[arin-ppml] Recommended Draft Policy ARIN-2021-3: Private AS Number and Unique Routing Policy Clarifications

John Santos john at egh.com
Tue Mar 22 16:16:11 EDT 2022


We are doing exactly that: exchanging routing information with one of our 
customers using BGP routing over a private network (multiple, redundant VPN 
circuits using different ISPs at our end and two different geographically 
dispersed sites at our customer's end.)  We are using one of the private ASNs, 
which works fine for our purposes, but if multiple customers wanted to do the 
same thing, we might need to avoid colliding the private ASNs to prevent 
route-through to our customers' other vendors or from one customer to another.

Only one customer has dynamic networking, with multiple possible routes; all our 
other customers are configured with static routing.

So right now we don't need an assigned ASN, but we might someday.

There is no "Upstream" involved. the networks are peer-to-peer.  I think this is
(or would be if there were more peers) an example of what Andrew is describing.

I think Owen is saying the two items (first and third of the reasons to justify 
a public ASN) are equivalent and the third is fewer words and easier to 
understand.  The 1st reason doesn't apply if there is no Upstream, so they 
aren't equivalent.  However, I'm not sure the first reason is a proper subset of 
the third.  (If it were, then the first reason would be redundant.)

Don't know if I'm clarifying the question or muddying the waters.

