IP subnetting - TCP-IP

This is a discussion on IP subnetting - TCP-IP ; eager wrote: > if the subnet bits are all zero - that is the network address of that > subnetwork > if the subnet bits are all one - that is the multicast of that subnetwork No, you're talking about ...

+ Reply to Thread
Page 2 of 2 FirstFirst 1 2
Results 21 to 29 of 29

Thread: IP subnetting

  1. Re: IP subnetting

    eager wrote:

    > if the subnet bits are all zero - that is the network address of that
    > subnetwork
    > if the subnet bits are all one - that is the multicast of that subnetwork


    No, you're talking about the host bits, not the subnet bits.


  2. Re: IP subnetting

    In article , pk writes:
    > eager wrote:
    >
    >> if the subnet bits are all zero - that is the network address of that
    >> subnetwork
    >> if the subnet bits are all one - that is the multicast of that subnetwork

    >
    > No, you're talking about the host bits, not the subnet bits.


    I believe that he is talking about the subnet bits.

    The rules for classful subnetting appear in RFC 950. Those rules specify
    a standard way to split up classful (Class A, Class B or Class C) networks
    into smaller pieces.

    Without subnetting, an IP address can be thought of as having two
    pieces, a network number and a host number within that network.
    The class of the address determines which bits are part of the network
    number and which bits are part of the host number.

    For instance, classically speaking, 172.16.1.10 falls within a class
    B network. So it has network number <172.16> and host <1.10>

    RFC 950 prescribed a scheme for subdividing the host portion of a
    network address so that the resulting IP addess could be thought of
    as having three pieces, a network number, a subnet number and a host
    number within that subnet.

    The bits that fell within the network number field were still determined
    by the address class. The subnet field consisted of those host bits that
    corresponded to "1" bits in the netmask. The host field consisted of
    those host bits that corresponded to "0" bits in the netmask.

    For instance, 172.16.1.10 under a 255.255.255.0 netmask would have been
    network number <172.16>, subnet <1> and host <10>.

    Under the RFC 950 subnetting scheme, the all zeroes subnet number and the
    all ones subnet numbers were reserved. The former was to have been used
    to represent "this subnet" and the latter to represent "all subnets".

    From RFC 950:

    It is useful to preserve and extend the interpretation of these
    special addresses in subnetted networks. This means the values
    of all zeros and all ones in the subnet field should not be
    assigned to actual (physical) subnets.

    In the example above, the 6-bit wide subnet field may have
    any value except 0 and 63.

    As a practical matter, RFC 950 is a dead letter. CIDR is the way
    the IPv4 space is used today. An IP address is now best thought of as
    having two pieces, a prefix (network number) and suffix (host number).

    The prefix length is now determined by a network mask. Network masks
    are now required to have all the 1 bits on the left and all the 0 bits
    on the right. The prefix length is the number of 1 bits. The address
    "class" does not enter in.

  3. Re: IP subnetting

    briggs@encompasserve.org wrote:

    >> No, you're talking about the host bits, not the subnet bits.

    >
    > I believe that he is talking about the subnet bits.
    >
    > The rules for classful subnetting appear in RFC 950. Those rules specify
    > a standard way to split up classful (Class A, Class B or Class C) networks
    > into smaller pieces.
    >[cut]
    > For instance, 172.16.1.10 under a 255.255.255.0 netmask would have been
    > network number <172.16>, subnet <1> and host <10>.
    >
    > Under the RFC 950 subnetting scheme, the all zeroes subnet number and the
    > all ones subnet numbers were reserved. The former was to have been used
    > to represent "this subnet" and the latter to represent "all subnets".


    Agreed, but this is not what eager said.

    >> eager wrote:
    >>> if the subnet bits are all zero - that is the network address of that
    >>> subnetwork
    >>> if the subnet bits are all one - that is the multicast of that
    >>> subnetwork


    According to "classical" definitions, the "network address" of a network (or
    subnetwork) is the network address itself, with all the host bits set to
    zero. Similarly, the "broadcast (not multicast) address" of a network is
    the network address itself, but with all the host bits set to one. These
    two addresses are still reserved.
    Note that, given a subnetting scheme, there is a "network address" and
    a "broadcast address" *for each subnet*, while, given a subnetting scheme.
    there is only one "all-zero" subnet and only one "all-one" subnet.

    > As a practical matter, RFC 950 is a dead letter. CIDR is the way
    > the IPv4 space is used today. An IP address is now best thought of as
    > having two pieces, a prefix (network number) and suffix (host number).


