APNIC-0xx ========= Special Guidelines for Allocation and Assignment for Network 61 Issued: November 26, 1997 Expires: N/A ABSTRACT In order to encourage a transition to the classless use of former class A address space, APNIC has initiated a temporary test period during which APNIC members and their customers can make use of subnets of class A addresses. Additional allocation and assignment procedures described in this document 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 class A, B, and C each associated 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 irrelevant. With CIDR, the prefix length information is carried in the routing protocols and it is technically insignificant which particular range an address belongs to. For the readability of this document however, 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 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 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 unallocated 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 this experiment are described in RFC1879 including possible problems and solutions. APNIC Network 61 Experiment To promote the use of classless addressing the APNIC has taken the initiative to give members in its service region a choice of allocations either from class C or class A space. At the 3rd APNIC meeting held in Kuala Lumpur in June, 1997 the APNIC community welcomed this initiative and expressed their interest in assigning class A addresses to their customers. There was consensus that in order to encourage usage of class A address space, additional allocation and assignment guidelines should be implemented for a fixed period of time. The following sections will describe the special allocation procedures APNIC utilizes for the Network 61 experiment. These procedures have been approved by the IANA and are in use in a similar experiment within the RIPE-NCC community. Special Allocation Rules From the issuance of this document until December 31, 1999, special guidelines will apply to the allocation and assignment of class A address space. These guidelines are additions to the regular allocation procedures. During this time any organisation established as an APNIC member may request an additional allocation of class A address space. Thus, for a limited amount of time any ISP can hold two allocations of the same size: one from class C address space (currently 202.0.0.0/7 and 210.0.0.0/7) and one from the APNIC class A space (61.0.0.0/8). In order to limit the adverse effect of these special allocations on routing table growth, global routing annnouncements for this address space should be kept to an absolute minimum. Ideally each allocation will be announced via just one prefix. Additional prefixes should only be announced globally if this is technically absolutely necessary. Once an ISP 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 allocation 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. This means that an ISP can have two class A allocations 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 ISP can only hold one open allocation at a time. This means that first all allocations the ISP has at the point in time of the request must be 75% consumed before additional address space can be allocated. If the ISP has at the time of the request 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 ISPs but also end users to use class A address space in their networks, special assignment policies apply until the end of the experiment period (December 31, 1999): 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. 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 registry 6 months after the assignment or the usage of the addresses must be documented properly according to normal assignment rules. The duration of a temporary assignement can be agreed with the end-user and/or specified by the ISP. The validity of the assignment expires in any case at end of December 31, 1999. If the ISP 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 APNIC The conversion to a regular assignment involves completing and filing documentation according to the "ISP IP Address Request Form" and adjusting the size of the assignment if necessary. The documentation does not need to be submitted to APNIC. However, APNIC may decide to review it at any time. Note: As per these rules address space assignments can be justified by returning an equivalent amount of addresses as well as by documenting new use. 4. The ISP is obliged to clearly inform the address space user about the special rules that apply to the additional assignment before it is made. ISPs are encouraged to advise users to plan ahead. 5. All assignments no matter from which allocation must be registered in the APNIC database also during the special period. Conclusion In order to promote classless addressing and to make more efficient use of the remaining unallocated address space, APNIC has proposed to give members the chance to prepare for the final transition 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 December, 1999. After this period it is expected that more ISPs will be prepared to assign class A address space to their customers as as well as to their own networks.