Dear chair people and local registries, dear IANA, During the Local IR working group at the 26th RIPE Meeting in January in Amsterdam we learned that many local registries would be interested and prepared to assign addresses from former class A space. Because most registries have no experience with class A adddress space yet the RIPE NCC proposes to introduce new guidelines for a certain period of time. The proposal is attached below. Please send all comments, questions and suggestions you might have until the 17th March 1997 to me personally. We are planning to publish the proposal as a RIPE document after this date. Kind Regards, Mirjam Kuehne Manager Registration Services RIPE NCC ------- Temporary Special Class A Space Guidelines Kuehne, Karrenberg D R A F T ____________________________________________________ Temporary Special Guidelines for Allocation and Assignment of address space out of class A ranges. Mirjam Kuehne Daniel Karrenberg 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. With CIDR the prefix length informa- tion is carried in the routing protocols and it is technically insignificant which particular range an address belongs to. Whenever classful routing protocols or obsolete TCP/IP host implementations are being used the class of the address can become significant because either it determines prefix length in routing or other assumptions are being made from the class of the address. Classful software can be configured to work properly by using subnetting [RFC950] or basing configurations on the prefix length implied by the address class. The Internet registires have been assigning addresses out of the class C range for the last cou- ple of 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 of class A. Therefore regional Internet registries will at some point have to use allocations from class A space. In April 1995 an experiment started to find out if classless use of the former class A addresses (1.0.0.0 - 126.255.255.255) would create any signifi- cant problems wrt routing. The aim of this experiment ____________________________________________________ Page 1  Temporary Special Class A Space Guidelines Kuehne, Karrenberg D R A F T ____________________________________________________ is described in RFC1797. The experiment ran for 6 month 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 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 consensus that in order to encourage usage of class A address space, allocation and assignment guide- lines for this space should be temporarily relaxed if IANA and the other regional IRs agree to this. The RIPE NCC was asked to make a proposal. The following sections will describe the special allocation procedures the RIPE NCC proposes. 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 normal procedures [ripe-140]. During this time every orgnisation established as a LIR in the service reigion of he RIPE NCC may request an additional allocation of class A address space. This means for a limited amount of time each LIR can hold two allocations of the same size: one from class C address space (currently 195.0.0.0/8) and one from class A (to be allocated by IANA). 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 already existing allocation ____________________________________________________ Page 2  Temporary Special Class A Space Guidelines Kuehne, Karrenberg D R A F T ____________________________________________________ from class C space the following rules apply: 1. If the address space from the class A alloca- tion is entireley assigned, another class A allocation can be requested. 2. If the address space from the class C alloca- tion is entirely assigned, another class A or class C allocation can be requested. 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 apply, i.e. every LIR can only hold one free alocation 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 possibility to return the class A alloca- tion. It can then request an additional class C allocation once the previously allocated class C addresses are assigned entirely. 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 from class C address space can be made without detailed documentation so that the end-user can experiment with these addresses. 2. This additional assignment can have up to the same size of the total previously assigned address space but not more than a /19. ____________________________________________________ Page 3  Temporary Special Class A Space Guidelines Kuehne, Karrenberg D R A F T ____________________________________________________ 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 [ripe-141]. Note: As per these rules address space assign- ments can be justified by returning an equiva- lent ammount 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 wich allocation must be registerd in the RIPE database. 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 most registries are prepared to assign class A address space to their customers as as well as to their own networks. ____________________________________________________ Page 4