________________________________________________________________________ prop-061-v001: 32-bit ASNs for documentation purposes ________________________________________________________________________ Author: Philip Smith pfs@cisco.com Gaurab Raj Upadhaya gaurab@lahai.com Version: 1 Date: 14 July 2008 1. Introduction ---------------- This document discusses the requirement to reserve 32-bit ASNs for the sole purpose of assisting the creation of Internet related documentation. 2. Summary of current problem ------------------------------ For 32-bit ASNs, the AS space above 65535 (or 1.0 in "dot" notation) is either reserved for future use or allocated, with no portion of the space available for documentation purposes. Authors often need to include example address space and AS numbers when documenting the Internet and the configuration of equipment used in the operation of the Internet. Authors currently use Internet resources from a variety of sources. The following examples describe typical example usage of such Internet resource: 1. Using private address spacend/or private AS space RFC 1918 [1] address space is often used for documentation requiring the use of IPv4 address space. It's not ideal, but given that the addresses look like the rest of IPv4 address space, and that it is an ISP BCP to filter private addresses out of Internet announcements, its use protects against cut-and-paste accidents. The AS range 64512 to 65534 [2] is often used for documentation requiring the use of 16-bit AS numbers. Most ISPs automatically filter private ASNs out of the AS path as they announce them to the Internet, so the use of private ASNs for documentation is not normally a problem. 2. Resources reserved for documentation purposes RFC 3849 [3] describes an IPv6 address block which can be used exclusively for documentation purposes. 3. Using Internet resources from their employer. This is easy to do, and this resource is typical of that which is routed on the Internet. 4. Using Internet resources of a typical network on the Internet. Quite often the resources of the larger and more commonly known ISPs are used in examples. 5. Easy to remember address values and ASNs are used. Typical examples might be 1.1.1.1, 2.2.2.2, AS100, AS2.4 and so on. Quite often these resources are from existing allocations. 6. Resources from ranges unassigned/unallocated at the time the documentation is written have been used. For example, ASNs above 48000, or the network 222/8 address block have been used. There are two major problems with the last four options above: - Readers, especially those who are learning about the Internet, do tend to cut and paste the configuration examples onto running equipment. Quite often this lab equipment is connected to a live production network, causing confusion and disruption to the innocent network used in the example. The Internet today is a serious commercial entity with the vast majority of business participating in it attributing a serious portion of their annual revenue to business done over the net. Dealing with a denial of service attack caused by an innocent cut and paste by a student of the industry has in the past caused major revenue loss for some organisations this has the potential to reoccur in the future. - Using address and AS space which is unused at the time the documentation is written means that at some stage in the near future the examples can disrupt real live networks, as has just been discussed in the previous point. 3. Situation in other RIRs ---------------------------- The RIRs currently have no formal common policy for making a 32-bit ASN allocation exclusively for documentation purposes. 4. Details of the proposal ----------------------------- It is proposed that: 4.1 APNIC set aside a common block of 32-bit ASNs to be used solely for the purpose of documentation. 4.2 The 32-bit ASN block for documentation include four ASNs. This is sufficient for a small network topology to include either exclusive 32-bit ASN or a mixture of 16-bit or 32-bit ASNs for purposes of documenting relationships between ASNs. 5. Advantages and disadvantages of the proposal ------------------------------------------------- Advantages: - Authors of documentation and Internet books no longer have to use 32-bit ASNs which belong to their employer (and risk causing disruption to their employers business), or using 32-bit ASNs allocated to random organisations around the Internet (and risk causing disruption to a multitude of organisations). Disadvantages: - Acceptance of this proposal will mean that four 32-bit ASNs will be added to the non-routable ASN space of the Internet. The four 32-but ASNs will need to be added to the existing AS_PATH filter list used by all ISPs, in the same way that RFC 1918 and RFC 3849 address space should never appear on the public Internet. - Acceptance of this proposal could potentially make some people believe that this ASN block is effectively private ASN space as it is not routable. - If this proposal is rejected, authors will have to carry on with the practice highlighted in the Background section of this proposal, with the associated risks to the integrity of the commercial Internet. 6. Effect on APNIC members ---------------------------- This proposal has no direct effect on APNIC members. 7. Effect on NIRs ------------------- This proposal has no direct effect on NIRs. 8. References --------------- [1] RFC 1918, Address Allocation for Private Internets http://www.ietf.org/rfc/rfc1918.txt [2] Autonomous System (AS) Numbers, http://www.iana.org/assignments/as-numbers [3] RFC 3849, IPv6 Address Prefix Reserved for Documentation http://www.ietf.org/rfc/rfc3849.txt