Re: BGP prefix filter list

["Radu-Adrian Feurdean" <nanog () radu-adrian feurdean net>]

On Wed, May 15, 2019, at 13:44, Baldur Norddahl wrote:
> Or maybe we have a list of worst offenders? I am looking for ASN that 
> announces a lot of unnecessary /24 prefixes and which happens to be far 
> away from us? I would filter those to something like /20 and then just 
> have a default route to catch all.

Hi,

You can start here : http://www.cidr-report.org/as2.0/#Gains
You will have to do some manual work in order to identify how to optimally filter, but you may save some space.

But the more important questions are:
 - how long will it last after one round of clean-up ?
 - can't you afford to use default route ?

You can use tools like AS-Stats (or the more expensive and much more powerful alternatives) if your hardware allows it, 
in order to get the ASes that you have close to no traffic towards and leave those via default.

Or, if you can afford a dedicated internet border router, there are models that start getting to decent pricing level 
on refurbished market (a thought to ASR9001 that should be pretty cheap these days).