BGP Path Filtering

Leo Bicknell bicknell at
Sat May 17 00:07:31 UTC 2003

In a message written on Fri, May 16, 2003 at 08:00:00PM -0400, Sean Donelan wrote:
> Large ISPS (more than 500 eBGP neighbors and 5000 prefixes) are going to

MFN / AboveNet qualifies as a "large ISP" by your definition, yet:

> sufficient). ANS was the only major commercial provider I knew which
> explicitly configured BGP announcement filters for every network prefix
> from every source.  According to studies, about 70% of large ISPs

We prefix-list filter all of our customers.  We have from time to
time made an exception due to route limits, or people limits, but
we still exceed 99% of our customers are fully prefix-list filtered
on all inbound announcements.  It's not that hard.

       Leo Bicknell - bicknell at - CCIE 3440
        PGP keys at
Read TMBG List - tmbg-list-request at,
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