rfc1375.txt

来自「著名的RFC文档,其中有一些文档是已经翻译成中文的的.」· 文本 代码 · 共 395 行 · 第 1/2 页

                        1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         |                                             | Local |
   |1 1 0 1 0|                NETWORK                      |Address|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Proposed "Class F" address

   Class G is to be defined as follows:

        The seventh type of address, class G, is reserved for future
        use.  The six highest-order bits are set to 1-1-0-1-1-0.

                        1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           |                                                   |
   |1 1 0 1 1 0|              Reserved                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Proposed "Class G" address

   Class H is for small networks which are not expected to exceed 7



Robinson                                                        [Page 4]

RFC 1375              New Classes of IP Addresses           October 1992


   connected IP addresses.  Class H is to be defined as follows:

        The eighth type of address, class H, has a 22-bit network
        number, and a 3-bit local address.  The seven highest-order bits
        are set to 1-1-0-1-1-1-0.  This allows 4,194,304 Class H
        addresses [5].

                        1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             |                                           |Local|
   |1 1 0 1 1 1 0|              NETWORK                      | Addr|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Proposed "Class H" address

   Class K is for sites which either will only have one or two connected
   addresses [6].  Class K is to be defined as follows:

        The eighth type of address, class K, has a 25-bit network
        number, and a 1-bit local address.  The seven highest-order bits
        are set to 1-1-0-1-1-1-1.  This allows 33,554,432 Class K
        addresses [7].

                        1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           |                                                 |*|
   |1 1 0 1 0 0|              NETWORK                            | |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       * = Local Address, 1 or 0
                      Proposed "Class K" address

Optional selection of routing codes by region

   Because of the possibility of confusion, some method similar to the
   international dialing plan might be set up, in which bits 5-8 in
   Class F, bits 7-10 in Class H, and bits 6-9 in Class K could be used
   to define what part of the world the particular address is in, in a
   manner similar to the international telephone dialing system, which
   uses the first digit of the international telephone number to
   determine the region being used.  The current method for assigning
   international dialing codes is:







Robinson                                                        [Page 5]

RFC 1375              New Classes of IP Addresses           October 1992


      1 North America               6 Oceania, Australia
      2 Africa                      7 Ex-Soviet Union Countries
      3 Europe                      8 Asia
      4 Europe                      9 Mideast
      5 South America and Mexico

   If a similar method is used, I would recommend assigning 0,1,10 and
   11 to North America, 8 and 12 to Asia, and leaving 13 through 15 for
   other areas as needed.  Note that this would simply make some routing
   choices easier, it is not precisely necessary that this be done,
   since currently routing is generally done using the shortest path to
   a site and IP numbers don't really relate to any specific address
   anywhere in the world.

   The number form of a class F, G, H or K address could still be listed
   in the standard form n.n.n.n, as long as it is not assumed that the
   4th chunk number alone identifies a local address and that numbers
   with the same preceding 3 chunks do not necessarily belong to the
   same network.

Summary

   In order to make the address space available, even if the method to
   implement this feature is not presently available, it is suggested
   that Class F, G, H, and K address space should be taken out of Class
   C space and reserved for the purpose of allowing smaller-sized
   networks so that this feature may be made available.  Since Class C
   addresses currently are only using the equivalent of one Class A
   number anyway, this should not cause a problem.

Notes

   [1] Common practice dictates that neither an address 0 nor 255 should
       be used in any "dotted" address.

   [2] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, RFC 1340,
       USC/Information Sciences Institute, July 1992.

   [3] To prevent confusion, no class "I" or "J" address was created by
       this memo.

   [4] It is expected that if the higher part of the network address
       occupying the 4-bits to the left of the Class F address are
       neither 0 nor 15, that a class F site could have 16 machines.  If
       the 4-bits to the left are all 0, the Class F site must not use
       number 0.  If the four bits are all 1, the site must not use
       number 15.




Robinson                                                        [Page 6]

RFC 1375              New Classes of IP Addresses           October 1992


   [5] It may be that Class H numbers are more appropriate for classes
       of addresses that will not have as high a demand for access via
       Internet addresses such as facsimile machines and pagers.  (The
       end digit could be used to determine class of service, i.e., 0
       for tone only, 1 and 2 for numeric only, 3 4 and 5 for
       alphanumeric, and 6 and 7 for facsimile machines.  Or some
       combination of these according to the demand.  Remember,
       Internet won't always be just text messages and file transfers;
       we may eventually see things like voice telephone calls or voice
       data being placed to an Internet address just like calls made
       via the telephone system.  This would require a whole change in
       the way things are done, but it's always best to look at the
       future.

   [6] It is suggested that addresses in this range not be assigned
       where the 7 bits to the left of the local number are all the
       same (all 0 or all 1), to allow all Class K addresses to have
       two local addresses.

   [7] Different things can be done with different capabilities.  One
       thought was to set up some group of numbers and use them to
       indicate systems which are "gateway" systems, i.e., the top set
       of numbers in Class K could indicate that subnets are required
       after those numbers, similar to the use of an extension number on
       the switchboard of a large organization.   Another possibility is
       to assign some of the numbers to specific classes of devices,
       such as number-only pagers and electronic display devices.

Security Considerations

   Security issues are not discussed in this memo.

Author's Address

   Paul Robinson
   Tansin A. Darcos & Company
   8604 Second Avenue #104
   Silver Spring, MD 20910 USA

   Phone: [phone]
   Telex:   6505066432MCI UW
   E-mail:  [e-mail]









Robinson                                                        [Page 7]