EUROPEAN AUTONOMOUS SYSTEM NUMBER
APPLICATION FORM & SUPPORTING NOTES
Document-ID: ripe-91.txt
Expiry Date: 28 February 1994
To whom it may concern.
Thank you for your request for an Autonomous System (AS)
number. The documentation below consists of two sections :
the first section refers to SUPPORTING NOTES which give a
definition and description of what an Autonomous System is,
together with a description of when an AS number is needed
and necessary. It is important that you read this section
carefully.
The second section, the AS NUMBER TEMPLATE is the actual
template that must be completed and returned to the RIPE
Network Coordination Centre (NCC). The template is divided
into two parts:
Part A - Administrative Details
Part B - Technical Details
You must complete part A in full. This is Mandatory. Part
B should also be filled in, but at the time of application
you may not know all the technical details. You can still
get an AS number without completing Part B, but you are
urged to submit the information as soon as possible.
Please ensure that you read all the information below care-
fully before submitting your application for an AS number.
For more detailed explanations please refer to the paper
"Representation of IP Routing Policies in the RIPE Database"
RIPE document ID: ripe-081.
If you have any queries, please do not hesitate to con-
tact the RIPE NCC who will be able to advise you. Our con-
tact details are given below:
RIPE NCC email: hostmaster@ripe.net
Kruislaan 409 tel: +31 20 592 5065
1098 SJ Amsterdam fax: +31 20 592 5090
The Netherlands
Yours sincerely.
hostmaster@ripe.net
RIPE Network Coordination Centre
September 3, 1993
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SUPPORTING NOTES for AUTONOMOUS SYSTEM (AS) NUMBER REQUESTS
Please read the information below carefully. It is impor-
tant that you read this before completing the template in
the following section as it contains essential definitions.
What is an Autonomous System ?
An Autonomous System (AS) is a group of IP networks run by
one or more network operators which has a single and clearly
defined routing policy.
An AS has a unique number associated with it which is used
in both the exchange of exterior routing information (i.e.
network reachability information between ASes) and as an
identifier of the AS itself. Exterior routing protocols such
as BGP and EGP are used to exchange routing information
between ASes.
In routing terms an AS will normally use one or more inte-
rior gateway protocols when exchanging network information
within its own AS.
The term AS is often confused or even misused as a con-
venient way of grouping together a set of networks which
belong under the same administrative umbrella even if within
that group of networks there are various different routing
policies. ASes can strictly have only one single routing
policy.
On the other hand, the creation of an AS should be done in a
conscious and well coordinated manner to avoid creating ASes
for the sake of it, perhaps resulting in the worst case
scenario of one AS per IP network number. This may mean that
by applying the general rules for the creation and alloca-
tion of an AS below, some re-engineering may be needed. How-
ever, this may be the only way to actually implement a
desired routing policy anyway.
How can I be sure I need an AS number ?
o Creation of an AS is only required when exchanging
routing information with other ASes. Some router imple-
mentations make use of an AS number as a form of tag-
ging to identify the routing process. However, it
should be noted that this tag does not need to be
unique unless routing information is indeed exchanged
with other ASes.
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o An IP network number can and must only belong to one
AS. This is a direct consequence of the fact that at
each point in the Internet there can only be exactly
one routing policy for traffic destined to each net-
work. In the case of the IP network which is used in
neighbor peering between two ASes, say at the border
between two ASes, a conscious decision must be made as
to which AS this IP network number actually resides in.
o For a simple case of customer networks connected to a
single service provider, the IP network should be a
member of the service provider's AS. In terms of rout-
ing policy the IP network has exactly the same policy
as the service provider and there is no need to make
any distinction in routing information. This idea may
at first seem slightly alien to some, but it highlights
the clear distinction in the use of the AS number as a
representation of routing policy as opposed to some
form of administrative use.
o If a network operator connects to more than one AS with
different routing policies then they need to create
their own AS. In the case of multi-homed customer net-
works connected to two service providers there are at
least two different routing policies to a given custo-
mer network. At this point the customer networks will
be part of a single AS and this AS would be distinct
from either of the service providers ASes. This allows
the customer the ability of having a different
representation of policy and preference to the dif-
ferent service providers. This is the ONLY case where a
network operator should create its own AS number.
o As a general rule one should always try to populate the
AS with as many IP networks as possible, providing all
IP networks conform to the same routing policy.
Each AS is represented in the RIPE database by an AS object.
The AS object stores descriptive, administrative and contact
information about the AS as well as the technical informa-
tion relating to the routing policies of the AS in relation
to all neighboring ASes.
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Example of a completed allocated AS number template which contains
information which is stored in the RIPE Network Management Database.
aut-num: AS1104
descr: NIKHEF-H Autonomous system
tech-c: Rob Blokzijl
admin-c: Eric Wassenaar
source: RIPE
changed: k13@nikhef.nl 920713
changed: ripe-dbm@ripe.net 920910
as-in: AS1213 100 AS1213
as-in: AS1913 100 AS1913
as-in: AS1755 150 ANY
as-out: AS1213 ANY
as-out: AS1913 ANY
as-out: AS1755 AS1104 AS1913 AS1213
guardian: as-guardian@nikhef.nl
This example contains Part B - technical details "routing
policy" information which it is not strictly necessary to
supply in the initial application for an AS number, but
which you are strongly urged to complete in the future when
you know your "routing policy". This is especially important
if you intend to connect to the Global Internet at some
stage in the future.
