Re: [Idr] new draft - reservation of two already reserved ASNs

[David Farmer <[e-mail]>]

On 5/20/13 08:02 , Jon Mitchell wrote:
>
> IDR -
>
> During the private asn draft process, several times it was recommended
> that proper documentation of the EXISTING reservations for 65535 and
> 4294967295 be done, so have posted a draft to try and rectify that.
> Wanted to get some initial feedback on this draft and add any
> additional reasoning the group has for these reservations before
> asking for WG acceptance.

At a minimum, we need to formally document the technical reservation of 
the numerically highest 16 and 32 bit ASNs as this draft does.

However, another approach would be to deal with these two ASNs as a 
protocol issue and require implementations of BGP to NOT originate or 
propagate a route with these two ASNs, similar to draft-ietf-idr-as0, 
section 2 "Behavior".

While I'm not convinced this is absolutely necessary, we should strongly 
consider it.  This has the advantage of clearly making any use of these 
two ASNs an actual protocol error.  As drafted, what implementations 
should do when these two ASNs are seen is ambiguous. I'm afraid some 
implementations will treat it as an error and others will not, minimally 
leading interesting operational situations, and worst case leading to 
outright incompatibilities.

On the other hand, treating it only as an operational issue keeps the 
status quo, and should not require any changes in the BGP protocol. 
But, if not explicitly disallowed, it should be clear that all 
implementations must at least provide an option to allow the use of 
these two ASNs, though.

Does anyone know if any implementations disallow the use of one or both 
of these ASNs currently or maybe planed as part of implementing 
draft-ietf-idr-as0?  Either as the Local ASN, a Neighbor ASN, or within 
the AS_PATH (or AS4_PATH as appropriate)?

Also, someone with a better understanding of RPKI should consider if 
there are RPKI issues that should be discussed for these two ASNs, I 
don't think so, but I'm not an expert on RPKI.

Thanks for kicking off the discussion with the draft.

-- 
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