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                          Temporary Special Guidelines for

                             Allocation and Assignment

                            of former class A addresses.

                                   Mirjam Kuehne
                                 Daniel Karrenberg
                                 Document: ripe-155


                                   ABSTRACT


                          In order to encourage a transition to
                     the classless use of former class A
                     address space, the RIPE NCC proposes a
                     temporary test period during which Local
                     Registries and their customers can start
                     to use parts of these addresses. Addi-
                     tional allocation and assignment proce-
                     dures will apply during this test period.



    Background

                Before the introduction of classless inter-domain
                routing CIDR [RFC1519], the unicast IP address space
                was divided into three ranges called A, B and C each
                assotiated with a routing prefix length of 8, 16 and
                24 bits respectively.  In this context IP addresses
                are often called class A, B or C addresses depending
                on the range:

                0.0.0.0   - 127.255.255.255 used to be called class
                A addresses

                128.0.0.0 - 191.255.255.255 used to be called class
                B addresses

                192.0.0.0 - 223.255.255.255 used to be called class
                C addresses

                There were two more ranges reserved initially.  For
                the understanding of this document they are irrele-
                vant.

                With CIDR, the prefix length information is carried
                in the routing protocols and it is technically
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                insignificant which particular range an address
                belongs to.

                However, for the readability of this document we
                will use the historic terms class A, class B and
                class C.

                As long as classful routing protocols or obsolete
                TCP/IP host implementations are being used, the
                class (as implied by the particular range) of the
                address can become significant because either it
                determines prefix length in routing or other assump-
                tions are being made from the class of the address.
                Classful software can be configured to work properly
                by using subnetting [RFC950] or basing configura-
                tions on the prefix length implied by the address
                class.

                The Internet registries, regional and local, have
                been assigning addresses out of the class C range
                for the last years because this was believed to
                cause the least problems with obsolete classful
                software on the perimeter of the Internet.

                However there is only a limited amount of unallo-
                cated class C address space available.  More than
                50% of the class C address space is allocated and
                some parts of the remaining ranges are reserved by
                IANA.  Currently the largest amount of unallocated
                addresses is in class A space. Therefore regional
                Internet registries will at some point have to use
                allocations from this range.

                In April 1995 an experiment started to find out if
                classless use of class A addresses would create any
                significant problems with respect to routing. The
                aim of this experiment is described in RFC1797.  The
                experiment ran for 6 months and was considered a
                success.The results of are described in RFC1879
                including possible problems and solutions.


    RIPE Community Initiative

                To promote the use of classless addressing the RIPE
                NCC has taken the initiative to give local IRs in
                its service region a choice of allocations either
                from class C or class A space.

                At the 26th RIPE meeting held in Amsterdam in Jan-
                uary 1997 the RIPE community welcomed this initia-
                tive and expressed their interest in assigning this
                type of addresses to their customers.  There was
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                consensus that in order to encourage usage of class
                A address space, additional allocation and assign-
                ment guidelines should be implemented for a fixed
                period of time. The RIPE NCC circulated a proposal
                in March 1997.  The feedback is incorporated in this
                document.

                The following sections will describe the special
                allocation procedures the RIPE NCC proposes. These
                have been approved by IANA and coordinated with the
                other regional Internet registries.


    Special Allocation Rules

                From April 1997 until December 1997 special guide-
                lines will apply to the allocation and assignment of
                class A address space.  These guidelines are addi-
                tions to the regular procedures [currently
                ripe-140].

                During this time any organisation established as
                Local Internet Registry (LIR) in the service region
                of the RIPE NCC may request an additional allocation
                of class A address space.

                This means that for a limited amount of time any LIR
                can hold two allocations of the same size: one from
                class C address space (currently 193.0.0.0/8,
                194.0.0.0/8, 195.0.0.0/8) and one from class A
                (62.0.0.0/8).

                In order to limit the adverse effect of these spe-
                cial allocations on routing table growth, global
                routing annnouncements for this address space should
                be kept at an absolute minimum.  Ideally each allo-
                cation will be announced via just one prefix.  Addi-
                tional prefixes should only be announced globally if
                this is technically necessary.

                Once a LIR has obtained an allocation from class A
                space in addition to an existing allocation from
                class C space the following rules apply:


                  1. If the address space from a class A allocation
                     is entirely assigned, another class A alloca-
                     tion can be requested.


                  2. If the address space from a class C allocation
                     is entirely assigned, another class A or class
                     C allocation can be requested.
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                This means that a LIR can have two class A alloca-
                tions or one allocation of each class but never two
                class C allocations.

                After the expiration of the special period, the
                usual allocation policies will apply, i.e. every LIR
                can only hold one open allocation of a maximum of a
                /16 at a time. This means that first all allocations
                the LIR has at this point in time must be finished
                before additional address space can be allocated.

                If the LIR has at this point decided that it will
                not continue assigning from class A address space it
                has the option of returning the whole range of class
                A addresses allocated to it.  It can then request an
                additional class C allocation once the previously
                allocated class C addresses are entirely assigned.


    Special Assignment Guidelines

                In order to motivate not only LIRs to use class A
                address space, but also end-users to use class A
                address space in their networks special assignment
                policies apply until the end of the special period.


                  1. A temporary assignment from class A space in
                     addition to an already existing assignment can
                     be made without detailed documentation so that
                     the end-user can experiment with these
                     addresses. If the end-user does not have an
                     assignment yet, the assignment will have to be
                     made according to the normal procedures (cur-
                     rently described in ripe-140).


                  2. This additional assignment can have up to the
                     same size of the total previously assigned
                     address space but not more than a /19.


                  3. The class A address space must be returned by
                     the end-user to the appropriate Internet reg-
                     istry 6 months after the assignment or the
                     usage of the addresses must be documented prop-
                     erly according to normal assignment rules [cur-
                     rently ripe-140].


                     The duration of a temporary assignement can be
                     agreed with the end-user and/or specified by
                     the LIR.
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                     The validity of the assignment expires in any
                     case at the end of 1997.


                     If the LIR decides to continue to assign
                     addresses from a class A space allocation, then
                     the assignments have to be converted to regular
                     assignments.  Otherwise the entire allocation
                     must be returned to the RIPE NCC.


                     The conversion to a regular assignment involves
                     completing and filing documentation according
                     to the "European IP Address Space Request Form"
                     [currently ripe-141] and adjusting the size of
                     the assignment if necessary.  The documentation
                     does not need to be submitted to the RIPE NCC.
                     However, the RIPE NCC may decide to review it
                     at any time.
                     Note: As per these rules address space assign-
                     ments can be justified by returning an equiva-
                     lent amount of addresses as well as by docu-
                     menting new use.


                  4. The LIR is obliged to clearly inform the
                     address space user about the special rules that
                     apply to the additional assignment before it is
                     made.  LIRs are encouraged to advise users to
                     plan ahead.


                  5. All assignments no matter from which allocation
                     must be registered in the RIPE database also
                     during the special period.


    Conclusion

                In order to promote classless addressing and to
                address the shortage of class C address space, the
                RIPE NCC proposes to give all LIRs in its service
                region the chance to prepare for the final transi-
                tion to classless addressing and the use of class A
                address space.

                This document proposes to create special guidelines
                for addresses from class A space until the end of
                1997. After this period it is expected that more
                registries are prepared to assign class A address
                space to their customers as as well as to their own
                networks.

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