAC that is completely different from mine?

  3. Re: Why is IP addrssed used if MAC is there to make an endoint unique ?

    In article
    <9ca3861b-ef7f-4252-95c8-67f7d11fe69c@x16g2000prn.googlegroups.com>,
    sidd wrote:

    > Hi,
    >
    > Why is IP addrssed used if MAC is there to make an endoint unique ?


    MAC addresses don't contain network location information that helps you
    figure out how to get packets to the LAN that the endpoint is on.

    It's like the reason we put addresses rather than social security
    numbers on envelopes.

    --
    Barry Margolin, barmar@alum.mit.edu
    Arlington, MA
    *** PLEASE don't copy me on replies, I'll read them in the group ***

  4. Re: Why is IP addrssed used if MAC is there to make an endoint unique ?

    On Sunday 31 August 2008 20:37, sidd wrote:

    > Hi,
    >
    > Why is IP addrssed used if MAC is there to make an endoint unique ?


    Beyond the other very good reasons already given, there is also the fact
    that MAC addresses are used only in certain kind of networks (eg ethernet).
    There are data-lik technologies that do not use MAC addresses for physical
    addressing.


  5. Re: Why is IP addrssed used if MAC is there to make an endoint unique?

    On Aug 31, 11:37*am, sidd wrote:
    > Hi,
    >
    > Why is IP addrssed used if MAC is there to make an endoint unique ?


    Knowing something unique about someone does not always help you find
    them. Knowing their *location* in a way that makes sense for the
    network you're using, on the other hand, is very useful.

    MAC is a local address, like 'in my kitchen on the leftmost chair'.
    It's great if you're in my house and need to find someone. It's not
    helpful if you're in another city. IP address is more like a postal
    address. It will get you to the right house from any city.

    DS

  6. Re: Why is IP addrssed used if MAC is there to make an endoint unique ?

    sidd wrote:
    > Why is IP addrssed used if MAC is there to make an endoint unique ?


    Because historically not all network endpoints used Ethernet. A modem link
    is a classic and common example where you can have an IP address endpoint
    without having a MAXC address. In fact many point-to-point links did not
    (and do not) have MAC addresses. Plus, there were other competing link
    layer protocols that had their own address schemes back when the Internet
    Protocol was designed.

    Lastly, using MAC addresses requires dispensing with address subnets, which
    help reduce the size of routing tables to manageable sizes and minimize
    table update requirements.

  7. Re: Why is IP addrssed used if MAC is there to make an endoint unique ?

    In article
    <272c7971-b232-47e4-8039-eb3e86d7223f@k36g2000pri.googlegroups.com>,
    David Schwartz wrote:

    > MAC is a local address, like 'in my kitchen on the leftmost chair'.
    > It's great if you're in my house and need to find someone. It's not
    > helpful if you're in another city. IP address is more like a postal
    > address. It will get you to the right house from any city.


    Sorry, I already used that analogy a couple of days ago, you're going to
    have to find your own.

    --
    Barry Margolin, barmar@alum.mit.edu
    Arlington, MA
    *** PLEASE don't copy me on replies, I'll read them in the group ***

  8. Re: Why is IP addrssed used if MAC is there to make an endoint unique ?

    Barry Margolin wrote:
    > In article
    > <272c7971-b232-47e4-8039-eb3e86d7223f@k36g2000pri.googlegroups.com>,
    > David Schwartz wrote:
    >
    >> MAC is a local address, like 'in my kitchen on the leftmost chair'.
    >> It's great if you're in my house and need to find someone. It's not
    >> helpful if you're in another city. IP address is more like a postal
    >> address. It will get you to the right house from any city.

    >
    > Sorry, I already used that analogy a couple of days ago, you're going to
    > have to find your own.


    Boy, it's a lucky thing that I decided not send the followup I was
    composing earlier today that criticized that analogy. I would have been
    insulting more than one person! ;-)

    Um, wait a tick... !

  9. Re: Why is IP addrssed used if MAC is there to make an endoint unique ?

    In article ,
    Jim Logajan wrote:

    > Barry Margolin wrote:
    > > In article
    > > <272c7971-b232-47e4-8039-eb3e86d7223f@k36g2000pri.googlegroups.com>,
    > > David Schwartz wrote:
    > >
    > >> MAC is a local address, like 'in my kitchen on the leftmost chair'.
    > >> It's great if you're in my house and need to find someone. It's not
    > >> helpful if you're in another city. IP address is more like a postal
    > >> address. It will get you to the right house from any city.

    > >
    > > Sorry, I already used that analogy a couple of days ago, you're going to
    > > have to find your own.

    >
    > Boy, it's a lucky thing that I decided not send the followup I was
    > composing earlier today that criticized that analogy. I would have been
    > insulting more than one person! ;-)
    >
    > Um, wait a tick... !


    I got an email reply the other day praising my analogy, and asking
    permission to incorporate it into their site. I guess you can't please
    everyone.

    --
    Barry Margolin, barmar@alum.mit.edu
    Arlington, MA
    *** PLEASE don't copy me on replies, I'll read them in the group ***

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