Re: [Idr] new ID on expansion of private use ASN range

[David Farmer <[e-mail]>]

On 7/3/12 13:54 CDT, Christopher Morrow wrote:
> On Tue, Jul 3, 2012 at 10:16 AM, Jon Mitchell <[e-mail]> wrote:
>> that I can walk in and request 10K+ ASNs with minimal justification and
>> low cost.  I don't see much value in increasing the administrative
>
> I would bet that if you were a large enterprise WAN like, say: "the
> Limited" (clothing store) that has +1.5 endsites, you could say to
> ARIN (for instance): "Hi, I have 1.5k endsites, all connected over a
> third-party WAN, we use BGP and have unique routing policies for each
> site, can I have 1.5k TODAY and since I plan to expand 500 sites this
> year 1k tomorrow" you would probably get that allocated, if you can
> deal with 4-byte.

So Chris, why does clothing store with 1.5k endsites want those ASNs 
publicly registered.  I tend toward why not, but they frequently seem to 
not want them publicly registered.  They clam it has something to do 
with security.  I don't buy it, but on the other had it is their network.

A lot of enterprise networks are starting to use BGP internally, but 
they seems to only want to deal with eBGP and no iBGP peerings or only 
very limited iBGP.  So they give every router or pair of site routers 
its own Private ASN.  I seen some with fairly elaborate routing policy, 
that would qualify as unique routing policy.  But many don't they just 
used Private ASN to avoid iBGP, without any unique routing policy.

So, currently Public ASN must be justified by unique routing policy, I 
believe this essentially comes from RFC 1930, this is the guidance from 
the IETF that the RIRs are using.  Actually most RIR also currently 
require multi-homing to justify an ASN as well. However, this is 
primarily attributed to scarcity of 2-byte ASNs, but could probably go 
away now that we have 4-byte ASNs.

But using an ASN so you don't have to deal with iBGP isn't justified by 
the unique routing policy criteria of RFC 1930.  If we don't think a 
unique routing policy is necessary any longer then maybe the IETF should 
give that guidance to the RIRs.

Realistically, even in your example of the large clothing store chain, 
I'll bet you there are not multiple unique routing policies involved, 
its because they want eBGP going to each of the endsites. Right or 
wrong, lots of people use private ASNs so that most if not all of their 
peerings are eBGP and not iBGP.



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