RE: subnetting C class into /26 /25 /26, why can this be done?

From: Clark Gaylord (cgaylord_at_vt.edu)
Date: 08/27/03

  • Next message: Olivier Nicole: "Re: subnetting C class into /26 /25 /26, why can this be done?" 
    To: "'Christoffer Pio'" <cp@cvt.dk>
Date: Wed, 27 Aug 2003 17:47:08 -0400

    When in doubt, do it in binary:
       0 = 00000000
      64 = 01000000
     128 = 10000000
     192 = 11000000
    As a /26 (taking as given the 24 x's not shown for the other three octets):
           xxyyyyyy - y's are the host
                      xx doesn't have the same value from 64-191
    As a /25:
           xyyyyyy - y's are the host
                     x doesn't have the same value from 64-191

    A /26 means there are 26 bits of network and 6 bits of host; a /25 means 25
    bits of network and 7 for host.

    As /26's xx = {00, 01, 10, 11} for the four distinct values, with the other
    six bits signifying the host address. As /25s x = {0, 1} are the two
    distinct values. Now, you could use 0/25 (as 0-127 all have same first bit)
    and 128/26 and 192/26 as each of these network address bits (10 and 11) stay
    the same through the respective block of addresses.

    Hopefully this helps.
    Clark

    > -----Original Message-----
    > From: owner-freebsd-net@freebsd.org
    > [mailto:owner-freebsd-net@freebsd.org] On Behalf Of Christoffer Pio
    > Sent: Wednesday, August 27, 2003 10:04 AM
    > To: freebsd-net@freebsd.org
    > Subject: subnetting C class into /26 /25 /26, why can this be done?
    >
    >
    > Is it not possible to subnet a C class into 3 nets, like
    >
    > 0-63
    > 64-191 <-- Offending network (?)
    > 192-255
    >
    > If so, why is this?
    >
    > Christoffer
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    > http://lists.freebsd.org/mailman/listinfo/f> reebsd-net
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  • Next message: Olivier Nicole: "Re: subnetting C class into /26 /25 /26, why can this be done?"

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