Theorical question about cyclic dependency in IRR filtering

Mon Nov 29 12:36:37 UTC 2021

Hello everyone,

While discussing IRR on some groups recently, I was thinking if there can
be (and if there is) cycling dependency in filtering where IRR (run by
whoever APNIC, RIPE, RADB etc) uses some upstream and accepts only routes
with existing & valid route object.

So hypothetical case (can apply to any IRR):

   1. APNIC registry source is whois.apnic.net and points to 202.12.28.136
   / 2001:dc0:1:0:4777::136. The aggregate of both these has a valid route
   object at the APNIC registry itself.

   2. Their upstreams say AS X, Y and Z have tooling in place to
   generate and push filters by checking all popular IRRs. All is well till
   this point.

   3. Say APNIC has some server/service issue for a few mins and X Y and Z
   are updating their filters at the same time. They cannot contact
   whois.apnic.net and hence miss generating filters for all APNIC IRR
   hosted prefixes.

   4. X, Y and  Z drop APNIC prefixes including those of IRR & the loop
   goes on from this point onwards.

So my question is: Can that actually happen?
If not, do X, Y and Z and possible all upstreams till default-free zone
treat these prefixes in a special manner to avoid such loop in resolution?

Thanks!

-- 
Anurag Bhatia
anuragbhatia.com
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