On 1/Aug/20 20:14, Hank Nussbacher wrote:
> AS level filtering is easy. IP prefix level filtering is hard. > Especially when you are in the top 200: > > https://asrank.caida.org/ > Doesn't immediately make sense to me why prefix filtering is hard. > > That being said, and due to these BGP "polluters" constantly doing the > same thing, wouldn't an easy fix be to use the max-prefix/prefix-limit > option: > > https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/25160-bgp-maximum-prefix.html > > https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/prefix-limit-edit-protocols-bgp.html > > > For every BGP peer, the ISP determines what the current max-prefix > currently is. Then add in 2% and set the max-prefix. > > An errant BGP polluter would then only have limited damage to the > Internet routing table. > > Not the greatest solution, but easy to implement via a one line change > on every BGP peer. > It's about combining multiple solutions to ensure several catch-points. AS_PATH filtering, prefix filtering and max-prefix. > > Smaller ISPs can easily do it on their 10 BGP peers so as to limit > damage as to what they will hear from their neighbors. > All ISP's should do this. All ISP's can. Mark.
