512K IPv4 Routes: The New Normal
Jim Cowie
Chief Scientist, Dyn Research
NANOG 62, Baltimore
7 October 2014
Pg. 2
Up And To The Right: IPv4 Routing Table Sizes
2009 2010 2011 2012 2013 2014…
512K
Pg. 3
Up And To The Right: IPv4 Routing Table Sizes
2009 2010 2011 2012 2013 2014…
512K
269K +30K
302K +33K
334K +32K
382K +48K
431K +48K
471K +40K
Pg. 4
Up And To The Right: IPv4 Routing Table Sizes
2009 2010 2011 2012 2013 2014…
512K
269K +30K
302K +33K
334K +32K
382K +48K
431K +48K
471K +40K
519K? +48K?
2015?
Pg. 5
“512K day” …. November 2014 (predicted) Let’s Take a Closer Look
Up And To The Right: IPv4 Routing Table Sizes
2009 2010 2011 2012 2013 2014…
Pg. 6
“Consensus” is Broadening
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
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….
“512K Day” Panic: 12 August 2014 (7:49:30 UTC)
Pg. 8
One-second BGP announce/withdraw rates (logscale)
06h00-09h00 UTC 12 August 2014
• Advertisement rate peaks first • Withdrawal rate briefly rivals advertisement rate
Pg. 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• Aggregates withdrawn, table reverts to safely less than 512K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. 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.
Rate climbs 60x in 10m
Pg. 11
Affected Prefixes, By Country
It’s not your circulatory system
2479
4494
1014
571
492 389
1084
860
727
398
595 Relatively significant impacts in Iran, Thailand, Indonesia, Argentina, Russia
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.
Pg. 13
Affected routers in critical places
Bayan (PH) loses its Pacnet transit.. twice
Pg. 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. 15
Thank you! Jim Cowie @jimcowie
Dyn Research http://research.dyn.com
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