It is important to note that if you decide to send in your
"routing policy" later on, then you MUST accompany it with
the full administrative information. Otherwise we will not
know to which autonomous system and to which organisation
the routing information applies!
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Part A - Administrative Details
ADMINISTRATIVE TEMPLATE
aut-num:
How many AS numbers do you require?
Format: Please complete with a number
Example:
aut-num: 1
descr:
A short description of the Autonomous system.
Format: free text, multiple lines in sequence allowed
as in example below
Example:
descr: NIKHEF section H
descr: Science Park Watergraafsmeer
descr: Amsterdam
tech-c:
Name or NIC-handle of technical contact person. This
is someone to be contacted for technical problems such
as misconfiguration, etc.
Format: <firstname> <initials> <lastname>, multiple
lines.
Example:
tech-c: John E. Doe
admin-c:
Name or NIC-handle of administrative contact person.
This is most likely to be the same name as the guardian
but it is not mandatory for it to be.
Format: <firstname> <initials> <lastname>, multiple
lines.
Example:
admin-c: Joe T. Bloggs
changed:
Email address of the person who is completing the
template, followed by the current date. If you do not
have email connectivity please leave blank and we
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will complete it.
Format: as shown below.
Example:
changed: johndoe@terabit.nl 930225
source: RIPE
Source of the information. It will always be
RIPE. This is information which is always required in
the database, so it has been added already.
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Part B - Technical Details
You may not at the time of applying for your AS number know
the technical details requested below. Therefore we do not
make completing this section mandatory. However, you are
*strongly urged* to complete this section as soon as possi-
ble once you know your routing policy and return your
amended template to <hostmaster@ripe.net> for inclusion in
the RIPE Network Management Database. Please note, that if
you send this section in later, you must send it in accom-
panied by a completed Section A - Administrative Details
otherwise we will not know to which AS or which organisation
the routing policy information applies.
TECHNICAL TEMPLATE
as-in:
A description of accepted routing information from
neighboring ASes.
Format: <aut-num> <cost> <routing policy expression>,
on multiple lines. where:
<aut-num> refers to your neighboring AS.
<cost> is a positive integer used to express a relative
cost of routes learned. The lower the cost the more
preferred the route.
<routing policy expression> can take the following for-
mats:
1. A list of one or more ASes.
Example:
as-in: AS1103 100 AS1103
as-in: AS786 105 AS1103
as-in: AS786 10 AS786
as-in: AS1755 110 AS1103 AS786
2. A set of KEYWORDS. The following keywords are
currently defined.
Example:
ANY - this means anything the neighbor AS knows.
RIPE-DB - any network currently in the RIPE database.
LOCAL - any network in the RIPE database which is part
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of the community LOCAL (i.e. no connectivity outside
its own organisation).
3. A logical expression of either 1 or 2 above. The
current logical operators are defined as:
AND
OR
NOT
Rules are grouped together using parenthesis i.e "("
and ")".
Example:
as-in: AS1755 100 RIPE-DB AND NOT (LOCAL AS513)
as-in: AS1755 150 DEFAULT
as-out:
A description of generated routing information sent to
other AS peers.
Format:<aut-num> <routing policy expression>, multiple
lines. Where:
<aut-num> refers to your AS neighbor.
<routing policy expression> is explained in the as-in
definition
Example:
as-out: AS1104 AS978
as-out: AS1755 ANY
as-out: AS786 RIPE-DB AND NOT (AS978 LOCAL)
default:
An indication of how default routing is done.
Format: <aut-num> <relative cost>, multiple lines.
Where:
<aut-num> The AS peer you will default route to.
<relative cost> The relative cost is a positive integer
use to express a preference for default. There is no
relationship to the cost used in the "as-in" tag. The
lower the cost indicates which AS peer is more pre-
ferred for default.
Example:
default: AS1755 10
default: AS786 5
guardian:
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Mailbox address of the guardian of the Autonomous Sys-
tem
Format: <email-address>, single line. This should be in
RFC822 format wherever possible.
Example:
guardian: as1104-guardian@nikhef.nl
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EUROPEAN AUTONOMOUS SYSTEM NUMBER
APPLICATION FORM
Part A - ADMINISTRATIVE TEMPLATE
aut-num:
descr:
tech-c:
admin-c:
source: RIPE
changed:
Part B - TECHNICAL TEMPLATE
as-in:
as-in:
as-in:
as-out:
as-out:
as-out:
guardian:
Please return this completed template to
<hostmaster@ripe.net>. You can also send it by fax. Mark
your fax for the attention of RIPE NCC HOSTMASTER. Our fax
number is +31 20 592 5090.
September 3, 1993