Re: Fraction of transit ASes going down? [Re: [RAM] TIDR using the IDENTIFIERS attribute]

"Ricardo V. Oliveira" <rveloso@cs.ucla.edu> Thu, 19 April 2007 19:15 UTC

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From: "Ricardo V. Oliveira" <rveloso@cs.ucla.edu>
Subject: Re: Fraction of transit ASes going down? [Re: [RAM] TIDR using the IDENTIFIERS attribute]
Date: Thu, 19 Apr 2007 12:17:44 -0700
To: Simon Leinen <simon@limmat.switch.ch>
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Yes, our measurements also confirm Simon numbers. Roughly speaking,  
about 1/3 of ASes are transit, but they originate 2/3 of the prefixes.

--Ricardo

On Apr 19, 2007, at 8:08 AM, Simon Leinen wrote:

> JUAN-JOSE ADAN writes:
>> (1) SCALABILITY OF THE ROUTING TABLE
>> We have several thousands of autonomous systems in the
>> Internet, and we treat all of them in the same way whether
>> they are transit or non-transit AS-es. But we shouldn´t
>> forget that only 1/6 are transit AS-es. And most likely
>> this fraction is decreasing over time (any figures?).
>
> You could look at
>
> http://bgp.potaroo.net/index-bgp.html
>
> and, for one or three suitable ASes, check out the history files of
> terminal, transit-only, and mixed ASes, e.g.:
>
> http://bgp.potaroo.net/1239/bgp-as-term.txt
> http://bgp.potaroo.net/1239/bgp-transit.txt
> http://bgp.potaroo.net/1239/bgp-mixedas.txt
>
> I wrote a quick Perl script (attached) and ran it on the AS1239 files.
> The results suggest that the ratio of transit (-only and mixed) ASes
> to total has remained pretty stable over the past years (modulo a
> dot-com-bubble/burst bump :-).  According to this definition, the
> ratio is more like 29%, not the 1/6 you claim.
>
> : leinen@diotima[ram]; perl hack.pl | awk '{ print $6, $5 }' | uniq -1
> 30.85% 1998
> 31.87% 1999
> 27.96% 2000
> 28.73% 2001
> 28.15% 2002
> 27.07% 2003
> 27.84% 2004
> 28.68% 2005
> 28.50% 2006
> 29.14% 2007
>
> (uniq -1 drops all but the first measurement for a given year, so
> these are the respective ~January 1 numbers.)
>
> Maybe your definition of a transit AS differs from Geoff's?
> -- 
> Simon.
> #!/usr/local/bin/perl -w
>
> use strict;
>
> my @classes = qw(as-term transit mixedas);
>
> my %by_date = ();
>
> foreach my $class (@classes) {
>     my $file = "bgp-$class.txt";
>     open FILE, $file or die "Cannot open $file: $!";
>     while (<FILE>) {
> 	next if /^-1 \d+$/;
> 	die "Malformed line: $_" unless /^(\d+) (\d+)$/;
> 	$by_date{$1}->{$class} = $2;
>     }
>     close FILE or die "Cannot close $file: $!";
> }
> foreach my $date (sort { $a <=> $b } keys %by_date) {
>     my $by_class = $by_date{$date};
>     my $term = $by_class->{'as-term'};
>     my $transit_only = $by_class->{'transit'};
>     my $mixed = $by_class->{'mixedas'};
>     next if !defined $term or !defined $transit_only or !defined  
> $mixed;
>     print scalar localtime $date;
>     my $transit = $transit_only + $mixed;
>     printf " %5.2f%%", ($transit*100.0) / ($transit + $term);
>     print "\n";
> }
> 1;
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