North American Network Operators Group

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prefixes not registered in the IRR/GRR

  • From: Curtis Villamizar
  • Date: Thu May 15 00:17:36 1997

There have been a few recent incidents of incorrect routing
information propagated by major providers that have caused substantial
outages.  An example, though by no means the only example, is the
recent AS7007 announcements trig-erred by a routing software bug.  In
the AS7007 case, some providers had filters in place within 15-20
minutes while others never put filters in place and the upstream
provider took over 2 1/2 hours to block the announcements at the
source.  We've seen similar slow response in other incidents.

The AS7007 was easy to detect and isolate because very many
destinations where impacted.  Other incidents have occurred that
impacted a lesser number of prefixes.  This type of outage is very
hard for a provider to detect.

In order to insure that these routing anomalies can no longer impact
connectivity within ANS, we will begin filtering routing information
based on registered route objects in the IRR/GRR, that is the ANS,
CANET, MCI, RIPE, and RADB databases.  If you are unfamiliar with the
IRR/GRR, documentation is available at:

  http://www.ra.net/RADB.tools.docs/.docs.html

Brief instructions on registering objects are provided at:

    http://www.ra.net/RADB.tools.docs/register.html

During April ANS took routing dumps, analyzed ANS routing policy, and
identified 2,829 announced prefixes that were not registered and not
covered by an aggregate (reachable anyway).  During early April,
emphasis was placed on verifying ANS routing policy files.  From April
25 to April 29 notifications were sent to 312 origin AS, covering
2,108 of the unregistered prefixes.  Notification could not be sent to
151 origin AS covering 721 prefixes due to lack of contact information
for the origin AS.

Quite a number of the origin AS contacted registered the missing
prefixes.  Others have not responded and of course those who were not
contacted have not corrected problems.  We'd like to thank the many
people who promptly made corrections.

The number of unregistered prefixes has been reduced by almost 1/3.
There still remain 2,096 prefixes from 333 origin AS that are not
registered.  We've put together a web page describing the methodology
and listing the remaining unregistered prefixes.  The URL is:

  http://engr.ans.net/route-dumps/

It also interesting to note that 8,562 unregistered prefixes were
excluded from these reports because they were overlapped by
aggregates.  The vast majority of these were /24 prefixes.  This may
indicate that 8,562 (or more) prefixes need not be included in global
routing but are leaking from their aggregates.

Curtis
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