Dear SIG members
The proposal '32-bit ASNs for documentation purposes' has been sent to
the Policy SIG for review. It will be presented at the Policy SIG at
APNIC 26 in Christchurch, New Zealand, 25-29 August 2008.
The proposal's history can be found at:
We invite you to review and comment on the proposal on the mailing list
before the meeting.
The comment period on the mailing list before an APNIC meeting is an
important part of the policy development process. We encourage you to
express your views on the proposal:
- Do you support or oppose this proposal?
- Does this proposal solve a problem you are experiencing? If so,
tell the community about your situation.
- Do you see any disadvantages in this proposal?
- Is there anything in the proposal that is not clear?
- What changes could be made to this proposal to make it more
randy and jian
prop-061-v001: 32-bit ASNs for documentation purposes
Author: Philip Smith
pfs at cisco dot com
Gaurab Raj Upadhaya
gaurab at lahai dot com
Date: 14 July 2008
This document discusses the requirement to reserve 32-bit ASNs for the
sole purpose of assisting the creation of Internet related
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
1. Using private address space and/or private AS space
RFC 1918  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
The AS range 64512 to 65534  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  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 22.214.171.124, 126.96.36.199, 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
- 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
- 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).
- 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
- 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
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.
 RFC 1918, Address Allocation for Private Internets
 Autonomous System (AS) Numbers,
 RFC 3849, IPv6 Address Prefix Reserved for Documentation
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