BGP01 An Examination of the Internets BGP Table Behaviour in 2001 Geoff Huston Telstra

The Predictions Worst Case Continued Exponential Growth 150,000 entries by January 2002 Best Case Elimination of all extraneous routing entries 75,000 entries by January 2002 BGP Table Size Date

What Happened BGP Table Size Date

BGP in 2001 Growth in Internet table size contained at roughly 105,000 entries through the year Is this a stable state? For how long? Will exponential growth resume? When?

Why? Did the Internet stop growing in size? Or are we doing a better job at managing the impacts in the routing space? Or is there some other factor at work?

Route Views View Wide variation between largest and smallest AS (27%) Main Cluster of ASs

2001 – Main Cluster Behaviour

2001 – 5 Phases January – June Continued growth in number of prefixes Mid June 3 week decline in number of entries Late August 2 week decline Late November 1 week sharp decline December Resumption of growth

Has the Internet Stopped Growing in 2001? A number of other metrics do not show the same pattern as the number of BGP table entries: Total routed address space Number of ASs Number of root prefixes in the BGP table

Internet Size: Routed Address Space

Address Space Total routed address space grew by an annual rate of some 8% Steady growth in total routed address space, modulo /8 advertisement changes Interestingly, not all ASs reach all routed address space Some balkanization is evident Not clear whether this is a result of aggressive prefix length filtering or deliberate outcomes from routing policy settings