-- John

On 3/22/2022 2:15 PM, Andrew Dul wrote:
> "To use an AS Number to interconnect with other Autonomous Systems." was 
> intended to apply to situations where a public ASN number was desired for 
> exchanging routes between organizations but where the concept of an "upstream 
> provider" wasn't appropriate.  An example might be if an there were two or more 
> organizations which are exchanging routes, but the organizations wanted unique 
> AS Numbers to ensure there are not any AS number collisions.
> 
> Hope this helps,
> Andrew
> 
> On 3/22/2022 10:46 AM, Owen DeLong via ARIN-PPML wrote:
>> Can someone clarify for me the meaningful difference between:
>>
>> To originate announcement of IP Number Resources via an accepted protocol 
>> (such as Border Gateway Protocol) from an AS Number different than that of its 
>> upstream provider;
>>
>> and
>>
>> To use an AS Number to interconnect with other Autonomous Systems.
>>
>>>>
>> It seems to me that anything defined by the first sentence would be 
>> encompassed in the second.
>>
>> Further, while I admit my imagination may be limited here, I am unable to 
>> imagine a useful implementation of the second sentence that would not also 
>> conform to the first and would require a unique non-private ASN.
>>
>> While I can see useful instances for receive-only (non-originating) BGP 
>> sessions, such as route servers, etc., I’m hard pressed to see why they would 
>> need a unique public ASN. Even if they do, a useful route server is, by 
>> definition, multi-homed.
>>
>> Not necessarily opposed to the policy as written, but think that it’s a lot of 
>> extra words with little actual value in terms of clarity and perhaps even 
>> muddying the waters a bit.
>>
>> Owen
>>
>>
>>> On Mar 22, 2022, at 09:04, ARIN <info at arin.net> wrote:
>>>
>>> On 17 March 2022, the ARIN Advisory Council (AC) advanced the following Draft 
>>> Policy to Recommended Draft Policy status:
>>>
>>> * ARIN-2021-3: Private AS Number and Unique Routing Policy Clarifications
>>>
>>> The text of the Recommended Draft Policy is below, and may also be found at:
>>>
>>> https://www.arin.net/participate/policy/drafts/2021_3/
>>>
>>> You are encouraged to discuss all Recommended Draft Policies on PPML prior to 
>>> their presentation at the next ARIN Public Policy Consultation (PPC). PPML 
>>> and PPC discussions are invaluable to the AC when determining community 
>>> consensus.
>>>
>>> The PDP can be found at:
>>>
>>> https://www.arin.net/participate/policy/pdp/
>>>
>>> Draft Policies and Proposals under discussion can be found at:
>>>
>>> https://www.arin.net/participate/policy/drafts/
>>>
>>> Regards,
>>>
>>> Sean Hopkins
>>> Senior Policy Analyst
>>> American Registry for Internet Numbers
>>>
>>> Recommended Draft Policy ARIN-2021-3: Private AS Number and Unique Routing 
>>> Policy Clarifications
>>>
>>> AC Assessment of Conformance with thePrinciples of Internet Number Resource 
>>> Policy 
>>> <http://www.arin.net/participate/policy/pdp/#4-principles-of-internet-number-resource-policy>:
>>> Recommended Draft Policy ARIN-2021-3 conforms to the principles of the ARIN 
>>> Policy Development Process as follows:
>>> - By providing greater clarity concerning when a requesting organization 
>>> qualifies for AS Numbers, it promotes fair and impartial number resource 
>>> administration;
>>> - It is technically sounds because it clarifies the technical requirements 
>>> for obtaining AS Numbers (i.e., the need to interconnect with other 
>>> organizations’ Autonomous Systems, what constitutes a “unique routing 
>>> policy”, and the need to have a network plan); and
>>> - Community support has been demonstrated throughout the process associated 
>>> with its development.
>>> Problem Statement:
>>> At ARIN 47, staff identified three points of potential confusion with current 
>>> text in NRPM Section 5: AS Numbers.
>>> “Sites that do not require a unique AS Number should use one or more of the 
>>> AS Numbers reserved for private use.” Some customers are not aware that their 
>>> need for unique AS Numbers depends upon their need (or lack thereof) to 
>>> interconnect with other organizations’ Autonomous Systems.
>>> “In order to be assigned an AS Number, each requesting organization must 
>>> provide ARIN with verification that it has one of the following…A unique 
>>> routing policy (its policy differs from its border gateway peers)…A 
>>> multihomed site.” Few customers qualify for AS Numbers under the “unique 
>>> routing policy” requirement, because they don’t understand what “unique 
>>> routing policy” actually means in practice.
>>> “AS Numbers are issued based on current need. An organization should request 
>>> an AS Number only when it is already multihomed or will immediately become 
>>> multihomed.” All ARIN delegations are based on current needs, and some 
>>> customers aren’t aware they need network plans when they request AS Numbers. 
>>> Additionally, clarification that some organizations may have a unique need 
>>> for an AS Number outside of utilizing a unique routing policy, such as one 
>>> implemented using, for example, a protocol such as Border Gateway Protocol (BGP).
>>> Policy statement:
>>> In Section 5 -
>>> Replace
>>> “Sites that do not require a unique AS Number should use one or more of the 
>>> AS Numbers reserved for private use.”
>>> with
>>> “If a unique AS Number is not required for a given network design, one or 
>>> more of the AS Numbers reserved for private use should be utilized.”
>>> Replace
>>> “In order to be assigned an AS Number, each requesting organization must 
>>> provide ARIN with verification that it has one of the following
>>> A unique routing policy (its policy differs from its border gateway peers) 2. 
>>> A multihomed site”
>>> with
>>> “In order to be assigned an AS Number, each requesting organization must 
>>> provide ARIN with verification that it requires a unique routing policy, such 
>>> as a plan:
>>> To originate announcement of IP Number Resources via an accepted protocol 
>>> (such as Border Gateway Protocol) from an AS Number different than that of 
>>> its upstream provider;
>>> To multihome a site with one or more Autonomous Systems; or
>>> To use an AS Number to interconnect with other Autonomous Systems.”
>>> Replace
>>> “AS Numbers are issued based on current need. An organization should request 
>>> an AS Number only when it is already multihomed or will immediately become 
>>> multihomed.”
>>> with
>>> “AS Numbers are issued based on current need, as set out in this section 5.”
>>> Timetable for implementation: Immediate
>>> _______________________________________________
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>>
>>
>> _______________________________________________
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> 
> 
> 
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-- 
John Santos
Evans Griffiths & Hart, Inc.
781-861-0670 ext 539


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