IPv4 Addresses: 5% Left

Discussion in 'NZ Computing' started by Lawrence D'Oliveiro, Oct 19, 2010.

  1. Lawrence D'Oliveiro, Oct 19, 2010
    #1
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  2. Lawrence D'Oliveiro

    Gunnar Gren Guest

    Gunnar Gren, Oct 19, 2010
    #2
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  3. Lawrence D'Oliveiro, Oct 19, 2010
    #3
  4. Lawrence D'Oliveiro

    peterwn Guest

    Why are 224-255 unusable? What are they otherwise 'used' for which
    makes them unusable.

    There are probably 'kludges' available of the type, for example, where
    the London telephone system was split into two concentric zones as an
    interim measure until 8 digit numbers could be introduced.
     
    peterwn, Oct 19, 2010
    #4
  5. Lawrence D'Oliveiro

    David Empson Guest

    Addresses starting with 224 through 239 are for multicasts. They can't
    be reassigned because there will be existing devices that are using
    addresses in those ranges for multicasts, and routers and hosts will
    assume that is what they are for.

    Addresses starting with 240 through 255 are "reserved for future use"
    according to various networking/IP textbooks (I haven't hunted down the
    RFCs), and at least 255.255.255.255 is used for local broadcast. Some
    references suggest this range can be used for "research and development
    purposes".

    I expect a problem with reassigning 240 through 254 is that lots of
    routers and hosts will not allow addresses in that range to be used,
    because they are/were officially reserved.
     
    David Empson, Oct 20, 2010
    #5
  6. Lawrence D'Oliveiro

    Matty F Guest

    It's a very basic flaw in system design to have a fixed length field
    that eventually overflows, requiring a huge amount of work to make the
    field larger, until the next time it overflows again.
     
    Matty F, Oct 20, 2010
    #6
  7. In message
    Given that IPv6 has room for roughly the same number of addresses as the
    estimated number of atoms in the entire observable Universe, how soon will
    it be do you think before we have to go through the pain all over again and
    move to IPv7?
     
    Lawrence D'Oliveiro, Oct 20, 2010
    #7
  8. Lawrence D'Oliveiro

    victor Guest

    A very basic flaw in universe deign
     
    victor, Oct 20, 2010
    #8
  9. Lawrence D'Oliveiro

    Matty F Guest

    The number of atoms in the Universe seems to have shrunk by a huge
    margin.
    Some programmers are very wasteful of resources. Whatever is
    available, they will waste. However IPv6 should be enough.
    Why didn't they use IPv6 in the first place?
     
    Matty F, Oct 20, 2010
    #9
  10. Lawrence D'Oliveiro

    peterwn Guest

    Because IPV4 would have seemed ample at the time, so much so that some
    large USA companies like IBM and MS were allocated a 'A' group eg
    ccc.xxx.xxx.xxx where the whole x range was allocated to them.

    Similarly phone companies thought that seven digit numbers and a USA
    area code system with 128 or so area codes was adequate.

    In such cases there was a requirement at the time to accommodate
    technological and perceived human limitations, eg phone companies
    considered a seven digit number was as much as a person could handle
    (especially with the traditional spin dial), and even then the first
    three should be a 'letter code' (even if random letters like in
    Sydney, etc). Also for example 40-50 years ago it was considered that
    people would never be able to dial international calls because of
    alleged complexity.
     
    peterwn, Oct 20, 2010
    #10
  11. Lawrence D'Oliveiro

    Squiggle Guest

    Why did the phone company not start with 7 digit phone numbers from
    first manual exchange?
     
    Squiggle, Oct 20, 2010
    #11
  12. Lawrence D'Oliveiro

    Gib Bogle Guest

    We are all clever with hindsight.
     
    Gib Bogle, Oct 20, 2010
    #12
  13. Lawrence D'Oliveiro

    David Empson Guest

    Hardly. 128 bits is about 3e38 IPv6 addresses.

    12 grams of carbon-12 contains 6e23 atoms, and the mass of the Earth is
    5.9e24 kg (3.5e48 if it was all C-12), so there aren't enough IPv6
    addresses for every atom on Earth, let alone the whole universe.

    It works out to slightly less than one IPv6 address per square picometre
    on Earth's surface. (Earth's surface area being 5.1e8 square
    kilometres.)
     
    David Empson, Oct 20, 2010
    #13
  14. Lawrence D'Oliveiro

    Squiggle Guest

    The overhead of transmitting IPv6 sized addresses on the modems of the
    day (1200 bps) would be one very good reason not to have used IPv6 sized
    addresses. >20% of the bandwidth available would have been required
    for transmitting addresses at one packet per second.
     
    Squiggle, Oct 20, 2010
    #14
  15. In message
    We’re talking pre-PC era, back when computers, at least ones powerful
    enought to be worth networking, were hefty boxes that had to live in their
    own special rooms. Nobody ever thought we’d have a billion computers like
    that. And indeed, we never did.
     
    Lawrence D'Oliveiro, Oct 21, 2010
    #15
  16. Lawrence D'Oliveiro

    victor Guest

    The resources of routers
     
    victor, Oct 21, 2010
    #16
  17. Lawrence D'Oliveiro

    peterwn Guest

    They effectively did in big cities. You gave the operator the central
    office name and number eg Pennsylvania 5000 for New York's
    Pennsylvania Hotel. When the London and New York phone systems were
    automated, the number became PENnsylvania 5000, and when NY Phone
    Company ran out of relevant names, PEnnsylvnia 6-5000 (as in the Glen
    Miller song), and finally 736 5000, so the hotel has effectively had
    the same phone number for 100 years or so.

    In these cities if you dialled a manual number from an automatic
    phone, the last four digits were displayed to the 'B' operator who
    then completed the call manually. This enabled central offices to be
    progressively converted without the need to notify everyone of number
    changes.

    Letters on phone push buttons follow original USA practice. The
    British moved the letter O to zero, and the French added Q to zero (eg
    ROQuet 1234), and the Aussies went off on a real tangent having a
    single letter on each dial hole so phone numbers were like number
    plate numbers. The advent of international dialling (originally by
    phone operators) brought these variations to a head - hence all digit
    numbers.
     
    peterwn, Oct 21, 2010
    #17
  18. Lawrence D'Oliveiro

    Dave Doe Guest

    Our old boat, Hinemoa, has a plate above the door with the boat builders
    4 digit Auckland phone number.
     
    Dave Doe, Oct 21, 2010
    #18
  19. Lawrence D'Oliveiro

    Dave Doe Guest

    Prolly need IPv7 within ten years, LOL
     
    Dave Doe, Oct 21, 2010
    #19
  20. Lawrence D'Oliveiro

    Matty F Guest

    I invented a principle (but somebody else may have thought of it
    first) that when you are designing something, assume that it is going
    to succeed, and design accordingly to allow it to be scaled up.
     
    Matty F, Oct 21, 2010
    #20
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