/25's prefixes announced into global routing table?

Mon Jun 24 08:07:01 UTC 2013

Hi,

 From public routing data we can see a total of 2,419 /25s prefixes 
announced from at least one of the monitors active in RIPE RIS and 
RouteViews.
None of the /25s are actually advertised by all these monitors i.e. the 
/25s reach some but not all the ASes which take part in these projects.
The actual distribution of how many unique routing tables sampled 
contain the /25s is the following: 
http://visibility.it.uc3m.es/len25_distro.html (out of the approx. 140 
collectors that have a "full" routing table).

The top 5 ASes that are originating the most /25s are:
AS 11427:  462 /25s
AS 4766: 273 /25s
AS 45400: 109 /25s
AS 14065: 82 /25s
AS 3549: 57 /25s

If you are interested in limited visibility prefixes, i.e., prefixes 
that are distributed to some but not all the "full" routing tables at 
the interdomain level, you can find more at 
http://visibility.it.uc3m.es/ and 
https://labs.ripe.net/Members/andra_lutu/the-bgp-visibility-scanner

Best regards,
Andra

On 06/22/2013 12:00 AM, nanog-request at nanog.org wrote:
> Date: Fri, 21 Jun 2013 13:56:02 -0600
> From: Michael McConnell<michael at winkstreaming.com>
> To: North American Network Operators Group<nanog at nanog.org>
> Subject: /25's prefixes announced into global routing table?
>
> Hello all,
>
> As the IPv4 space get smaller and smaller, does anyone think we'll see a time when /25's will be accepted for global BGP prefix announcement. The current smallest size is a /24 and generally ok for most people, but the crunch gets tighter, routers continue to have more and more ram will it always be /24 the smallest size?
>
> Cheers,
> Mike