Trends and Comparisons in Global BGP Data

[Alan Hannan <alan () routingloop com>]

          "There are three kinds of lies; lies, damned lies and 
        statistics"
        
                        - Benjami Disraeli
        
  Because I was curious, I merged 2, then 3 of these
  bgp graphs.  This is done using a graphics tool and is not
  at all alleged to be accurate, but it should be illustrative.
        
          http://www.routingloop.com/share/2bgps.gif
                - geoff's and tbates'
        
          http://www.routingloop.com/share/3bgps.gif
                - geoff's, tbates', and jhma's
        
          http://www.routingloop.com/share/overlay.gif
                - same as 3bgps.gif with 2 extrapolated trends
        
  Conclusions drawn (none of them revelatory):

        Certainly the data is dissimilar, w/ geoff's generally
        higher, undoubtedly due to the reasoning below:

> So whats going on? Inside AS1221 there is a fair number of local routes 
> (about 22,000 of them). Over the past three months AS1221 been removing 
> noise components from the external view of AS1221 (such as removing 
> asymmetric satellite services using BGP routing), and the view on these web 
> ....

        The data from different sources is quite different.  My experiences
        at a large ISP subsidiary of a large telco, upon considering
        merging w/ another large telco, caused me to do tremendous
        analysis of BGP information, such as comparing 'size' in
        several metrices, such as routes, traffic, address_space, etc..

        What I found (in this past life) was that correlating the data from 
        different sources was particulary difficult, if not impossible, 
        and that most all views into the global routing table were 
        indeed different, as Geoff states below:

> My personal take on a bottom line: every view of the BGP table is relative, 
> and changing local circumstances as well as changing global circumstances 
> generate changes in the local perspective of the BGP table. Its sometimes a 

        It does seem that we've seen a bit of a slow down in routing table
        growth.  Someone with more time should take a look at breaking down the 
        implied curves over given periods.  It sure looks like we were on a 
        slow exponential curve from ~1998 to 3Q2000.  3Q2000->Now looks like
        more of a linear growth.

        I suspect if one asked these 3 folks for the tabular data, a wiz with
        something like mathematica could do some really nifty analysis.

  -alan

  legend --     cyan = ~jhma's work
                red  = geoff's work
                grey = tbates' work
                purple = extrapolated trends