    Agreed, but a network admin can still subnet the address space assigned to
    him, so the "network-subnet-host" subdivision may still make sense in
    certain scenarios.

    > The prefix length is now determined by a network mask. Network masks
    > are now required to have all the 1 bits on the left and all the 0 bits
    > on the right. The prefix length is the number of 1 bits. The address
    > "class" does not enter in.


    Again, agreed.


  4. Re: IP subnetting


    "pk" wrote in message news:fnmofi$h9n$1@aioe.org...
    > eager wrote:
    >
    >> if the subnet bits are all zero - that is the network address of that
    >> subnetwork
    >> if the subnet bits are all one - that is the multicast of that
    >> subnetwork

    >
    > No, you're talking about the host bits, not the subnet bits.
    >


    Then, you have no clue what a subnet mask is and why we use it.



  5. Re: IP subnetting


    wrote in message
    news:8JkV2cNAFWcR@eisner.encompasserve.org...
    > In article , pk writes:
    >> eager wrote:
    >>
    >>> if the subnet bits are all zero - that is the network address of that
    >>> subnetwork
    >>> if the subnet bits are all one - that is the multicast of that
    >>> subnetwork

    >>
    >> No, you're talking about the host bits, not the subnet bits.

    >
    > I believe that he is talking about the subnet bits.
    >
    > The rules for classful subnetting appear in RFC 950. Those rules specify
    > a standard way to split up classful (Class A, Class B or Class C) networks
    > into smaller pieces.
    >
    > Without subnetting, an IP address can be thought of as having two
    > pieces, a network number and a host number within that network.
    > The class of the address determines which bits are part of the network
    > number and which bits are part of the host number.
    >
    > For instance, classically speaking, 172.16.1.10 falls within a class
    > B network. So it has network number <172.16> and host <1.10>
    >
    > RFC 950 prescribed a scheme for subdividing the host portion of a
    > network address so that the resulting IP addess could be thought of
    > as having three pieces, a network number, a subnet number and a host
    > number within that subnet.
    >
    > The bits that fell within the network number field were still determined
    > by the address class. The subnet field consisted of those host bits that
    > corresponded to "1" bits in the netmask. The host field consisted of
    > those host bits that corresponded to "0" bits in the netmask.
    >
    > For instance, 172.16.1.10 under a 255.255.255.0 netmask would have been
    > network number <172.16>, subnet <1> and host <10>.
    >
    > Under the RFC 950 subnetting scheme, the all zeroes subnet number and the
    > all ones subnet numbers were reserved. The former was to have been used
    > to represent "this subnet" and the latter to represent "all subnets".
    >
    > From RFC 950:
    >
    > It is useful to preserve and extend the interpretation of these
    > special addresses in subnetted networks. This means the values
    > of all zeros and all ones in the subnet field should not be
    > assigned to actual (physical) subnets.
    >
    > In the example above, the 6-bit wide subnet field may have
    > any value except 0 and 63.
    >
    > As a practical matter, RFC 950 is a dead letter. CIDR is the way
    > the IPv4 space is used today. An IP address is now best thought of as
    > having two pieces, a prefix (network number) and suffix (host number).
    >
    > The prefix length is now determined by a network mask. Network masks
    > are now required to have all the 1 bits on the left and all the 0 bits
    > on the right. The prefix length is the number of 1 bits. The address
    > "class" does not enter in.


    Thanks man, and it's very nice of you to provide such a detailed INFO.
    I normally do not put that much energy to explain stuff to people that do
    not want to listen



  6. Re: IP subnetting

    eager wrote:

    > Then, you have no clue what a subnet mask is and why we use it.


    Well, read my other answer. You probably don't have the notion
    of "subnetting" very clear.


  7. Re: IP subnetting

    eager wrote:

    > Thanks man, and it's very nice of you to provide such a detailed INFO.
    > I normally do not put that much energy to explain stuff to people that do
    > not want to listen


    How does what you said relate to what briggs said?

    Reread what you wrote:

    "if the subnet bits are all zero - that is the network address of that
    subnetwork
    if the subnet bits are all one - that is the multicast of that subnetwork"

    and the RFC briggs cited says

    "The bits that fell within the network number field were still determined
    by the address class. *The subnet field consisted of those host bits that
    corresponded to "1" bits in the netmask. *The host field consisted of
    those host bits that corresponded to "0" bits in the netmask.
    For instance, 172.16.1.10 under a 255.255.255.0 netmask would have been
    network number <172.16>, subnet <1> and host <10>.
    Under the RFC 950 subnetting scheme, the all zeroes subnet number and the
    all ones subnet numbers were reserved. *The former was to have been used to
    represent "this subnet" and the latter to represent "all subnets"."

