[db-wg] proposal: disallow creation of new non-hierarchically named AS-SET objects

Niall O'Reilly via db-wg wrote on 23/11/2022 18:17:
> What I have in mind is AS-NIALLSPECIAL, which I populate with a list of
> AS numbers which I want to advertise to let others know that these
> are to be handled in some special way, unlike those in AS-NIALLNORMAL.
> 
> According to operational circumstances, there might be periods, even
> long ones, with nothing special going on; AS-NIALLSPECIAL would then be
> empty, but only for as long as this continued to be the case.

this ^^^ is one of the failure modes.

It would not be safe to assume that empty as-sets named in RPSL policies 
are unused. It would be less unsafe to assume that unreferenced as-sets 
are unused.  A reasonable middle ground might be - after the proposed 
new unqualified as-set block has been implemented - to check out all 
unreferenced as-sets older than a specific period of time and flag those 
for deletion.

It would also be worthwhile inspecting rpsl in other IRRDBs to see if 
there are any references.  The reason for this is that lots of people 
use tools like bgpq3 / peval / etc, and query aggregate IRRDBs, e.g. 
RADB, NTT, etc.

So if you have RPSL in another IRRDB and this references an empty as-set 
in the RIPE IRRDB, that definition may be picked up in preference to 
other as-set definitions.  I.e. by removing an as-set definition in the 
RIPE IRRDB, it could unexpectedly influence routing policies elsewhere.

These are corner cases, but they should show why some care will be 
needed to figure out whether deleting these objects is a good idea.

Nick