Check your AS: Renesys Blackout Report Released

Mike Tancsa mike at
Mon Nov 24 20:13:05 UTC 2003

On page 9, table 1 you list Allstream as being "was Bell Canada."  They 
were the network formerly known as AT&T Canada.


At 02:16 PM 24/11/2003, todd at wrote:

>Hot off the presses, from the people who brought you the excellent (and
>fun!) reports on the effects of worms on routing instabilities, how the
>Internet fared on Sept 11, 2001, and other fine topics of interest to the
>operator community, comes a new report:
>"Impact of the 2003 Blackouts on Internet Communications"
>available now at:
><a href="">here</a>
>It is an attempt to do a thorough, retrospective analysis of the impact of
>the power outages from a purely routing perspective.  We tried to be quite
>rigorous in our methodology and careful in our inferences.  However, we
>came to what may be an unpopular conclusion:  the Internet fared worse
>than others have previously reported.  The main difference in our
>conclusions lies in different measurement strategies (core to core layer
>3-4 monitoring versus global BGP routing monitoring).  Read the paper for
>more information.
>We also hoped to produce a definitive analysis of the network (routing,
>BGP) impact of the power outages so that others can compare future events.
>We're particularly interested in feedback from operators with assets in
>the affected regions of the US, Canada and Italy (see Appendix B for a
>good comparison of the Sept 28 Italy Blackout with the Aug 14 US
>A few specific ASes are mentioned in the report. We would love to hear
>feedback from those ASes or others who were affected to learn more about
>the backstory behind the outage.  If your prefixes stayed up, why?  If
>some went down and some didn't, what caused that?  Did your upstreams and
>peers stay up?  Were local power outages at routers the primary cause of
>outages, or did other factors enter into the equation?  We saw one AS with
>nine (9!) upstream ASes lose all of it's prefixes.  Could it be that
>someone with 9 upstream adjacencies didn't have reliable power?
>These questions, plus a general discussion of Internet edge reliability
>(power and interconnectedness) seem on-topic for the list.
>Of course, we read nanog :-), so we'd love to see those stories discussed
>here in a context that would help all of us understand the causes and
>mitigation strategies better, but private mail will also be gratefully
>accepted.  If you don't ever want us to mention your name in public, be
>sure to let us know.
>Todd Underwood
>todd at

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