Autonomous System (AS) Number Assignment Policies and Procedures
Mirjam Kuehne
Nurani Nimpuno
Sabrina Wilmot
Document ID: ripe-263
Date: 22 January 2003
Obsoletes: ripe-185, ripe-245
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Description
This document provides a description of Autonomous System Numbers,
their assignment procedures and guidelines on how to obtain them in
RIPE NCC service region.
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Table of Contents
* 1.0 AS Number Assignment Policies and Procedures
* 1.1 Assignments for Internetworking Experiments
* 1.2 Defining the Experiment
* 1.3 Publication
* 1.4 Non-commercial Basis
* 1.5 Period of Temporary Resource Registration
* 1.6 Registration
* 1.7 Requesting an AS Number
* 1.8 Returning an AS Number
1.0 AS Number Assignment Policies and Procedures
An Autonomous System (AS) is a group of IP networks run by one or
more network operators with a single, clearly defined routing
policy. When exchanging exterior routing information each AS is
identified by a unique number. Exterior routing protocols such as
BGP, described in RFC 1771, "A Border Gateway Protocol 4 (BGP-4)",
are used to exchange routing information between Autonomous
Systems. More information on RFC 1771 can be found at:
ftp://ftp.ripe.net/rfc/rfc1771.txt
An AS will normally use some interior gateway protocol to exchange
routing information on its internal networks.
In order to help decrease global routing complexity, a new AS
Number should be used only if a new external routing policy is
required. Sharing an AS Number among a set of networks that do not
fall under the same organisational umbrella is possible but will
sometimes require extra co-ordination among the various network
administrators. (In some cases, some level of network
re-engineering may be needed.) This may be the only way to
implement the desired routing policy. For more information please
see RFC 1930, "Guidelines for creation, selection, and registration
of an Autonomous System (AS)" found at:
ftp://ftp.ripe.net/rfc/rfc1930.txt
Current guidelines require a network to be multi-homed for an AS
Number to be assigned. Requests must show the routing policy of the
Autonomous System. The policy is defined in the following
attributes as part of the aut-num object: multiple fields of
"import:" (describing accepted routing information from
neighbouring ASs.); multiple fields of "export:" (describing
generated routing information sent to peers); one or more
(optional) fields of "default:" (indicating how default routing is
done).
1.1 Assignments for Internetworking Experiments
Organisations often require deployment tests for new Internet
services and technologies. These require numbering resources for
the duration of the test.
The policy goal of resource conservation is of reduced importance
when resources are issued on a temporary basis.
1.2 Defining the Experiment
An organisation receiving numbering resources must document the
experiment. This may be in the form of a current IETF Experimental
RFC (see RFC 2026, Sec. 4.2.1) or an "experiment proposal"
detailing the resources required and the activities to be carried
out.
A single AS Number will be assigned. Where the experiment requires
a variation to this rule it should be noted in the resource request
forms sent to the RIPE NCC.
1.3 Publication
The experiment proposal must be made public (e.g. published on web
site), upon registration of the resources by the RIPE
NCC. Following the conclusion of the experiment the results must be
published free of charge and free from disclosure constraints.
1.4 Non-commercial Basis
Resources issued for an experiment must not be used for commercial
purposes.
1.5 Period of the Temporary Resource Registration
The resources will be issued on a temporary basis for a period of
one year. Renewal of the resource's registration is possible on
receipt of a new request that details any continuation of the
experiment during the extended period.
The resources issued cannot be used for a commercial service
following the conclusion of the experiment.
1.6 Registration
The RIPE NCC will register the resources issued in the RIPE Whois
Database.
1.7. Requesting an AS Number
The RIPE NCC assigns AS Numbers for Autonomous Systems located in
the RIPE NCC service region and only accepts requests for AS
Numbers from LIRs. LIRs may request AS Numbers on behalf of other
organisations.
The request must be made by a Local Internet Registry (LIR) using
the appropriate request form. To obtain an AS Number, the RIPE NCC
provides a form containing two database templates:
- aut-num (autonomous system number) template,
- mntner (maintainer) template.
All of the information requested in the form is required. The RIPE
NCC may also ask for additional information in order to understand
the planned routing policy and to decide if an AS Number is needed.
The information provided in the templates will be entered into the
RIPE Whois Database and is publicly accessible. For more
information on Database templates, please refer to:
http://www.ripe.net/perl/whois?-v+aut-num
http://www.ripe.net/perl/whois?-v+mntner
A completed form should be sent to the RIPE NCC Hostmaster mailbox,
<hostmaster@ripe.net>. After evaluating the requests, the RIPE NCC
will enter all relevant information in the RIPE Database and will
notify the LIR of the assignment.
The AS Number request form and supporting notes can be found at:
http://www.ripe.net/ripe/docs/internet-registries.html#request
1.8. Returning an AS Number
If an organisation has an AS Number that is no longer in use, it
can be returned to the public pool of AS Numbers by sending a
message to <hostmaster@ripe.net>. It can then be reassigned to
another Autonomous System by the RIPE NCC.