Ok, I realized I haven't done one of these since 2001, so it's time for an updated list of /24 polluters. With /24s accounting for over 50% (more than 71k) of the announcements on the Internet, it seems reasonable to try and take a look at why there are so many.
One of the patterns which quickly becomes evident is the announcing of "almost all" of a larger block, but with enough gaps that traditional scripts which look for CIDR aggregation can miss it. For example, someone who owns a /16 and announces it as 250 /24s might not show up in other CIDR aggregation scripts because of the missing 5 /24s, or if 1 of the /24s has a different AS Path. So, solely for the purpose of looking for this pattern, I have written a script which counts the number of /24s announced within a /16 (an admittedly arbitrary range, but one which happens to work) with a consistant AS Path, and sorts by the highest count. This of course doesn't mean for certain that the netblock listed doesn't have a good reason for their deaggregation, but odds are they don't or could otherwise take steps to limit announcement to the general internet (for example a cable modem provider with 250 individual routes /24s but only a single upstream provider, who could announce a /16 globally and use no-export on the more specifics). This is done from the point of view of a Global Crossing (AS3549) transit feed, so things may look slightly different fromy our corner of the Internet. You have been warned. A summary of the top 250 netblocks by count: http://www.e-gerbil.net/ras/projects/ipaddr/24summary Detailed list of the netblocks and AS Path by count: http://www.e-gerbil.net/ras/projects/ipaddr/24dump A sorted list of the origin ASs contributing the /24s in the above lists: http://www.e-gerbil.net/ras/projects/ipaddr/24asn If you are on the list or know someone who is, please encourage them to take steps to clean up their act. You may now return to your regularly scheduled complaining about Verisign. -- Richard A Steenbergen <[EMAIL PROTECTED]> http://www.e-gerbil.net/ras GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)