    Ignoring the fact that "the multicast of a subnetwork" is a non-existent
    concept, can't you see that you said something quite different
    (furthermore, badly worded)?

    At least read your own posts before uttering nonsense.


  8. Re: IP subnetting


    "pk" wrote in message news:fnnlcn$n1i$1@aioe.org...
    > eager wrote:
    >
    >> Thanks man, and it's very nice of you to provide such a detailed INFO.
    >> I normally do not put that much energy to explain stuff to people that do
    >> not want to listen

    >
    > How does what you said relate to what briggs said?
    >
    > Reread what you wrote:
    >
    > "if the subnet bits are all zero - that is the network address of that
    > subnetwork
    > if the subnet bits are all one - that is the multicast of that
    > subnetwork"
    >
    > and the RFC briggs cited says
    >
    > "The bits that fell within the network number field were still determined
    > by the address class. The subnet field consisted of those host bits that
    > corresponded to "1" bits in the netmask. The host field consisted of
    > those host bits that corresponded to "0" bits in the netmask.
    > For instance, 172.16.1.10 under a 255.255.255.0 netmask would have been
    > network number <172.16>, subnet <1> and host <10>.
    > Under the RFC 950 subnetting scheme, the all zeroes subnet number and the
    > all ones subnet numbers were reserved. The former was to have been used to
    > represent "this subnet" and the latter to represent "all subnets"."
    >
    > Ignoring the fact that "the multicast of a subnetwork" is a non-existent
    > concept, can't you see that you said something quite different
    > (furthermore, badly worded)?
    >
    > At least read your own posts before uttering nonsense.
    >


    Maybe my answer is too deep for you to grasp, that's ok; not many people
    understand subnetting and especially multicasting.
    Besides, common sense is for common people, so I am not surprised you find
    my answer as "nonsense".

    For the records

    "the all zeroes subnet number and the all ones subnet numbers were reserved.
    The former was to have been used to
    represent "this subnet" [ my answer: "if the subnet bits are all zero - that
    is the network address of that subnetwork]
    and the latter to represent "all subnets" [my answer: "if the subnet bits
    are all one - that is the multicast of that subnetwork"]

    If you will ever understand subnetting, and you seem to need a really good
    teacher for that, then you will realize the " - 2" in the formula when you
    calculate the number of subnets and the number of hosts per subnet. That's
    exactly it! The key to your answer is to understand the "-2".

    Good luck and thanks for wasting my time again.






  9. Re: IP subnetting

    eager wrote:

    > Maybe my answer is too deep for you to grasp, that's ok; not many people
    > understand subnetting and especially multicasting.


    If you knew at least something of each, you would know that these are two
    completely distinct and unrelated subjects.

    > Besides, common sense is for common people, so I am not surprised you find
    > my answer as "nonsense".
    >
    > For the records
    >
    > "the all zeroes subnet number and the all ones subnet numbers were
    > reserved. The former was to have been used to
    > represent "this subnet" [ my answer: "if the subnet bits are all zero -
    > that is the network address of that subnetwork]
    > and the latter to represent "all subnets" [my answer: "if the subnet bits
    > are all one - that is the multicast of that subnetwork"]
    >
    > If you will ever understand subnetting, and you seem to need a really good
    > teacher for that, then you will realize the " - 2" in the formula when you
    > calculate the number of subnets and the number of hosts per subnet. That's
    > exactly it! The key to your answer is to understand the "-2".
    >
    > Good luck and thanks for wasting my time again.


    Nobody forced you to waste your time. You could remain silent and use your
    time for more useful things (perhaps studying subnetting?).

    Instead, you insist on showing your total cluelessness about the matter.
    The -2 when calculating the number of subnets is obsolete, that's why the
    all-zero and all-one subnets can be used nowadays. Your sources are
    obsolete.
    As for the "multicast of that subnetwork" (which you still fail to explain)
    being equal to "all subnets"...well, if you haven't understood it yet, I'm
    not certainly wasting more time trying to explain the concept to you.
    Ah but yes, I suppose that your "common sense" says that they are the same
    thing. Sorry, I have no common sense, as you correctly pointed out.

    On the other hand, you are very strong in trolling.


+ Reply to Thread
Page 2 of 2 FirstFirst 1 2