I'm looking for feedback on a filtering proposal. I propose that, on the route server, by default, we filter incoming routes to block anything matching: _(174|209|286|701|1239|1299|2828|2914|3257|3320|3356|3549|5511|6453|6461|6762|6939|7018|12956)_ We can, of course, create exceptions if necessary. One obvious one is that HE's connection would need their own AS (6939) removed from the block list. This particular list is from here, with 6939 added by me: https://www.nanog.org/sites/default/files/Snijders_Everyday_Practical_Bgp.pd... I've been using something similar in my own network for years because of a badly-behaved peer who I have been unable to set straight. They don't connect to MICE, though. This problem can and does occur at MICE. In fact, it's occurring right now. I've just emailed the relevant network. I suspect this happens because some networks filter their outgoing announcements using fixed prefix lists, not communities based on where they heard the route from. As a result, if their link to a customer goes down (temporarily or permanently), they start leaking transit routes for their customer AS. -- Richard