Both sides should be filtering advertisements. The IX may just filter by AS Path which is fairly normal by the originating AS or transiting AS should be filtering the prefixes they advertise as well/ Nathan Brookfield Chief Executive Officer Simtronic Technologies Pty Ltd http://www.simtronic.com.au On 19 Oct 2017, at 17:23, Andy Davidson <andy@nosignal.org<mailto:andy@nosignal.org>> wrote: Hi, Mike On 18/10/2017, 18:39, Mike Hammett <nanog@ics-il.net<mailto:nanog@ics-il.net>> wrote: I am looking for someone that can speak authoritatively regarding AS36040's ability to change their own prefix limits, prefix filtering, etc. My current contact is advising the IX to do the filtering for them, which is not something IXes should be doing. Unless this is in conjunction with a multilateral peering session (“route-server”), when prefix-filtering is something that the IXP very much should be doing. Andy