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512K IPv4 Routes: The New Normal

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Dyn's Chief Scientist, Jim Cowie, presents "512K IPv4 Routes: The New Normal" at NANOG 62. 512K relates to the discovery by multiple Internet routers that there is a default software limit of 512K IPv4 BGP routing table entries. Hitting this limit (which actually ranges from 512,000 to 524,288), has caused outages at various data centers.

Jim Cowie looks into when 512K day will happen (if it hasn't already!).

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512K IPv4 Routes: The New Normal

  1. 1. 512K IPv4 Routes: The New Normal Jim Cowie Chief Scientist, Dyn Research NANOG 62, Baltimore 7 October 2014
  2. 2. Up And To The Right: IPv4 Routing Table Sizes 512K 2009 2010 2011 2012 2013 2014… Pg. 2
  3. 3. Up And To The Right: IPv4 Routing Table Sizes 512K 269K +30K 2009 2010 2011 2012 2013 2014… Pg. 3 302K +33K 334K +32K 382K +48K 431K +48K 471K +40K
  4. 4. Up And To The Right: IPv4 Routing Table Sizes 512K 269K +30K 2009 2010 2011 2012 2013 2014… Pg. 4 302K +33K 334K +32K 382K +48K 431K +48K 471K +40K 519K? +48K? 2015?
  5. 5. Up And To The Right: IPv4 Routing Table Sizes “512K day” …. November 2014 (predicted) Let’s Take a Closer Look 2009 2010 2011 2012 2013 2014… Pg. 5
  6. 6. “Consensus” is Broadening Pg. 6 2013 2014 Today’s consensus estimate: 507K (October 6th 2014) 61% of our peers believe it’s higher than consensus 23% believe it’s higher than 512K already 512K Today: 507K
  7. 7. “512K Day” Panic: 12 August 2014 (7:49:30 UTC) Pg. 7 2013 2014 512K Today: 507K Invisible at 1hr resolution. This was a “normal intraday fluctuation” …Except that we’re so close to 512K. Global table pushed across the line….
  8. 8. One-second BGP announce/withdraw rates (logscale) 06h00-09h00 UTC 12 August 2014 Pg. 8 • Advertisement rate peaks first • Withdrawal rate briefly rivals advertisement rate
  9. 9. Affected prefixes may represent equipment suffering from TCAM exhaustion • Consensus routing table size was roughly 500,000 that morning • VZ (AS701) deaggregated almost 30,000 /24s at 7:48:38 UTC • Consensus routing table size hits 528,000 for 10 minutes • 528K > 512K; All hell breaks loose • Aggregates withdrawn, table reverts to safely less than 512K Pg. 9
  10. 10. One-second BGP withdrawal rates, logscale Most of the withdrawals in the hour are AS701 deaggregates… But 24,280 other prefixes are affected as well. Pg. 10 Rate climbs 60x in 10m
  11. 11. Affected Prefixes, By Country Pg. 11 2479 It’s not your circulatory system 1014 4494 571 492 389 1084 860 727 398 595 Relatively significant impacts in Iran, Thailand, Indonesia, Argentina, Russia
  12. 12. Pg. 12 Affected routers in critical places Russian provider Vimpelcom’s AS21332 suffers some significant impairment during the event, as seen through the lens of traceroute completion failure.
  13. 13. Pg. 13 Affected routers in critical places Bayan (PH) loses its Pacnet transit.. twice
  14. 14. Conclusions • Affected countries/networks are likely to suffer again as consensus table reaches 512K organically, “for real” • We project that this will begin occuring broadly later this month, with consensus 512K emerging by mid-November • Hopefully this brief event in August was enough to encourage people to upgrade and/or reallocate TCAM appropriately….. Pg. 14
  15. 15. Pg. 15 Thank you! Jim Cowie @jimcowie Dyn Research http://research.dyn.com

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