BGP prefix filter list
alejandroacostaalamo at gmail.com
Sat May 18 15:35:39 UTC 2019
As a comment, after receiving several complains and after looking
many cases, we evaluated what is better, to cut the table size filtering
"big" network or "small" networks. Of course this is a difficult
scenario and I guess there are mix thinking about this, however, we
concluded that the people (networks) that is less affected are those who
learn small network prefixes (such as /24, /23, /22, /21 in the v4 world).
If you learn, let's say, up to /22 (v4), and someone hijacks one /21
you will learn the legitimate prefix and the hijacked prefix. Now, the
owner of the legitimate prefix wants to defends their routes announcing
/23 or /24, of course those prefixes won't be learnt if they are filtered.
We published this some time ago (sorry, in Spanish):
That's it, my two cents.
On 5/15/19 7:43 AM, Baldur Norddahl wrote:
> This morning we apparently had a problem with our routers not handling
> the full table. So I am looking into culling the least useful prefixes
> from our tables. I can hardly be the first one to take on that kind of
> project, and I am wondering if there is a ready made prefix list or
> 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.
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